How does someone get to a position where that's a risk without knowing about that risk? Surely aircraft fueling is a completely standardized process where only one unit is ever used?
At first I was unsure, because it's been a while back, but 1983 was 25 to 30 years after Tu-107 and Boeing 707 went into service. They absolutely should have had standardised processes already by then.
1e5? Jesus that a lot of fuel in a day. Blows my mind how much shit is in the earth that we can just run those numbers and its not even that much in the grand scheme of things
It probably became that after this incident yes. So many of processes and procedures are out in place because we learned they are necessary after something went dramatically wrong.
Not quite, this was around the time aviation was moving from imperial to metric. Fuel is also loaded by volume, but calculated in weight, so the fueling operator at the airport accidentally used the imperial conversion factor, and the mistake was not picked up as the fuel gauge on the plane was faulty.
Look up "The Gimli Glider" for more on this, the plane (and crew) became quite famous.
I also wonder if there could be some sort of fuel gauge in an aircraft, possibly even a little warning light that comes on if you're attempting to take off with less than half a tank
Planes very often have less than a half tank. It takes fuel to move fuel so airplanes only cary enough fuel to get to their destination, and enough reserves to get to an alternate airport.
It appears more importantly that the system for both fuel gauges had been glitching for weeks and the redundant fuel gauge circuit had already long been out of operation. They didn't replace it because the backups in Canada all had to be sent back to be refurbished, and they were allowed to be in the air without a backup fuel gauge.
A bunch of very minor miscommunications happened between technicians verifying the issue, and the pilots repeating the issue to new crews, so that the final pilots to fly it thought they were told that the plane had already been approved to fly with no fuel gauges in flight; they weren't functioning as soon as they started the plane, before they got in the air.
Kinda nuts, since all of these were issues that themselves would not be a problem; and when combined to be a problem, they would notice before they got off the ground, which they did, but thought it had already been ok'd from some minor miscommunications (the new crew even followed all procedures to check it with log books and confirm verbally about the system with technicians, but left out crucial details so thought they were talking about the same problem: one gauge being faulty versus both).
So all that happens before the egregious mistake in filling; and that even required a manual direct check of tanks (due to the faulty gauge) which was also negated by these minor communication failures.
(Also crazy is that the ground engineer and the flight crew all had to mess up the metric conversion factor (because they confirmed each other), and educated people like those did not stop to think that 1.7 kg/L is absurdly dense for a watery liquid like kerosene. It's an easy mistake if you're not paying attention, but multiple people made the mistake simultaneously.)
You get it in intro chemistry. Water is 1. It's not deep familiarity, and I can't imagine specific gravity wasn't taught in the 80s.
Anyway, it's an easy thing to ignore. The point is that it's a multiple of simultaneous failures, all of which are individually also low probability, but multiplied by the very high number of flights.
Agreed; they ran out of fuel because lots of people made small mistakes that happened to line up.
I’m familiar with chemistry and water’s status as the density identity. But these are airline pilots who likely didn’t use metric at all in their education or training. They were introduced to the use of metric via conversion charts, and only recently before this accident. I’m confident that if you asked them the density of water, they would either have shrugged or quoted “a pint’s a pound the world around.”
Sorry but I'm not convinced that in the 60s and 70s kids in high school did not learn that the specific gravity of water is 1. The pilots further went to some amount of college and took at least a basic science requirement.
It's 1. ONE. It's not some metric magic that you never learn in America (even though you do learn and use metric in science class, even in ye olden tymes).
Again, it's easy to not make the connection that something is off when there's a bunch of stuff going on, or maybe all your other manuals say you should still be in imperial/customary still, so it's understandable to miss. But it's inconceivable that the pilots would not know the metric density of water. It's further quite unlikely that the pilots, having gone through pilot training and driven cars and carried around gas cans and all, would not have some basic understanding that petroleum fuels and oils have density near that of water too.
In the US in the 90s, I learned relatively little metric in high school. Basic measures, yes (meters, liters, joules, kg), but I don’t remember learning that water is 1kg/L (I think I learned that during my engineering degree in college). I do remember learning that the energy to heat 1cc of water 1°C is one Joule.
Just an anecdote, but I wouldn’t be so confident if I were you.
One calorie. But seeing as you took chemistry and learned basic calorimetry and clearly forgot most of it, I'm guessing you would have forgot learning the specific gravity of water. That's fine, if you don't continue science classes in college.
But again, these are pilots who would have continued with this kind of thing. As you continued science/engineering in college yourself, you (re)learned the density of water. Or you retained knowledge from HS and forgot you learned it in HS, just as you forgot about the calorie, I dunno -- memory is weird.
