This is a fantastic story, and very well recounted.
> presumably because a simultaneous engine failure had been too ridiculous for Boeing engineers to contemplate
This is hard to grasp, esp. given the presence of a RAT. You're giving engineering time to add a device specifically made to handle loss of all engines, but don't spend the time to write the corresponding procedure?
> ...had determined the fuel weight by multiplying the the number of dripsticked liters by 1.77, as indicated by the documentation. However, unbeknownst to the pilots and the fuel crew, this multiplier provided the weight in imperial pounds; the new, all-metric 767 was based on kilograms, and required a multiplier of 0.8
Darn, how many of these incidents will we require until we finally get rid of the metric system once and for all!
> The internal investigation into the incident laid the blame partially upon Captain Bob Pearson and First Officer Maurice Quintal, who should have observed the Minimum Equipment List (MEL) and grounded the aircraft since it lacked functioning fuel gauges
This is an interesting take - and as the pilot of the plan it certainly should rest on you that you're responsible for all to be in working conditions before you leave. However combining that it was apparently a frequent failure, with the corporate culture that's outlined, it's a good cautionary tail about resisting the pressure when something's wrong but "everybody's doing it anyways".
Converting to metric for fuel seems reasonable but measuring fuel in weight (mass) and volume would still lead to errors using only meteric.
Distance and speeds use a mix of feet, statute miles, nautical miles, meters and kilometers depending on the context and country. Eliminating the difference would mean new approved flight manuals for each airplane, and quite expensive changes to flight instruments as well.
There’s a really good fit with feet for altitude in the U.S. that just works well. 1000’ of separation for opposite direction traffic, and 500’ separation between flight rules in the same direction. Directly converting to meters breaks all the simple math involved. Whereas if we keep the math simple, it alters airspace density and capacity.
Anyway, there’s no significant desire or effort to drop any of these units.
> This is hard to grasp, esp. given the presence of a RAT. You're giving engineering time to add a device specifically made to handle loss of all engines, but don't spend the time to write the corresponding procedure?
I imagine the RAT's primary purpose is to provide the power needed to restart an engine if all engines had stopped.
No, it provides power to power flight control systems, linked hydraulics and e.g. some flight instruments. You can't generate the power needed to re-start an engine from a RAT.
At some point, this isn't sufficient, and pilots need to start the auxiliary power unit (APU) and go through the full restart procedure as though on the ground.
But this is a moot point, given there was no fuel left...
Makes one wonder. Fuel is measurable, not only via fuel sensors, but as inertia expected vs inertia actual by laser gyro (https://en.wikipedia.org/wiki/Ring_laser_gyroscope).
There must have been some pretty deviant values on that screen. Unless the system just "calibrated" those deviances away..
> Darn, how many of these incidents will we require until we finally get rid of the metric system once and for all!
Are you serious?
There are 3 countries in the world not using the metric system. The non-metric system is difficult to use because it's using 12 based units with a 10 based numbering system.
Sure switching over is going to be painful but that's true either way, and there are quite a few examples of people switching to the metric system but none, as far as I know, the other way around.
On jul-25 at 11am pdt, charles_f was standing out to comment on an interesting aviation story. Seeing in passing a reference to issues regarding imperial and metric systems confusion, and given the popularity of this kind of debates on the internet, they decided to set course on a "joke".
The joke was thusly constructed: the metric system is commonly used across the world and much more sensical than outdated imperial system, and people commonly announce their discontent for the latter and ask to discontinue its use. Therefore commenting using the opposite point of view as if it were an evidence, and in a serious tone, had a chance to trigger surprise and interrogation in the reader's mind, quickly resolved by the idea that the author wasn't being serious and making fun of this debate, and triggering a chuckle. This type of jokes is commonly referenced as "sarcasm" in the professional jokers world.
But before the joke took flight, the joke funniness sensor wasn't working, as well as the joke and sarcasm announcement systems. The author sent Robert, their left moustachioed fat finger, to dip in the joky tank, and check if it was fun. Robert answered "yo bro yain't starting to finish all your jokes by 'just kidding' like a brainless soccer dad".
Based on this manual reading the author was reinforced in their certainty that the joke would work and maybe make someone else's life a little brighter for a half second (500 time thaus, for those using imperial), and decided to take off.
We all know the result. The joke worked, as some people understood it, but not all detected that it was one.
The author would like to apologize for, and retract the "<joke/>" that they added as a comment to their original comment, since adding a revelation that a joke is, indeed, a joke, undercuts the element of doubt and surprise necessary to maximize its effect and duration. The same goes for lengthy, rational discussions about said joke and should be avoided. (It turns out that this particular type of joke can be delivered in their lengthier form, which get ruined if its actual, underlying agenda is revealed in plain text). As such the author would like to also immediately retract this statement and apologize for it.
I think the GP might be yanking our chains a little bit.
Also you kind of have to include the UK in the list of countries that use imperial measures. We're mostly metric but the roads are in miles/yards and if you tried to take pints (which are larger than American pints at 568ml) out of British pubs in favour of the smaller half-litre it would make the party that did it instantly unelectable. People are nearly always measured in feet and sometimes weighed in stone (14 lb) too. I'm a little surprised we don't measure fuel efficiency in miles to the litre because that would be pretty typical of the British approach to measuring things.
I actually don't think it's a bad thing, a bit of mental maths never hurt anyone and it underlines the fact that units of measurement aren't handed down on a stone tablet as a fact of nature.
Who really cares what names the glasses in bars have? Canada, Australia and New Zealand all use the metric system, and all sell pints of beer in their pubs. Australia and Canada also sell schooners of beer, which come in 425ml and 946ml sizes respectively (where a schooner is 103ml in the UK).
No matter what system a country uses, there’s nothing stopping a bar from selling 568ml portions of beer, and giving you one of those when you order a pint.
> there’s nothing stopping a bar from selling 568ml portions of beer
The law (via regulations) stipulates what sizes can be sold. As an example, this[1] from 2011:
> The centuries-old cry of "fancy a pint?" may soon become "fancy a schooner?" under plans to relax the strict rules dictating drink sizes.
> Current regulations mean draught beer must be sold in pints (equivalent to 568ml), halves (284ml) or the little-known "thirds", and wine in measures of 250ml, 175ml or 125ml
Whatever the regulations about portion sizes are, they’re independent from the measurement units used. The government is allowed to regulate portion sizes of 568ml, 284ml and 189ml.
Also, is it really illegal to serve a 150ml glass of wine in the UK? That’s insane… A 750ml bottle of wine is supposed to have 5 glasses in it, not 4.28
> if you tried to take pints (which are larger than American pints at 568ml) out of British pubs in favour of the smaller half-litre it would make the party that did it instantly unelectable.
Definitely something only a government with the ability to essentially erase history would able to pull off.
>>> if you tried to take pints (which are larger than American pints at 568ml) out of British pubs in favour of the smaller half-litre
FYI here in metric-land (well, Italy) we normally have glass of beer in the size of regular (600ml) and small (400ml), and half litre is usually used only for weissbier
> There are 3 countries in the world not using the metric system.
The US uses metric for many, many things. Frequently side-by-side with imperial equivalents. AFAIK it's also the official position of the USG that metric is prefered.
> The non-metric system is difficult to use because it's using 12 based units with a 10 based numbering system.
OTOH, 12 divides evenly by both 4 and 3, which are common divisions.
> > The non-metric system is difficult to use because it's using 12 based units with a 10 based numbering system.
> OTOH, 12 divides evenly by both 4 and 3, which are common divisions.
If we could go back to the dawn of civilization and choose a base 12 number system that would be nice, but a bit late to change now. (IIRC ancient Sumerians used a base 60 number system, but that eventually fell by the wayside).
