11 ms·

Gimli Glider

176 points by lelf 13y ago

crystalmace 13y ago
I was at that airfield last summer for a cadet course (I'm an air cadet) and I'll be going again this summer to get my glider pilot's licence; just like the pilot of the Gimli Glider did so many years ago! I can't wait!
- techwatching 13y ago
  Yay Manitoba! Winnipeg here.
  - ahelwer 13y ago
    As long as we're sounding off, I grew up in Brandon. I'm over in Seattle now, though. What's the tech sector like in Winnipeg these days?
    - techwatching 13y ago
      Its low key. There's a very active design community, but comparatively limited startup activity.
- efm 13y ago
  The pilot (or co-pilot), I don't recall, was also an Air Cadet at that airfield, which is how he knew that it was there, a good long strip, and well maintained.
  - crystalmace 13y ago
    Yes, and he was a glider pilot in the air cadet program which aided to his ability to properly land the plane without engines
    - seanmcdirmid 13y ago
      The pilot was a glider pilot, the first officer was an air cadet, and the field was already turned into a race track.
eddanger 13y ago
I hope the Americans don't use this as an excuse to stick with their old school system. I guess in one way they are closer to the Kingdom of England than us Canadians are.
- johansch 13y ago
  China uses metric. Just wait a decade or two...
  - untothebreach 13y ago
    I really can't wait for us to start using a sane system. While we're at it, could we also start writing our dates in a sane way? Putting the month before the year is beyond ridiculous.
- m_mueller 13y ago
  After reading the whole article I'm convinced that learning metric from primary school age up would have avoided this accident. "In this case, the weight of a litre (known as "specific gravity") was 0.803 kg. (...) Between the ground crew and pilots, they arrived at an incorrect conversion factor of 1.77, the weight of a litre of fuel in pounds." See, here's where metric system sanity checks become relevant, that are simply not possible with imperial because nothing is compatible with each other. In metric, I just know, without any conversion factors to memorize, that 1kg water equals 1l at room temperature. Everyone with high school education should also know that gasoline products are lighter. Now I can do a sanity check - since the weight of one liter should be less than 1kg, there's no way 1.77 is right. If two well educated people do this math, at least one of them should see the mistake.
- Patrick_Devine 13y ago
  In the aviation world it's really mixed. ICAO uses imperial and metric measurements for different things. Feet are used for altitude and knots for distance, but temperature is always measured in centigrade. It's convenient to use feet because planes are stacked in 500' increments and not 152.4m increments. VFR (visual flight rules) flights are usually on the 500's (eg. 3500', 4500', etc. depending on heading) whereas IFR (instrument flight rules) flights are on the 000's (4000', 5000', etc.). Knots are convenient because 1 knot is equal to 1 minute of 1 degree of arc on a great circle. If you're flying anywhere far away this ends up being important as a great circle is the shortest route between any two places. Oddly enough, the metric system is useful with temperature because the standard lapse rate is 2 degrees per 1000' of altitude. So if you had to climb from 6000' to 8000' on an IFR flight plan, you would usually drop 4 degrees centigrade, which might be significant if it was raining out and it dropped below freezing. Having water on your wings and climbing up to an altitude where it's freezing is going to make you have a really bad day.
shruubi 13y ago
I'm guessing OP is a fan of Smodcast. http://smodcast.com/episodes/true-tales-of-canadian-heroism/ http://smodcast.com/episodes/true-tales-of-canadian-heroism/
bjg 13y ago
I'm curious if the submitter has been listening to SModcast[0]? They had a few episodes on the Gimli Glider recently. [0] http://smodcast.com/channels/smodcast http://smodcast.com/channels/smodcast
shadeless 13y ago
I heard about this recently on smodcast (podcast featuring Kevin Smith and his producer Scott Mosier), their reenactment was hilarious and I heartily recommend it - http://smodcast.com/episodes/true-tales-of-canadian-heroism/ http://smodcast.com/episodes/true-tales-of-canadian-heroism/