I don't know these guys, I don't know aviators in the 1980s, so I perfectly well could be wrong. But my understanding of what was taught in schools at the time is that, again, if they had retained knowledge of what they did learn, and they were aware they were working in metric, and they were paying attention, then they should have sanity-caught that 1.77 was absurd, regardless of whether metric was used previously for their airline.
Because at that time Canada just went metric and everyone experienced doing it learned imperial then they were required to do it in metric you were expected to use the right conversation factor.
A lot more went wrong here. The fuel gauge was broken but they knew they in advance and could fly without it as long as the correct amount was loaded - which it wasn’t!
This is in a book about math errors with real-life impacts that I have. It wasn't simply a matter of the wrong amount of fuel. There was a whole series of redundant safety measures that would each have caught the problem. Every single one was disabled or failed for one reason or another.
They tried reproducing the scenario in simulators and not a single other crew could land that plane safely. The people on board were extremely lucky the pilots they happened to have on that flight were experts
Our physics teacher drilled this into our heads. He said you’re never safe if you’re relying on people to get everything right and used this exact event to illustrate his point
Aircraft fuel is measured by weight because the density can change with temperature. It important to have a known energy potential loaded into the aircraft.
If they weighed the fuel, did they put the tanker on a weigh bridge, before and after tanking the aircraft. Most fuel tankers have a fuel gauge, just like a servo pump.
How does someone get to a position where that's a risk without knowing about that risk? Surely aircraft fueling is a completely standardized process where only one unit is ever used?
Happens to the best of us.
https://www.simscale.com/blog/nasa-mars-climate-orbiter-metric/
This is less surprising to me, that is more one-off. 1e5 airplanes are refueled every day, the routines must be absolutely set in stone.
At first I was unsure, because it's been a while back, but 1983 was 25 to 30 years after Tu-107 and Boeing 707 went into service. They absolutely should have had standardised processes already by then.
1e5? Jesus that a lot of fuel in a day. Blows my mind how much shit is in the earth that we can just run those numbers and its not even that much in the grand scheme of things
It probably became that after this incident yes. So many of processes and procedures are out in place because we learned they are necessary after something went dramatically wrong.
Not quite, this was around the time aviation was moving from imperial to metric. Fuel is also loaded by volume, but calculated in weight, so the fueling operator at the airport accidentally used the imperial conversion factor, and the mistake was not picked up as the fuel gauge on the plane was faulty.
Look up "The Gimli Glider" for more on this, the plane (and crew) became quite famous.
I also wonder if there could be some sort of fuel gauge in an aircraft, possibly even a little warning light that comes on if you're attempting to take off with less than half a tank
Planes very often have less than a half tank. It takes fuel to move fuel so airplanes only cary enough fuel to get to their destination, and enough reserves to get to an alternate airport.
It was broken on this flight.
They were both broken
This was right after Air Canada switched to metric.
https://youtu.be/4fGibq7OV6E
It appears more importantly that the system for both fuel gauges had been glitching for weeks and the redundant fuel gauge circuit had already long been out of operation. They didn't replace it because the backups in Canada all had to be sent back to be refurbished, and they were allowed to be in the air without a backup fuel gauge.
A bunch of very minor miscommunications happened between technicians verifying the issue, and the pilots repeating the issue to new crews, so that the final pilots to fly it thought they were told that the plane had already been approved to fly with no fuel gauges in flight; they weren't functioning as soon as they started the plane, before they got in the air.
Kinda nuts, since all of these were issues that themselves would not be a problem; and when combined to be a problem, they would notice before they got off the ground, which they did, but thought it had already been ok'd from some minor miscommunications (the new crew even followed all procedures to check it with log books and confirm verbally about the system with technicians, but left out crucial details so thought they were talking about the same problem: one gauge being faulty versus both).
So all that happens before the egregious mistake in filling; and that even required a manual direct check of tanks (due to the faulty gauge) which was also negated by these minor communication failures.
(Also crazy is that the ground engineer and the flight crew all had to mess up the metric conversion factor (because they confirmed each other), and educated people like those did not stop to think that 1.7 kg/L is absurdly dense for a watery liquid like kerosene. It's an easy mistake if you're not paying attention, but multiple people made the mistake simultaneously.)
That kind of natural intuitiveness only comes from deep familiarity with, and confidence in, the metric system. None of these people had that.
You get it in intro chemistry. Water is 1. It's not deep familiarity, and I can't imagine specific gravity wasn't taught in the 80s.
Anyway, it's an easy thing to ignore. The point is that it's a multiple of simultaneous failures, all of which are individually also low probability, but multiplied by the very high number of flights.