That being said, nothing prevents one from choosing dimensions that are a multiple of 12mm e.g. when woodworking.
It's mildly worse than that, because the US uses metric side-by-side with US customary units, which at least for volume use the same unit names as Imperial but are smaller.
(Does the US use Imperial as well? My most common experience with US vs imperial measure is in pints of beer, although Canada has caught on to the 16 oz pint, and don't even start me on 12 oz "pints".)
The US does not use Imperial measurements that I know of, which can be confusing to Americans if UK mpgs are interpreted as equivalent to US values.
But there's more than one kind of ounce in the US. Fluid ounces are volume whereas dry ounces are weight/mass. From memory - and I memorized this from cooking - 8 fluid ounces (one cup or a half pint) is 8.337 dry ounces (assuming the approximate density of water).
Then there's metric horsepower vs. other types. It's clearly so much more natural for a horsepower to have a German name (pferdestärke!) and mean 735.5 watts instead of 745.7 watts (numbers copied and pasted, not checked).
> From memory - and I memorized this from cooking - 8 fluid ounces (one cup or a half pint) is 8.337 dry ounces (assuming the approximate density of water).
Why memorise this to such precision if you're already approximating away the density? The job is already done for you, 8 dry ounces is approximately 8 fluid ounces, whether its water, milk, oil, or orange juice. If you need to measure liquid mercury, you're not working in the kitchen; if you need greater precision, you need to measure mass or volume directly as appropriate.
Because that was the precision used by the particular author I got it from. It's not that the fourth s.f. really matters. I think the 7 actually helps my memory by making the number distinctive and not just 8 1/3.
It's like remembering that body temperature is 98.6 F. It's obviously false precision and it's not even an accurate average, but it's the way it's traditionally recalled - plus it works out to exactly 37 C.
>8 dry ounces is approximately 8 fluid ounces
I did write "cooking" originally and it is a valid point that when cooking as opposed to baking usually a little more or less liquid is immaterial.
But I meant to include baking and, say, mixing drinks.
A 4-5% difference isn't always important, but it's often noticeable. I've been using a digital kitchen scale for >20 years, and I just find volumetric measuring cups annoying compared to going by weight. I don't want to go back and forth filling a container and checking it on a level surface, to eyeball a meniscus, to wait for every drop of a viscous liquid to fall, or to sift flour.
I don't cook or bake with liquid mercury, but I use sugar, which is ~7 ounces per cup, and flour, which is (according to me) 4.25 to 4.5 ounces per cup. That's considerably different from 8 = 8.
If you are in engineering or physics in the US, you use metric.
There are some beautiful conversions too: 1 m^3 of water is 1000 kg or 1 metric ton. It is also 1000 liters of water.
Wait until you run into the Imperial system's slug, a derived unit of mass, or the blob, the inch-based unit of mass in the Imperial system. 1 blob is 12 slugs.
The metric system is just logical and cleaner than the Imperial system. No crazy conversions e.g. 1 ft = 12 inches, or 1 ft / 5 = (1 ft * 12 inches/ft \ 5 = 2.4 inches = 2 inches and 0.4 inches is almost 25/64 or 13/32nds!!)
1m = 1000mm or 100cm and 1m / 5 = 200mm or 20 cm.
1m / 3 = 0.3 (repeating decimal) m or 333.3 (repeating decimal) mm. No fractions needed.
I can't tell you how many people struggle to read a tape measure down to a 1/16 or 1/32 or in machining to 1/64 and not really grasp it. Uncertainty in measurement is a recipe for disaster in science and engineering.
> OTOH, 12 divides evenly by both 4 and 3, which are common divisions.
Interestingly, I don't hear pro-US-unit people apply this to money. The UK used to use money not based on 10, but changed during the 1900s. So it's not without precedence.
If 12-based is so great, I'm looking forward to the US listing prices as "10 dodecadollars, three dollars, and 3 dodecacents".
But how else would these freckled ninnies know when sarcasm is implied, if not spelled out explicitly for them in the form of some putrid postscript marking?
I've heard that some countries half converted and it's been a disaster for them. They're using grams and meters but are still clinging to on the old base-12 time-keeping system. I hope the US doesn't stumble down the same path.
There are procedures, but they are to general and to emergency-manifold to help. Its basically aviate, communicate, crew-resource management applies kind of rules.
In this case, discover how the plane flies, glide it towards a landable location, while communicating your intentions and location. Do not get panicy, do not get burdened with to many things (the pilot monitoring not telling about people on the runway counts as such).
It makes no sense to capture all the permutations of that.
Just get it down somewhat safe.
They forward-slipped a Boeing 767 to bleed off the remaining altitude! A forward slip is a cross-controlled maneuver that feels unnerving and wrong enough in a Cessna 172, let alone a Boeing 767. And they did it with minimal hydraulic assistance as well...
I believe TACA 110 did the same thing to lose energy on an unpowered approach. It's not normally done because the turbulence induced can cause one of the engines to flame out. This is not a problem when the engines are already not operating, of course.
For the non-pilots here, roughly what is a forward-slip? I understand a little bit about flying, but not enough to grok the explanations/diagrams.
Is it a high-altitude, low-power approach to the runway, where full flaps are used to bleed off more altitude and speed? How is that different from a regular approach?
The ideal approach to landing is what's called a "stabilized approach", in which the aircraft descends to the runway at a constant 3 degree angle and constant descent rate. If the pilot finds themselves with too much altitude too close to the runway, in other words above that glide path, they need to more aggressively descend to meet the glidepath.
One way to aggressively descend would involve just pointing the nose down, but this has the effect of increasing speed (trading altitude for airspeed). You need a way to descend more quickly without increasing speed. Generally, this is done by adding more flaps (increasing drag), but in the case of the Gimli Glider, their hydraulic systems were down, so they could not add more flaps.
A forward slip is a maneuver in which you roll the aircraft such that the top of the wing and side of the fuselage are exposed to the oncoming air (relative wind), and you use the rudder in the opposite direction to keep the aircraft flying straight (with respect to the ground track). When properly executed, the rudder and aileron cancel each other out so you keep flying straight across the ground, but the nose of your airplane is not aligned with the direction of travel, and the top and side of your airplane is exposed to the oncoming wind, significantly increasing drag, and thus descent rate.
A forward slip is a maneuver in which you roll the aircraft such that the top of the wing and side of the fuselage are exposed to the oncoming air (relative wind), and you use the rudder in the opposite direction to keep the aircraft flying straight (with respect to the ground track). When properly executed, the rudder and aileron cancel each other out so you keep flying straight across the ground, but the nose of your airplane is not aligned with the direction of travel, and the top and side of your airplane is exposed to the oncoming wind, significantly increasing drag, and thus descent rate.
You Tokyo Drift the plane, exposing more of the side of the plane to the forward motion of the plane to increase the drag by using the side of the plane as a air-brake.
Instead of the most areodynamic way of flying straight, and the worst aerodynamic way of flying completely sideways, you power-slide the plane so that it's not dead-straight and the extra wind-resistance slows you down.
One of the pilots had sail-plane experience from riding a one-man ice-boat with a sail attached over an icy lake - which is where he learned the maneuver. You can slow your speed by the same trick, it's just not usually done with an airliner.
> One of the pilots had sail-plane experience from riding a one-man ice-boat with a sail attached over an icy lake - which is where he learned the maneuver
This is correct, but I want to note that every Private Pilot (in the US at least) learns this maneuver, and it is required to be demonstrated to an examiner on the Private Pilot practical checkride.