Karellen 13y ago
Ah yes, The Fundemental Failure Mode Theorem[0] at work: Complex systems usually operate in failure mode. Or, "That's why I'm skeptical of people who look at some catastrophic failure of a complex system and say, "Wow, the odds of this happening are astronomical. Five different safety systems had to fail simultaneously!" What they don't realize is that one or two of those systems are failing all the time, and it's up to the other three systems to prevent the failure from turning into a disaster." [1] [0] http://en.wikipedia.org/wiki/Systemantics#System_failure http://en.wikipedia.org/wiki/Systemantics#System_failure [1] http://blogs.msdn.com/b/oldnewthing/archive/2008/04/16/8398400.aspx http://blogs.msdn.com/b/oldnewthing/archive/2008/04/16/83984...
- arnorhs 13y ago
  The more fundamental thing to think about is: - what are the total number of failures that can happen? - what is the probability of those failures occurring - how many sets of those can combine into a catastrophic failure? And then from those numbers you can derive the probability of a catastrophic failure occurring.
  - Karellen 13y ago
    Yes, but the thing that the Fundamental Failure Mode Theorem tries to draw attention to is "what is the probability of those failures occurring". i.e. it's possible that some of those failures have already occurred, and you just haven't noticed because the redundant systems are being redundant and preventing the overall system from failing catastrophically. Or you have noticed, but think that the redundant systems are sufficient, not realising how much closer they bring you to a single point of failure. So the probability of your whole system failing are higher than you'd expect, because you already have failures which you think are p < 1 (possibly p << 1) but are actually p = 1. In the case of the Gimli glider, they had two independent FQIS systems and a floatstick in case of a single failure, and a rule that the airplane was non-servicable in case of both failing. On the flight in question, one FQIS was non-servicable. The second was servicable but had been switched off, but due to a miscommunication it was thought that the no-fly rule had been overridden and the plane was OK with a floatstick measurement. Further, if the fuel calulation from the floatstick measurement had been correct, they would have refueled the plane and no-one would ever have heard about Air Canada Flight 143 because everything would have been fine. The problem was that they were knowingly operating in a failure mode, without either FQIS and disregarding the no-fly rule, and thinking that the floatstick measurement was sufficient. Therefore it only needed one further failure - miscalculating the amount of fuel from the floatstick - to bring about disaster.
chasing 13y ago
Is there a "news" element to this link (since the name of this site is "Hacker News")? Otherwise, it's an interesting story and it makes a good lesson, but I've been hearing it, now, for almost twenty years...
- scott_s 13y ago
  From the guidelines (http://ycombinator.com/newsguidelines.html http://ycombinator.com/newsguidelines.html): On-Topic: Anything that good hackers would find interesting. That includes more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity. Also, Please don't submit comments complaining that a submission is inappropriate for the site. If you think something is spam or offtopic, flag it by going to its page and clicking on the "flag" link. (Not all users will see this; there is a karma threshold.) If you flag something, please don't also comment that you did.
yurisagalov 13y ago
A similarly interesting incident happened with another Canadian airline -- Air Transat Flight 236[1]. [1] http://en.wikipedia.org/wiki/Air_Transat_Flight_236 http://en.wikipedia.org/wiki/Air_Transat_Flight_236
- refurb 13y ago
  Transat 236 is an amazing story. How lucky were they to run out of fuel, out in the middle of the Atlantic, but be able to glide to the Canary Islands? If it had had a few hundred pounds less of fuel, it would have ditched in the middle of the ocean and likely many of the passengers would have died.
  - brc 13y ago
    Azores. They are on the mid-atlantic ridge. The Canaries are off the coast of Africa.