Agreed; they ran out of fuel because lots of people made small mistakes that happened to line up.
I’m familiar with chemistry and water’s status as the density identity. But these are airline pilots who likely didn’t use metric at all in their education or training. They were introduced to the use of metric via conversion charts, and only recently before this accident. I’m confident that if you asked them the density of water, they would either have shrugged or quoted “a pint’s a pound the world around.”
Sorry but I'm not convinced that in the 60s and 70s kids in high school did not learn that the specific gravity of water is 1. The pilots further went to some amount of college and took at least a basic science requirement.
It's 1. ONE. It's not some metric magic that you never learn in America (even though you do learn and use metric in science class, even in ye olden tymes).
Again, it's easy to not make the connection that something is off when there's a bunch of stuff going on, or maybe all your other manuals say you should still be in imperial/customary still, so it's understandable to miss. But it's inconceivable that the pilots would not know the metric density of water. It's further quite unlikely that the pilots, having gone through pilot training and driven cars and carried around gas cans and all, would not have some basic understanding that petroleum fuels and oils have density near that of water too.
I can’t speak for Canada in the 60s.
In the US in the 90s, I learned relatively little metric in high school. Basic measures, yes (meters, liters, joules, kg), but I don’t remember learning that water is 1kg/L (I think I learned that during my engineering degree in college). I do remember learning that the energy to heat 1cc of water 1°C is one Joule.
Just an anecdote, but I wouldn’t be so confident if I were you.
One calorie. But seeing as you took chemistry and learned basic calorimetry and clearly forgot most of it, I'm guessing you would have forgot learning the specific gravity of water. That's fine, if you don't continue science classes in college.
But again, these are pilots who would have continued with this kind of thing. As you continued science/engineering in college yourself, you (re)learned the density of water. Or you retained knowledge from HS and forgot you learned it in HS, just as you forgot about the calorie, I dunno -- memory is weird.
I don't know these guys, I don't know aviators in the 1980s, so I perfectly well could be wrong. But my understanding of what was taught in schools at the time is that, again, if they had retained knowledge of what they did learn, and they were aware they were working in metric, and they were paying attention, then they should have sanity-caught that 1.77 was absurd, regardless of whether metric was used previously for their airline.
They were taught imperial, where water is 62.4 lb/ft3 instead of 9807 N/m3
Damn, it's easy to forget just how primitive the world was not even a century ago
Because at that time Canada just went metric and everyone experienced doing it learned imperial then they were required to do it in metric you were expected to use the right conversation factor.
https://youtu.be/4fGibq7OV6E?si=PfuTXFl-792XSb81
This video explains it in detail
A lot more went wrong here. The fuel gauge was broken but they knew they in advance and could fly without it as long as the correct amount was loaded - which it wasn’t!
You’d think so but alas, no
This is in a book about math errors with real-life impacts that I have. It wasn't simply a matter of the wrong amount of fuel. There was a whole series of redundant safety measures that would each have caught the problem. Every single one was disabled or failed for one reason or another.
They tried reproducing the scenario in simulators and not a single other crew could land that plane safely. The people on board were extremely lucky the pilots they happened to have on that flight were experts
What’s the book called?
"Humble Pi: When Math Goes Wrong in the Real World" by Matt Parker
Found a copy, ordered immediately.
The Gimli Glider!
I have a Plane Tag made from it's skin.
This is what happens when americans work outside of the US
It happened because Air Canada bought their new planes in metric since the Canadian government itself is switching to metric units at the time
This was a Canadian owned plane operated by Canadian pilots on a Canadian route, why do you blame the Americans
TECHNICALLY, Canada is in America.
The Gimli Glider
https://en.wikipedia.org/wiki/Gimli_Glider
Several layers of things went wrong
r/USdefaultism
Nice
Our physics teacher drilled this into our heads. He said you’re never safe if you’re relying on people to get everything right and used this exact event to illustrate his point
Next time use a metric volume, litres or cubic metres.
Aircraft fuel is measured by weight because the density can change with temperature. It important to have a known energy potential loaded into the aircraft.
Wow no one ever thought of this! Except for you! A Redditor with a random comment! I’m sure there was absolutely no reason they used weight
If they weighed the fuel, did they put the tanker on a weigh bridge, before and after tanking the aircraft. Most fuel tankers have a fuel gauge, just like a servo pump.
[deleted]
Only in American domestic flights. International aviation all use metric.
I love how it's obvious that the original commenter has never left the country.
Ouch
British units? Doubt.
Time for you to take aviation class in college