While true, your comment is focusing on what I think is the second most important aerodynamic force in a slip, which is the wind resistance if the side of the plane.
By far the most interesting thing going on is that you’ve destroyed lift. The ailerons are acting as spoilers essentially so the plane starts to want to drop out of the sky.
I’m a pilot, and the sensation of a slip is definitely not that you’re rapidly losing forward groundspeed, it’s that you’re suddenly not gliding, and instead kind of dropping out of the sky.
It feels different in different planes - I always felt the Cessnas were glued to the sky no matter how much I slipped, but the pipers would drop like a rock if I needed them to.
> Instead of the most areodynamic way of flying straight, and the worst aerodynamic way of flying completely sideways, you power-slide the plane so that it's not dead-straight and the extra wind-resistance slows you down.
That is actually not completely true. You are mainly increasing drag to lose altitude quickly WITHOUT gaining additional airspeed. Remember, backside of the power curve, pitch for speed, power for altitude. You could push the nose down to give up altitude in a power out, flaps out configuration, but you might overspeed your flaps by gaining airspeed. That is why you have the Tokyo drift.
I used to fly a couple times/week for work and one I time I could see our runway out of my passenger window as we were landing, and we were heading directly for it. I just thought it was very windy, but I'm now learning that maybe Vin Diesel was at the helm that day. Very good explanation, thank you.
Uh..yes. But that's not the goal of a slip. You're describing the first flight lesson for every pilot. And it's true, but not relevant for the discussion of a slip. The goal of a slip is to quickly lose altitude without changing airspeed. If you need to quickly slow down, chop and drop and pitch up.
It is where you fly the aircraft sideways through the air.
It is a way of dealing with the situation where the wind is not coming straight down the runway while landing a light power aircraft. You point the aircraft straight down the runway and add in enough bank to overcome the drift to the side. You use the rudders to prevent the aircraft from turning due to the bank.
Pearson was performing the forward-slip in the less common context of gliding. While flying gliders the problem is that they produce a glide angle that is much too shallow to ever be able to control exactly where you are going to land. Normally you use spoilers (AKA dive brakes) to control glide angle but the spoilers might fail or you might need a steeper approach angle than the spoilers can provide. So you fly sideways to force the side of the glider through the air and produce more drag. You still need to take into account any crosswind while simultaneously adjusting the glide angle while staying lined up with the runway. It's a bit tricky and it takes some practice to maintain the skill. That's why I get to demonstrate a forward-slip as part of my yearly glider check flights.
Pearson did this in an airliner with constantly changing control forces and completely nailed it on his first try. He touched down something like 100 feet past the threshold which is exactly what you want to do in a case where you don't have a lot of braking available. This was one of those times where you wanted the guy that lives aviation and not the nine to fiver.
My only quibble with that animation was that it didn't show the state of the control surfaces, such as the rudder not appearing to have been moved when it was clearly at or near max during the real incident.
I think it's fair to describe a forward slip as a maneuver that puts the airplane sideways to use the drag of the fuselage, which is now partially side-on to the airstream, to bleed off speed (energy, really). It's used in situations where you need to bleed altitude quickly without gaining airspeed, which would typically be the outcome of just pointing the nose down—you trade gravitational potential energy for kinetic energy.
I'm also not a pilot but, based on a diagram below, it looks like you roll the plane and apply full rudder in the opposite direction. The opposing roll and rudder keep the plane tracking straight but the control surfaces fighting against each other add a bunch of drag to lose airspeed.
Essentially you fly slightly sideways towards the target landing spot on the ground, which loses speed and/or altitude quicker than you otherwise would.
This is done by applying rudder and ailerons in opposite directions (e.g. full right rudder and enough left aileron to still be heading towards the intended spot).
Typically this would be a bad thing as it feels weird and is inefficient, but in this case the whole point is to be inefficient in order to lose altitude without gaining too much speed.
> Both forward and sideslips involve opposite aileron and rudder input. In a forward slip (typically used to increase drag and decrease altitude), the aircraft’s nose points away from the direction of flight, with the lowered wing facing the direction of flight. In a sideslip (typically associated with the final stage of a crosswind landing), the aircraft’s nose points in the direction of flight, regardless of which wing is lowered.
and
> To understand the difference between a forward and a sideslip, we need to understand the slip in general. A slip, at its core, is an uncoordinated turn. In other words, when the ball of the turn coordinator is not in the middle, you’re in a slip.
So in general, a slip is a situation where you're banking, but not turning, due to opposite inputs to ailerons and rudder (i.e. between stick and pedals).
As I read through all that, I thought I was coming to a decent understanding. However, finally,
> The jargon is unnecessarily confusing – you move forward during a forward and a sideslip, but you don’t move sidewards during a sideslip; you technically move sidewards during a forward slip!?
It’s use case specific. And depends on perspective.
Forward slip is mainly used to lose altitude without increasing airspeed, such as emergency descent or when too high on approach for landing.
Side slip is mainly used to maintain lateral alignment with runway centerline during a crosswind landing.
The side slip is predicated on a crosswind, properly done the two forces equal. In effect like “leaning a shoulder into the cross wind” to stay laterally and longitudinally aligned with the runway.
Does a turn require a curve in the airplane’s direction? What exactly constitutes a turn? If a plane is in a bank, there is a horizontal component of lift. But if there’s no change in direction (either heading or ground track) is it a turn?
While there is such a thing as a slipping turn, it means an (insufficient) change in direction for the bank angle. If the rate of turn is zero, it’s just a slip.
Conversely I don’t see how you get a skid without a turn.
Flying door handle first, with Déja Vu roaring in the background. (I might be exaggerating a little. Also not a pilot.) It looks like you have to use the rudder and bank slightly so that the plane is still flying "forward" but the nose points away from that direction.
An extremely simplistic way to think of a forward slip is for the pilot to have the rudder pedals hard in one direction, stick/wheel hard in the opposite direction.
Generally to turn left you bank left using ailerons. This angles the lift vector to the left and the airplane will turn that way without using the rudder, but it's not fully coordinated - the plane won't be pointing properly into the turn - it will "skid" a little, creating more drag than necesssary. To coordinate the turn, a small amount of left rudder is used to yaw the plane left just enough.
In a forward slip the goal is to descend more quickly than you otherwise could. If you just point the nose down, the airplane will gain airspeed. If you're trying to descend quickly you'll overshoot where you're aiming. What you want is a lot more drag, which allows you to point the nose down (reducing lift) without gaining airspeed. Normally flaps, spoilers or airbrakes allow you to do this (depending on the aircraft). If you don't have these, as the Gimli glider didn't, what can you do to increase drag? Well, you can use the whole fuselage as an airbrake.
To do this, you can use the rudder to yaw the plane, so it's flying a little bit sideways. Say we yaw it to the left. If the wings have dihedral (they point slightly upwards) then the right wing now has a greater angle of attack than the left wing - the right wing produces more lift and so the plane will bank left by itself without touching the ailerons. If the wings are swept back, as on large jets, yawing left will mean the right wing is longer with respect to the airflow than the left wing, and it will bank left even more. To fly pointing left, but not turn left, you cross the controls: you use the rudder to yaw left, and the ailerons to bank right. The airplane is now flying partly sideways, pointing to the left of the flight path, with the right wing lower than the left wing, but if you balance rudder against ailerons correctly, you fly in a straight line. The fuselage is partly sideways to the wind, creating a lot of drag. The airplane is skidding downwards to its right, and you need to pitch the nose down to maintain airspeed and avoid stalling.
And then you've got to be fairly well coordinated as you come out of the slip so you keep flying in the direction of the runway.
Source: I used to fly gliders. Presumably swept wings increase the amount of aileron needed, but the principle is mostly the same.