    - refurb 13y ago
      Thanks for correcting me! I thought the Canary Islands didn't sound quite right.
- hanswang2013 13y ago
  Not only similar, Gimli Glider was glided 50 kilometres for about 17 mins. But Air Transat FLight 236 was glided 120 kms for 20 mins, which is the world record for gliding in Civil aviation.
rcthompson 13y ago
Nice of the airline to find the pilots at fault.
- lutorm 13y ago
  It is the pilot's responsibility to ensure that there is enough fuel for the flight, so that's no big surprise, especially since the fuel gauges were inoperative and they did not attempt to verify fuel level any other way. They weren't the only ones at fault, though.
  - sejje 13y ago
    Bullshit, the article clearly states they attempted to verify it with dipstick measurements and (faulty) math/conversions. In fact, they did that twice, before initial takeoff and after their first landing in Ottawa.
    - mikeash 13y ago
      That they attempted to verify and still came up with the wrong answer just reinforces their fault. They did a great job of handling the subsequent emergency, but I see no way around blaming them for it happening in the first place.
      - wdewind 13y ago
        The way around blaming them is that it has a horrible systemic effect to do so. In the future pilots are less likely to admit fault, less likely to provide details in investigations and so the organization has less data to learn with. Instead look at what happened and say "if things had been different this couldn't have happened" and then make those things a reality. Maybe the answer is putting a sticker with metric/imperial conversion on the tank or something, so pilots aren't confused when checking with dipstick.
        mikeash 13y ago
        I don't really follow. How are you going to recommend changes which help the pilots make correct decisions if you don't say that this event occurred because these pilots didn't make a correct decision?
grimmfang 13y ago
If any of you are really interested in these incidents they have recently been added to netflix titled "Air Disasters" and additionally you can find many more on Youtube from https://www.youtube.com/user/aircrashofficial https://www.youtube.com/user/aircrashofficial and similar uploaders!
mrbill 13y ago
"the cockpit warning system sounded again with the "all engines out" sound, a long "bong" that no one in the cockpit could recall having heard before and that was not covered in flight simulator training." I hope that's something that IS now covered. Why would you never train for that secenario?
- eskil 13y ago
  Did your drivers ed/school teach you how to drive with a hood that's flipped up at highway speed? Mine didn't, then it happened to me. (but yeah you're right)
  - adrianpike 13y ago
    Mine did, actually. My instructor used a clipboard to block my field of view, and walked me through coming to a controlled stop with minimal visibility.
    - ceejayoz 13y ago
      We didn't even cover highway driving in mine, let alone something like that.
      - gambiting 13y ago
        In Germany part of the training in many schools involves getting to the nearest autobahn and going at least 120mph to teach you driving at such speeds. Yes,there are training courses which don't do that, but it's not uncommon.
        fossuser 13y ago
        From what I've heard the driving/licensing test in Germany is actually a test - in the United States the written test questions show a picture of a stop sign and ask what it means (there are then three multiple choice options). The driving portion is not much more difficult.
8ig8 13y ago
As noted on "Some Famous Unit Conversion Errors" http://spacemath.gsfc.nasa.gov/weekly/6Page53.pdf http://spacemath.gsfc.nasa.gov/weekly/6Page53.pdf
sargun 13y ago
A great talk on failure: http://www.infoq.com/presentations/Debugging-Production-Systems http://www.infoq.com/presentations/Debugging-Production-Syst...
oscilloscope 13y ago
If you enjoyed this Wikipedia article and like video games, check out Kerbal Space Program. You'll be running out of fuel in no time.
- crystalmace 13y ago
  This is true.
reddit_clone 13y ago
There is an episode in the series 'Air Disasters' currently available in Netflix about this. Terrifying to say the least.
hyp0 13y ago
WTF/m theshold exceeded