That's strange. Not saying slipping a 767 is a walk in the park, but I routinely slip Cessna landings (182s and 206s) because I just need to get down. It is a little weird, but no where near unnerving and for sure not wrong.
It’s perfectly normal in a small plane and the center of gravity doesn’t move much because the plane is small. (Technically center of force vs gravity yaddayadda)
Anything a small plane can do a big plane can (very few exceptions), so they can slip just fine, like they can do a 60° bank just fine - but it becomes VERY uncomfortable for the passengers - who now will feel they’re “outside the plane”.
> they can do a 60° bank just fine - but it becomes VERY uncomfortable for the passengers
Only if you try to maintain altitude. If you let it descend it can be a 1G maneuver and no one will be able to tell unless they look out the window (at which point they will probably freak).
Its not inherently wrong, but flying cross-controlled feels wrong to me. Probably because I don't do it very often, and I'm aware of the fact that it increases my stall-to-spin risk if I don't properly manage airspeed.
While approaching to land, you are on the backside of the power curve, so pitch for airspeed, power for altitude. You have correctly indicated about managing airspeed. But it is not as difficult as it sounds. If you were flying at the beginning of the slip, you will continue flying through the slip unless you mess with nose positioning, or pitch. TL'DR, DON'T PULL UP while you are in cross control.
Here are some suggestions. As one of the child comment stated, go fly a glider for a few hours. It will immensely help with flying "not straight". I started it for gaining better understanding of flight but ended up finishing a commercial ticket on glider as well, because I enjoyed it so much and also just for the bragging rights.
Secondly, cross control is perfectly safe till the time you pull back on the stick. That is how you get into cross control stalls, the starting configuration for a spin. When you are slipping, you should actively trim nose down, (that you should have done already, remember you are approaching to land), and maintain just a little forward pressure as you fly sideways. I would recommend, grab a competent CFI and get cross control stalls nailed. I know it is not a part of PPL, something I am very pissed about. Hell, PPL in US does not even need spin training. Bollocks, if you ask me....
I've done gliding and we didn't really do forward slips that much. Perhaps US glider brands are different but all the European (German and Czech) ones I've flown had huge spoilers/airbrakes that were more than sufficient to waste altitude quickly without increasing airspeed.
It's actually a really nice way to land, I wish powered aircraft had this.
If you have the chance (and didn't already do so), make a few flights in a glider with an FI.
I thinks it's a different kind of flying and allows you to be more confident in certain situations such as slips, slow flights and engine out landings.
The linked article is not bad but reads a bit too much like a Dan Brown novelization for me taste… “ The mustachioed Captain Pearson pulled out the trusty Boeing handbook, his fingers dashing through the pages…”
The Admiral Cloudberg article is much better, particularly in its explanation of how the plane came to be flown with blank fuel gauges. The first technician noticed an issue with the fuel gauges being blank a few flights earlier and applied a fix he happened to know: disabling one of the two channels, which restored the gauges. This was an acceptable fix - the plane was certified to fly with only one of the two channels active, as long as the lost redundancy was regained with manual checks. It was flown twice in this state (working gauges, single channel, manual backup fuel check).
When this captain handed the plane over to the captain of the incident flight, there was a misunderstanding in the conversation that led to the incoming captain believing the prior captain had been flying with blank fuel gauges and only manual fuel checks. In an unfortunate coincidence, the second technician who was checking the plane at this time disabled both channels to try and troubleshoot the issue again, but failed to return the system to the “one channel” functioning state (apparently because he was interrupted by a request to help with the manual fuel check, ironically).
The second technician’s mistake would have been noticed by the pilots, except that due to the misunderstanding, they were expecting to see blank gauges. Those were the initial conditions that allowed the “pounds, not kilograms” mistake to threaten the flight.
Definitely. What makes Admiral Cloudberg so good is the intense focus on details: both details of technical systems, and details of how humans (mis-)communicate with each other. Those details are where the reasons for failure reside, and so they are the place to focus if you’re interested in these stories from an incident analysis perspective.
With flight 143, the sheer brilliance of the flying after the fuel ran out - plus the too-neat story of “it was all caused by metric / imperial conversion” can easily distract from the real lynchpin of the whole incident, which was as you say why the plane was flown with non-functional fuel gauges when that was contrary to the Minimum Equipment List for the aircraft. Taking off with blank fuel gauges was the core safety rule that was violated: the mistake with the unit conversions was necessary to make that violation dangerous but it wasn’t really the core of the accident.
Nearly all airliner crashes are due to an unexpected confluence of multiple errors. If any one of the errors had gone right, nothing bad would have happened.
Wasn't there active attempts to hide the extent of the issue with Chernobyl which significantly worsened the damage? If so, that seems like saying there were cascading human errors in a murder-suicide. You're technically right on some level, but I wouldn't so much call that human error.
I have no direct knowledge of this, but I'm sure it happens all the time. It's just that there's a lot of redundancy in all aspects of flight operations. For example, there are two pilots. One pushes the buttons, the other crosschecks it.
If you fly Air Canada, they'll have you believe that a single light in one of the three the restrooms is a critical safety concern, and that's the reason for your 6 hour delay without compensation.
I'd almost say the two make good companion pieces. DI's is a masterclass in nonfiction storytelling, while Cloudberg's is equally adept in its detailed, high-stakes procedural drama.
It's an incredible enough event that it's worth reading both!
I, for one, quite enjoyed the novelization of it. Especially the part about the space-irony continuum. My sleeping wife did not appreciate being woken up by laughter though.
There is one part in that article that I cant understand. It says:
> ...when flight attendants opened the rear emergency exits, they found that the tail was so high in the air that the slides didn’t touch the ground. Sliding down them was less like schoolyard fun and more like jumping off the second or third floor of a building
But then it proceeds showing a photo of deployed rear exit slides, and judging by human standing there they almost touched the ground, the difference is like half that human at most. Now, while I agree that jumping from 1 meter may be too much for some people, comparing it with 3rd floor jump is totally out of place. What am I missing here?
I am guessing that the slides would swing backwards into a more vertical position if someone were to try to use it, because the bottom wasn’t touching the ground and thus preventing the swinging movement. This would then cause the slide to then be an essentially vertical drop instead.
That was a great article. It seems ridiculous to me that the pilots were punished for this given very specifically the unclear delegation of responsibility when automation was introduced. And if ignoring the MEL was a company culture issue, then it was a company culture issue, and you won't make the company safer by encouraging people not to reveal violations.
The thing that gets me in the originally posted link is that the author decided since this was Air Canada, every single person involved must end their sentences with 'eh'.
Author of the linked article here. If you're implying that I manufactured the "eh"s, you are mistaken, they were in the transcript of the cockpit voice recorder. If you are implying that I intentionally left them in for comedic value, I cannot argue with that.
Indeed, thank you for your attention to that detail. I would expect that cockpit recordings from Yanks would have plenty of sentences ending in "Huh?", as in "Ya remembered ta turn that switch off, huh?"
And to the person who said they routinely slip Cessna landings... different bird my friend ;) Remember, the slower they get the less the hydraulic assist was working. It's a wonder they were even able to straighten out.
I hope there is some kind of 'case study' that pilots study about this.
It should not be up to the pilot to ground the plane; shouldn't that be up to the airline or chief engineer?
>It should not be up to the pilot to ground the plane; shouldn't that be up to the airline or chief engineer?
Aerospace engineer here. I've worked in airworthiness and maintenance ops, though never on the 767. "Grounding an aircraft" is usually a colloquialism, but there are several people who can declare aircraft to be unserviceable and that includes both pilots and maintainers.