176 points by lelf 13y ago

I was at that airfield last summer for a cadet course (I'm an air cadet) and I'll be going again this summer to get my glider pilot's licence; just like the pilot of the Gimli Glider did so many years ago! I can't wait!

techwatching 13y ago
Yay Manitoba! Winnipeg here.
- ahelwer 13y ago
  As long as we're sounding off, I grew up in Brandon. I'm over in Seattle now, though. What's the tech sector like in Winnipeg these days?
  - techwatching 13y ago
    Its low key. There's a very active design community, but comparatively limited startup activity.
efm 13y ago
The pilot (or co-pilot), I don't recall, was also an Air Cadet at that airfield, which is how he knew that it was there, a good long strip, and well maintained.
- crystalmace 13y ago
  Yes, and he was a glider pilot in the air cadet program which aided to his ability to properly land the plane without engines
  - seanmcdirmid 13y ago
    The pilot was a glider pilot, the first officer was an air cadet, and the field was already turned into a race track.

eddanger 13y ago

I hope the Americans don't use this as an excuse to stick with their old school system. I guess in one way they are closer to the Kingdom of England than us Canadians are.

johansch 13y ago
China uses metric. Just wait a decade or two...
- untothebreach 13y ago
  I really can't wait for us to start using a sane system. While we're at it, could we also start writing our dates in a sane way? Putting the month before the year is beyond ridiculous.
m_mueller 13y ago
After reading the whole article I'm convinced that learning metric from primary school age up would have avoided this accident. "In this case, the weight of a litre (known as "specific gravity") was 0.803 kg. (...) Between the ground crew and pilots, they arrived at an incorrect conversion factor of 1.77, the weight of a litre of fuel in pounds." See, here's where metric system sanity checks become relevant, that are simply not possible with imperial because nothing is compatible with each other. In metric, I just know, without any conversion factors to memorize, that 1kg water equals 1l at room temperature. Everyone with high school education should also know that gasoline products are lighter. Now I can do a sanity check - since the weight of one liter should be less than 1kg, there's no way 1.77 is right. If two well educated people do this math, at least one of them should see the mistake.
Patrick_Devine 13y ago
In the aviation world it's really mixed. ICAO uses imperial and metric measurements for different things. Feet are used for altitude and knots for distance, but temperature is always measured in centigrade. It's convenient to use feet because planes are stacked in 500' increments and not 152.4m increments. VFR (visual flight rules) flights are usually on the 500's (eg. 3500', 4500', etc. depending on heading) whereas IFR (instrument flight rules) flights are on the 000's (4000', 5000', etc.). Knots are convenient because 1 knot is equal to 1 minute of 1 degree of arc on a great circle. If you're flying anywhere far away this ends up being important as a great circle is the shortest route between any two places. Oddly enough, the metric system is useful with temperature because the standard lapse rate is 2 degrees per 1000' of altitude. So if you had to climb from 6000' to 8000' on an IFR flight plan, you would usually drop 4 degrees centigrade, which might be significant if it was raining out and it dropped below freezing. Having water on your wings and climbing up to an altitude where it's freezing is going to make you have a really bad day.

shruubi 13y ago

I'm guessing OP is a fan of Smodcast. http://smodcast.com/episodes/true-tales-of-canadian-heroism/ http://smodcast.com/episodes/true-tales-of-canadian-heroism/

bjg 13y ago

I'm curious if the submitter has been listening to SModcast[0]? They had a few episodes on the Gimli Glider recently. [0] http://smodcast.com/channels/smodcast http://smodcast.com/channels/smodcast

shadeless 13y ago

I heard about this recently on smodcast (podcast featuring Kevin Smith and his producer Scott Mosier), their reenactment was hilarious and I heartily recommend it - http://smodcast.com/episodes/true-tales-of-canadian-heroism/ http://smodcast.com/episodes/true-tales-of-canadian-heroism/