For the uninitiated, what happens is the maintenance organization does what's called a Maintenance Release[0] which is the legal act of transferring the aircraft out of maintenance and certifying it is in compliance with what's called the Approved Type Design. Because of the real world being what it is, there are legal ways to accept an aircraft that isn't in compliance with the approved type design and these take the form of Minimum Equipment Lists (MELs) which are basically a list of pre-approved deviations from the Type Design for which risk management has already been carried out. For example in some aircraft you can take off without life rafts, if your aircraft carries a legal operating restriction to stay within $distance of dry land.
Upon accepting an aircraft for a particular flight, the pilots do their own acceptance checks, the common term for which is "preflight".
Anyways, the long and short of it is that yes, the pilots can and should ground the plane if it's U/S. But maintenance can and should as well. In this case, the pilots were sanctioned because they contravened the MEL for the 767 which was a contributing factor to the incident.
Seriously. I had my personal sites on Dreamhost shared hosting back in the 00s and found DI when it was featured in the Dreamhost newsletter as their site of the month or whatever— I wonder if it's still hosted there?
Yes indeed, we are still on Dreamhost. With almost 20 years of hosting sites there, we get some nice discounts from their referral program--otherwise we'd probably change hosts.
"A crew of engineers from Winnipeg airport clambered into a van and headed for Gimli to assess the damage. During transit, however, their vehicle unexpectedly ran out of fuel, nearly ripping a hole in the delicate space-irony continuum."
I didn't know a space-irony continuum exists, but makes sense. ;-)
OP was on the flight with his parents and had the tickets framed. Also the Captain of the flight is now his stepdad and his dad was head of maintenance for Air Canada at the time.
> The internal investigation into the incident laid the blame partially upon Captain Bob Pearson and First Officer Maurice Quintal, who should have observed the Minimum Equipment List (MEL) and grounded the aircraft since it lacked functioning fuel gauges. Some of the responsibility was also assigned to the maintenance workers, and to “corporate deficiencies.” As a consequence Pearson was briefly demoted, and Quintal was suspended for two weeks. Nonetheless both pilots continued to work for Air Canada, and in 1985 they received the well-deserved Fédération Aéronautique Internationale Diploma for Outstanding Airmanship for their handling of the unusual landing.
Interesting. What kind of demotion did Boeing or Air Canada receive?
Air Canada changed their pilot training, changed several manuals and documents, standardizing the fuel weight units (which was already in process), changed the circuit breaker, established a flight safety organization, and changed fueling procedures.
The story does not say if any person responsible for those parts got any negative consequences, thought one can hope that the hunt for blame was short. It usually doesn't serve to improve security, and in this case there was a long list of consecutive mistakes by a large number of people that allowed for the accident to happen. Among those were also a culture of overriding the Minimum Equipment List, something which Canada had outlawed 5 years before this accident.
I was on a United flight in 2019 that had to be diverted due to tornado warnings at the destination (DC). We circled Columbus long enough that eventually the pilot announced that he was still waiting for authorization to land and that it should be soon because we only had about "20 minutes" worth of fuel left. He announced 45 minutes later that we were going to land in Pittsburgh instead, without providing an update on the fuel situation. We glided until we landed, with all lights turned off and violent winds throwing the plane around. The plan was to refuel and keep going toward DC, where tornado warnings hadn't been dismissed. There was an airline employee (not sure if he had been on the plane) at the gate aggressively telling people, some of them crying on the phone with loved ones, that they had to get back on this flight, with the same crew. He lied to me about my luggage continuing on to DC if I didn't get back on the plane (this is illegal and in fact I found my luggage at the Pittsburgh airport the next day when I went to get my flight out of there).
The only thing I found about it online is a couple of tweets from other passengers of the same flight.
That notification you got about the "20 minutes worth of fuel left" meant before they were forced to divert to the alternate.
There are numerous FAA requirements about this depending on if you are IFR/VFR, the airport, the expected weather, etc. but the bottom line is sufficient fuel to:
1) Fly to your intended destination.
2) Fly from the destination to the alternate (if required).
3) Fly for an additional 45 minutes at normal cruise speed (minimum).
What the pilot was saying was that they had 20 more minutes until they had to go to Pittsburgh. If it took 45 minutes instead of 20, it was because the computer calculated that was exactly how much more time they could hold.
There was no gliding on your flight. It may have felt that way during a descent at flight idle.
The flight may have been scary to the passengers, and people may not have wanted to get back on, but I'm sure it was quite routine to the people up front.
Source: US certified commercial pilot, Aero. Sci. degree. Certified ATC.
> That notification you got about the "20 minutes worth of fuel left" meant before they were forced to divert to the alternate.
I believe you but this is yet another reason why it was inappropriate for the pilot to mention this to passengers. Nearly everyone around me was visibly distressed as we "idled" to Pittsburgh.
> The flight may have been scary to the passengers, and people may not have wanted to get back on, but I'm sure it was quite routine to the people up front.
Maybe for the pilot/copilot but the flight attendants' facial expressions when I got off the plane did not suggest to me that this was routine.
At some point you kind of need to assume the pilots aren’t suicidal nor are they complete idiots, and it would be ridiculous for them to simply circle around aimlessly until they run out of fuel. Being motivated for survival, they are going to fly to the nearest appropriate airport well in advance of an actual emergency situation.
Further consider that other than this story—where the aircraft ran out of fuel due to a wildly unlucky confluence of technical and human failures—you have never heard of a passenger jet running out of fuel midair. Through decades of storms, hurricanes, tornadoes, and every other natural disaster imaginable, we have found a way to get planes onto the ground with fuel to spare.
The flight attendants know that the pilot is not going to intentionally let the plane run out of fuel and will land before that happens, even if means declaring an emergency and diverting to any available airfield.
Also someone on the ground crew on New Year’s Eve pulled into the engine, though they apparently disregarded multiple warnings about clearance distance from the engine even after nearly getting knocked over by exhaust. I’m not sure how that sort of thing (disregarding multiple warnings & a near miss) can be prevented:
That was a different one, in Texas more recently. I have to wonder if the person was influenced in their choice of method by the relatively recent news of another dying the same way. In the end that of things, the method, probably doesn’t matter much.
988
Dialing that, at least in the US, will get help to anyone who needs it
The engine shredded itself midflight and blew a hole in the fuselage next to her seat. The other passengers held her and prevented her from being completely sucked out but she still died from her injuries.
That flight certainly did not do any unpowered gliding. With their "20 minutes left" line, the pilot likely meant "20 minutes until we hit our reserve fuel", at which point they would be forced to declare a fuel emergency and land at whatever airport is available.
If so, the pilot would have done better to keep his mouth shut. Why the hell would someone say that to a bunch of passengers who are presumably totally untrained in aviation?
Because it makes no sense to assume that the pilots, at least one of whom presumably prefers to continue living, would just circle around to the point where the engines quit?
The pilots are in the same plane as you. They aren’t going to just let the plane run out of fuel because some person on the ground says “sorry, can’t land at this airport yet, hang out for awhile”.
If there was a real emergency they’d be putting the plane down on the nearest runway-shaped surface no matter what.
Further, I’d wager the pilot said something along the lines of “we have twenty minutes of fuel before we need to consider diverting to [alternate airport]” or something to that effect.
Absence of information is almost always way more scary (and sometimes leads to panic) than the presence of even a little of some.
Maybe pilot wanted to say what there is still enough time for them to keep waiting, but in that situation didn't though how that phrase would sound for the passengers.
I find it hard to believe this story really happened the way you are presenting it. "We glided until we landed" makes it sound like the plane ran out of fuel - did it really? It would be hard to hide such an incident. Your strong language ("lied", "illegal", "absolutely inappropriate" further down) makes me think there is more nuance to this.
Edit: "with all lights off" - turning off the lights for a landing is regular procedure, nothing unusual.
Your intuition is correct. The story as told by the parent is likely just due to a misunderstanding (or just lack of knowledge) of 1) the pilot's words over the PA and 2) standard procedures used in commercial air travel.
Especially in emergencies. Lights are turned off so passenger eyes can get used to the dim light and see the exit lights (which are not bright) better.
> turning off the lights for a landing is regular procedure, nothing unusual.
The lights were off for about an hour as we glided toward Pittsburgh.
> Your strong language
My assessment is that I was told my luggage would continue on to DC without me if I didn't board in an attempt to get the plane leaving as soon as possible after refueling. I didn't care enough to get back on, and learned the following day that they had actually removed my luggage before departure.
In situations like this, it helps to remember that there is no disjoint between you and the pilots. They are in the same exact situation as you: if the fuel runs out, they crash the same as you. They're not willfully going to put their (and your) lives in danger. They want to get home safely to their families the same as you do.
Dispatch and route planning (and the fuel that goes into the planning) is really intense and takes into account hundreds of factors including stuff like how much fuel do I need if I can't land at my nominated backup airport and have to go to a secondary backup airport.
Domestically, checked baggage can fly even if you don't. It depends on the situation.
> Domestically, checked baggage can fly even if you don't. It depends on the situation.
I could be wrong about it being illegal, I was just repeating what an (other) airline employee told me. But they did take my luggage off the plane after telling me that they weren't going to.
It's weird to me that they unloaded anything in the hold for what should have been a refuel-and-go. Unless they're expecting you to be held on the ground for 3+ hours, they typically don't even bother getting the pax out much less the bags.
Just to be clear, when you say you "glided" are you saying that you ran out of fuel? Because if it did actually run out of fuel there should be a report about it somewhere and I'm really interested in finding it or why it somehow doesn't exist. If they ran *low* on fuel, that is something else entirely.
EDIT: Looks like everyone else jumped on this at the same time. lol.
There's no possible way the story is true as relayed by the parent. If the flight was indeed forced into a situation where there was an unpowered glide into landing, that airframe and crew would both be grounded for some time, not turned around and put back out for the continuance of the flight.
Every incident has to go into the carrier's safety reporting system which is then followed up by the FAA and/or NTSB. Even stuff as simple as a flight attendant feeling fatigued after not getting enough rest goes into the SRS.
I don't think the public has access to the SRS but the FAA and NTSB do.
I have no way of knowing whether or not the plane ran out of fuel. I'm assuming they kept some fuel, e.g. in case they didn't stick the landing on the first attempt.
The plane did not run out of fuel. If the plane had run out of fuel, the flight crew would have prepared you for a potential crash landing. There would be no question whatsoever. It would have made national news. The plane and crew would have been grounded pending investigation by the airline and the NTSB, and not gone on to resume its journey shortly thereafter. Hell, everything else aside, it would have sat dead on the runway, unable to taxi, while passengers disembarked on the inflatable slides.
Your plane had plenty of fuel. It followed established procedure where they waited for as long as they could, diverted when the fuel situation warranted a change of plans, and landed at the alternate airport with more than enough fuel for at least one go-around and likely two.
In principle this is true. In practice, without the engines on you don’t have hydraulics which means no anti-skid and the pilots have to stomp on the brakes. This means overheated brakes and popped tires, almost certainly starting small fires that will warrant the slides.
There is, as others pointed out if a plane runs out of fuel there are reports, hearings, investigations. Nothing goes that wrong in modern commercial aviation, pretty much anywhere in the world, without being seriously looked in.
What happens if you don't go into the 2nd flight? I wouldn't, personally, as someone who are not fan of flying. Is Pittsburgh far enough from Washington to not take a bus?
> What happens if you don't go into the 2nd flight?
They took my luggage off the plane and United agreed to put me on the next flight to my final destination for free even though tickets were $750 that day.
If you can find the specific flight in a log online somewhere, you might be able to find the pilot and bring some sort of legal action... if you're lucky, a lawyer might send a letter for the lolz if they offer you a settlement.
there is no proof that anything the crew said over the PA was literally true. They should be honest about their plans ("we should me at the destination shortly" or "we're diverting to XYZ now") but the particulars of fuel management and the regulations are not digestible to the layperson.
Hell, I had to unpack them & explain them to the pilots every once in a while. (They'd often form some interpretation that worked out "best" ... for them personally).
In situations where there many diversions, sometimes secondary airports either get too busy to accept additional A/C or run out of space or crews to deal with them.
Sure, that makes sense. Does that likely mean there were other flights with even less fuel that had to land ahead of this plane, or how do they triage that situation? It seems like a failure to triage properly if one plane has to glide, but maybe I'm naive about how close all of the other planes are to gliding.
Planes diverted to Columbus until they couldn’t accept any more diversions, at which point the rest diverted elsewhere. If any planes had a genuine fuel emergency where Columbus was the only option, other planes with more fuel would have been rediverted elsewhere.
"A crew of engineers from Winnipeg airport clambered into a van and headed for Gimli to assess the damage. During transit, however, their vehicle unexpectedly ran out of fuel, nearly ripping a hole in the delicate space-irony continuum."
Another good one: “Many of the crew members were keenly aware that jumbo jets such as theirs were not designed for dead-stick flight — let alone dead-stick landings. In all probability, their inevitable confrontation with the Earth would not be an improvement on their current situation.”
Also, "First Officer Quintal caught sight of the fleeing families, but it was far too late to revise their landing plans, so he opted not to distract the captain with the unsettling discovery."
And "Some grizzled old pilots swear that sometimes, when the wind is just right on a quiet night, you can just about make out the double-engine-failure BONG! as the old girl is flying by; and if you’re very lucky, you might catch the faint odor of damp pilots in the air."
"The Guide says that there is an art to flying,” said Ford, “or rather a knack. The knack lies in learning how to throw yourself at the ground and miss.” He smiled weakly. He pointed at the knees of his trousers and held his arms up to show the elbows. They were all torn and worn through.
“I haven’t done very well so far,” he said." - Douglas Adams, HHGTTG
The "not designed for dead-stick flight" is a bit off. Of course they are not designed to be gliders, but they are designed to be efficient, which means they have a reasonably high lift/drag ratio (in the range of 15–20 for most airliners). They glide quite well.
Indeed, it suprises people that light aircraft generally have a glide ratio comparable with a brick, whilst airliners are generally quite efficient given the incredible size.
> Despite the lack of time, Moody made an announcement to the passengers that has been described as "a masterpiece of understatement":
> > Ladies and gentlemen, this is your captain speaking. We have a small problem. All four engines have stopped. We are doing our damnedest to get them going again. I trust you are not in too much distress.
I once read something by... someone... EM Forster, maybe? About how a key difference between the British and the French is that, in an emergency, the French may handle it capably enough but will be freaking out the whole time—then carry on like it never happened; while the British will be cool as a cucumber and act like a life-and-death emergency is a minor inconvenience as they handle it, but then never shut up about it for the rest of their lives.
[EDIT] I wanna say the example was a mishap on a ride somewhere, and he wrote something to the effect of "by the time they get where they're going, the French will have forgotten all about it, while the English will only have just begun what will become an excited, endless retelling of the tale". Except I'm sure he worded it better. Fairly sure it was Forster. Somewhere in his (extensive) essays and articles, I think.
Cultural factors are given significant weight in air accident investigation and safety. For instance, the Korean Air disaster was put down to a cultural subservience to authority.
the Korean Air disaster was put down to a cultural subservience to authority
Here's my anecdote. My mother was born in Korea. At one point, she literally told me that it doesn't matter if I you are right, your duty to your elders comes first. (EDIT: I think it bears saying: A huge number of family arguments in Korean-American families have something to do with parents ruining their credibility with intelligent children by saying such things.)
Air safety is important enough to be given a woke pass!
Fidelity to objective truth is far too important and fundamental to ever be compromised on. In fact, I would go so far to say, that "compromises" on fidelity to objective truth are a red flag, that some form of power corruption is going on.
Another form of corruption, is a claim to be the ultimate or sole arbiter of truth. No being who is subject to the Laws of Thermodynamics and Landauer's Limit should be able to claim they should be treated as effectively omniscient.
No one is inherently right. The best we can do, is to always strive to be less wrong.
The British culture contains NO MORE stoicism, "manhood", "stiff upper lip" or whatever you would call it than any other culture. Saying such stems from imperialism
That's right, every single culture ever has been exactly the same, with exactly the same traits and emotions distributed in equal proportions across the entire population.
Forster was British and was poking fun at his own national character (if it wasn't him it was... Maugham, I suppose? Definitely British). You'll note how it's not really clear they come of better-seeming, overall, and the "punch line" amounts to a complaint about the British. [EDIT: and, go figure, another common characterization of the British is that their humor is often this sort of thing]
And there's usually something to those stereotypes, even if assuming they're true of everyone is plainly not a great idea.
I was on a flight and after a rough turbulent half hour after take off, the English captain announced a technical issue that meant we must return to the airport.
The plane had been acting bizarrely it bounced very hard on take off and then did not gain much altitude for the duration.
There was another rough half an hour back to land in a terrible cross wind.
Then a few moments on the tarmac before it was announced that it was because additional checks were required and the plane was running entirely fine. A bird strike meant they had to return as a precaution.
I'd take the clear and transparent understatement over what I can only assume is a corporate line which covers things from entirely not worth mentioning and we're about to crash and burn.
> When a stereotypical airplane (or spaceship) pilot speaks over the radio, either to flight controllers on the ground or to his own passengers, he does so in a very soft, smooth register, just barely loud enough to pick up on the radio, probably with a faint American Southern accent (unless he's British, in which case it is an upper-class one). He uses radio jargon, even when he doesn't really need to. A true Danger Deadpan never loses his cool or changes his tone of voice under any circumstances whatsoever, a habit which is often Played for Laughs. ...
> In Real Life, this makes a lot of sense. Even if your plane's lost two engines and half a wing, the last thing you need is a bunch of scared people in the back of the plane panicking and raising hell; you can't be screaming "OH GOD WE'RE ALL GONNA DIE" over the radio. Not to mention the fact that if you stay calm and actually tell Mission Control what the problem is, you won't throw away what may be your last chance to actually work out how to fix it or at least get to the ground in one piece.
The "Real Life" section includes Yeager (with a long quote from The Right Stuff with an example of the voice) and Moody of BA Flight 9, plus many others, and comments:
> Yeager is the most known example and the book "The Right Stuff" made a nice legend, he probably isn't the first who started to talk that way. For example, Mark Gallai (a Soviet test pilot who started his career in the 1930s) recounts just this way of reporting over radio about as soon as radio was introduced on airplanes. Let's just repeat: when you need to report your condition to ground crew, you are going to speak calmly and clearly, no matter what's happening with your plane.
I'd wondered when "English understatement" and the similar "British understatement" came into being. Seems strongly correlated with the outbreak of WWII, :
War historian Antony Beevor discussed that stereotype thusly:
''Patriotism also permeated those British war movies of the 1950s and 60s – The Dam Busters, Reach for the Sky, The Cruel Sea, The Heroes of Telemark, The Battle of the River Plate, Cockleshell Heroes. It camouflaged itself in self-deprecation, but the rousing march music in the finale always braced our belief in the rightness of our cause. We have long made fun of all the period cliches, unable to believe that anyone talked like that. But when researching my new book Arnhem: The Battle for the Bridges, I found that German officers really did say to the British paratroopers taken prisoner: “For you the war is over.” One of my favourite remarks, recorded at the time by a junior doctor, is the reaction of Colonel Marrable, the head of an improvised hospital in the Netherlands, when Waffen-SS panzergrenadiers seized the building. Still puffing gently on his pipe, he says to his medical staff: “Good show, chaps. Don’t take any notice of the Jerries. Carry on as if nothing has happened.” I have always been doubtful about the notion of “a national character”, but a national self-image certainly existed during the war and for some time afterwards.''
The Algolia search box here on HN shows a ton of previous ''Gimli Glider'' submissions as it was a legendary feat of airmanship, and another Canadian pilot made an equally astonishing deadstick airliner landing in 2001:
A joke amongst NATO pilots comparing Canadian aviators, with their limitless air space, and their European allies, with their comparitively tiny national air spaces:
''Europeans: afterburners off after 3 minutes. Canadians: afterburners off after 3 countries.''
"A crew of engineers from Winnipeg airport clambered into a van and headed for Gimli to assess the damage. During transit, however, their vehicle unexpectedly ran out of fuel, nearly ripping a hole in the delicate space-irony continuum."
Facepalm
"However, unbeknownst to the pilots and the fuel crew, this multiplier provided the weight in imperial pounds; the new, all-metric 767 was based on kilograms, and required a multiplier of 0.8. As a consequence of this documentation disconnect, Flight 143 had left Montreal with roughly half the necessary fuel."
The nose gear, however, dangled limply from its housing.... In addition, had it not been for the drag created by the collapsed front gear, the powerless plane would have plunged into the crowd of spectators, sowing destruction and death in its wake.
So a product defect that saved lives. I wonder if there other examples
Mayday Air Diasater has a full episode on this incident. In short, the pilots heroic effort led to safe landing on an old airfield converted into drag strip.
Meanwhile, a car mechanic's stories would make people worry about driving, once you realize how many badly-maintained vehicles driven by morons are hurtling down the highway at 73 mph.
Fortunately, most aircraft crashes happen due to multiple, uncorrelated failures lining up to cause a disaster.
73 MPH? Must be a leisurely Sunday church drive (at least here in the Atlanta metro, where cars engulfed in flame on the side of the interstate are not as rare as they should be).
Yeah, that's a fair point. But if things are flowing I regularly see 80+ (which probably lends itself to eventual 20 MPH when someone wrecks and causes awful traffic).
Definitely don't mind those late night drives, as long as you keep an eye out for people not signaling or not having their lights on.
It'd be awesome if we could invest in actual public transport instead of more lanes but...
I think the general principle is that the less control you personally have over the means of transportation, the more liability rest with others, and therefore the more checklists, procedures, and redundancies there are in place to protect you.
Very safe: trains and subways, buses, passenger aircraft, rollercoasters, elevators
As the Admiral Cloudberg article mentioned above notes, it was actually a metric (liters) to metric (kilograms) conversion error. (Plus fuel gauges that failed in an unsafe mode, and flying with clearly broken fuel gauge.)
The sad part of that is people continuing to learn the wrong lesson. The real issue with the orbiter was not the specific unit systems, it was assuming a contractor followed specifications perfectly, not testing properly before launching it into space where it can't be fixed, and then ignoring the people who noticed the issue until it's too late to try anything because they didn't fill out the correct paperwork. Using MKS and CGS together could cause the exact same issue entirely in metric.
This is the problem when North Americans, especially US-Americans, argue that their country "is metric" because the inch is defined as 2.54cm, and science and some engineering uses metric units.
People lack day-to-day familiarity with the units, so what should be obvious mistakes go unnoticed.
Where did the 71 come from? The US inch was 2.54000508 cm and the UK inch was 2.5399977, until the Johansson's blocks convinced everyone to use the industrial inch of exactly 2.54 cm - what is now called the "international inch" (1ft = 0.3048 meters).
A nautical mile corresponds to 2.9229 cm. A survey foot is not much different than an international inch. I hope there's some oddity of history I'm missing!
Bryan Cantrill draws some excellent parallels between this incident and software systems in his "Debugging Under Fire" talk (beware of semi-automated systems):
Beautifully written. A perfect balance of story telling, facts, embellishments. Idiosyncratic style with a point to convey. I feel this is the kind of thing that will outlive AI generated text.
I see from skimming other comments that this is widely shared sentiment.
With so many recorded errors of conversion, you’d assume we would just make it intergalactic law that everybody use metrics. Why is the imperial system still used, especially when it’s by such a small minority?
There must be a way to calculate the weight of an aircraft from the flight characteristics and from that get an idea of how much fuel the plane has. Maybe not 40 years ago...
I think it should be possible to ballpark it. Use some statistical averages as well as the different positions for the weight to come up with a probability distribution function.
Fuel load is ~50% of the total takeoff weight of a commercial jetliner, which is to say, even a rough inertial estimate could well be in the right ballpark.
Roughly, for each passenger there's an equivalent mass of fuel on the plane.
If you're working with thin margins that might not be enough, but if someone's shorted the craft half its fuel load, as was the case for AC143, I'd suspect this would be evident.
I mean the way we'd do it is a series of sawtooth climbs, since weight typically has a profound effect on climb performance.
Other than a nerd-sniping exercise I don't see the point of going down this rabbit hole, because on an aircraft with pax the pilot's job isn't to screw around playing Chuck Yeager and estimate fuel with test pilot techniques.
If they can't fly with confidence that they're safe, then the pilot's job is to put the fucking aircraft on the ground as soon as able.
I was thinking more of a secondary passive reading done by a computer in the background to catch the simple cases where the plane is unusually light for the entered distance.
A few weeks ago, I found the film Flight (2012) by Robert Zemeckis, starring Denzel, with John Goodman as a coke dealer. It was free to watch on YouTube.
The film is mostly human drama, but the first fifteen are a really gripping, suspenseful depiction of the air disaster at the center of the plot, from the cockpit view. And it's based on a real-life incident. I enjoyed the whole thing, and the aviation part really pulled me in.
This is a perfect example of the swiss-cheese model of accident causation. If any of the following were different there would not have been an issue: the fuel gauge was working, the pilot or co-pilot caught the fueling error, or the aircraft was grounded due to the fuel gauge being inoperative.
Author does a great job of capturing the anxiety the captain and crew felt and the poise they demonstrated. Maybe my favorite line, "Quintal’s cucumber-cool support".
If a plane of this had graphene strips on it, that could unravel and have static charge opposit to the earth. How long would that "parachute" have to be, how heavy would it be?
Is that really true? My commercial airline pilot uncle didn't fly a glider until after he retired, but that's just anecdata.
I used to follow Patrick Smith, aka "Ask The Pilot". He didn't start with a glider.
Now I follow Scott Manley. He just got his private pilot license, and did not start with a glider. Nor did my missionary pilot uncle. Nor did a co-worker of mine who was learning to fly.
E.g. gliding is really big in Germany where it gained popularity especially after WWII.
It's fairly cheap and usually organised as hobby clubs instead of commercial schools.
For example a club in my area offers young people, ages 15-25, flying lessons until their first solo for a flat fee of 400€.
Many people who are interested in aviation use this to get their first piloting experiences while still in school. Some then take the next step of becoming commercial pilots.
Motorised flight on the other hand is much more expensive and (on a private level) done by people who, usually, already have a (well paying) job.
A lot of USAF pilots flew gliders at the USAF Academy, or as cadets in Civil Air Patrol. At some point in their career, they become airline pilots. It would be similar for the RCAF.
I'm wildly curious if you know more about this particular point in time, but knowing Vg of your plane and being able to perform (and know when to perform) a forward slip to land is something most pilots today learn before they ever fly solo, much less get a license that permits them to fly passenger jets.
Struggling to see what glider knowledge applies here (other than, perhaps, glider pilots slip to land more frequently since it isn't like they have power to remove).
That was so well written. It was just such a pleasure to read.
Makes me think about a comparison video regarding ADHD that had the same student recorded while watching: A) a math video, and B) Star Wars.
I think one thing all humans need, is a bit of the ol' campfire-esque narrative. We need a good story. We love to be told one. So, maybe the trouble is not math per se, it's that nobody (or almost nobody) is teaching math with some kind of the right narrative approach.^0
This story contained a lot of technical and detail information, but I find it all easy to recall (not that I have much trouble most of the time), but I didn't waver in reading this. I was glued to it the whole way through. I didn't just get the story, I got the analysis, the why, and the details. In a single read, that happened without distraction.
And I loved it. It feels satisfying. I didn't realize I was learning, but learning was the natural consequence of being told a great story.
So I think that you can make anything teachable as long as you can teach it using the right narrative vehicle.
0: I know not everybody has trouble learning without narrative. Some people can "create their own adventure" armed with only a textbook, and work their way through it in the idiosyncratic order and style that best suits their individual "wiring". I know that not everybody has trouble learning STEM (I didn't, when I worked at it myself), but I know lots of people do. And I find myself being distracted so easily when studying some technical videos or content, but not others. That's also common. What I think is that every human evolved to learn in "roughly" the same way, in the same sense that we "all" have capacity for spoken language, I think we all have "an innate superpower" to learn things delivered on the right narrative vehicle. We evolved to communicate orally, "around the campfire" as the euphemism goes. This wasn't just entertainment, it was how small tribes of us survived, learned together, and structured and ordered their world to ensure survival. So, it's vital. I think we can make almost anything teachable to almost anyone, if it has the right narrative. I think so many people think "I'm no good at math", or "I couldn't be a programmer", or programmers think "I don't get art" or "I'm no good at psychology" or whatever. I often feel a twinge of sadness, because it seems like they're missing out when they shouldn't be. I feel like shaking their shoulders like a mad person and saying, "Of course you can!" in the kind of crazed-Gatsby-esque way that Jay is convinced, “Can't repeat the past? Why, of course you can!” Except I'm not crazy. I'm sure this is a thing. I'm sure that in future, we will figure out how to deliberately deploy this innate narrative technology we all come with to make learning of everything more efficient! :)
> presumably because a simultaneous engine failure had been too ridiculous for Boeing engineers to contemplate
This is hard to grasp, esp. given the presence of a RAT. You're giving engineering time to add a device specifically made to handle loss of all engines, but don't spend the time to write the corresponding procedure?
> ...had determined the fuel weight by multiplying the the number of dripsticked liters by 1.77, as indicated by the documentation. However, unbeknownst to the pilots and the fuel crew, this multiplier provided the weight in imperial pounds; the new, all-metric 767 was based on kilograms, and required a multiplier of 0.8
Darn, how many of these incidents will we require until we finally get rid of the metric system once and for all!
> The internal investigation into the incident laid the blame partially upon Captain Bob Pearson and First Officer Maurice Quintal, who should have observed the Minimum Equipment List (MEL) and grounded the aircraft since it lacked functioning fuel gauges
This is an interesting take - and as the pilot of the plan it certainly should rest on you that you're responsible for all to be in working conditions before you leave. However combining that it was apparently a frequent failure, with the corporate culture that's outlined, it's a good cautionary tail about resisting the pressure when something's wrong but "everybody's doing it anyways".