Karellen 13y ago

Ah yes, The Fundemental Failure Mode Theorem[0] at work: Complex systems usually operate in failure mode. Or, "That's why I'm skeptical of people who look at some catastrophic failure of a complex system and say, "Wow, the odds of this happening are astronomical. Five different safety systems had to fail simultaneously!" What they don't realize is that one or two of those systems are failing all the time, and it's up to the other three systems to prevent the failure from turning into a disaster." [1] [0] http://en.wikipedia.org/wiki/Systemantics#System_failure http://en.wikipedia.org/wiki/Systemantics#System_failure [1] http://blogs.msdn.com/b/oldnewthing/archive/2008/04/16/8398400.aspx http://blogs.msdn.com/b/oldnewthing/archive/2008/04/16/83984...

arnorhs 13y ago
The more fundamental thing to think about is: - what are the total number of failures that can happen? - what is the probability of those failures occurring - how many sets of those can combine into a catastrophic failure? And then from those numbers you can derive the probability of a catastrophic failure occurring.
- Karellen 13y ago
  Yes, but the thing that the Fundamental Failure Mode Theorem tries to draw attention to is "what is the probability of those failures occurring". i.e. it's possible that some of those failures have already occurred, and you just haven't noticed because the redundant systems are being redundant and preventing the overall system from failing catastrophically. Or you have noticed, but think that the redundant systems are sufficient, not realising how much closer they bring you to a single point of failure. So the probability of your whole system failing are higher than you'd expect, because you already have failures which you think are p < 1 (possibly p << 1) but are actually p = 1. In the case of the Gimli glider, they had two independent FQIS systems and a floatstick in case of a single failure, and a rule that the airplane was non-servicable in case of both failing. On the flight in question, one FQIS was non-servicable. The second was servicable but had been switched off, but due to a miscommunication it was thought that the no-fly rule had been overridden and the plane was OK with a floatstick measurement. Further, if the fuel calulation from the floatstick measurement had been correct, they would have refueled the plane and no-one would ever have heard about Air Canada Flight 143 because everything would have been fine. The problem was that they were knowingly operating in a failure mode, without either FQIS and disregarding the no-fly rule, and thinking that the floatstick measurement was sufficient. Therefore it only needed one further failure - miscalculating the amount of fuel from the floatstick - to bring about disaster.

chasing 13y ago

Is there a "news" element to this link (since the name of this site is "Hacker News")? Otherwise, it's an interesting story and it makes a good lesson, but I've been hearing it, now, for almost twenty years...

scott_s 13y ago
From the guidelines (http://ycombinator.com/newsguidelines.html http://ycombinator.com/newsguidelines.html): On-Topic: Anything that good hackers would find interesting. That includes more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity. Also, Please don't submit comments complaining that a submission is inappropriate for the site. If you think something is spam or offtopic, flag it by going to its page and clicking on the "flag" link. (Not all users will see this; there is a karma threshold.) If you flag something, please don't also comment that you did.

yurisagalov 13y ago

A similarly interesting incident happened with another Canadian airline -- Air Transat Flight 236[1]. [1] http://en.wikipedia.org/wiki/Air_Transat_Flight_236 http://en.wikipedia.org/wiki/Air_Transat_Flight_236

refurb 13y ago
Transat 236 is an amazing story. How lucky were they to run out of fuel, out in the middle of the Atlantic, but be able to glide to the Canary Islands? If it had had a few hundred pounds less of fuel, it would have ditched in the middle of the ocean and likely many of the passengers would have died.
- brc 13y ago
  Azores. They are on the mid-atlantic ridge. The Canaries are off the coast of Africa.
  - refurb 13y ago
    Thanks for correcting me! I thought the Canary Islands didn't sound quite right.
hanswang2013 13y ago
Not only similar, Gimli Glider was glided 50 kilometres for about 17 mins. But Air Transat FLight 236 was glided 120 kms for 20 mins, which is the world record for gliding in Civil aviation.

rcthompson 13y ago

Nice of the airline to find the pilots at fault.

lutorm 13y ago
It is the pilot's responsibility to ensure that there is enough fuel for the flight, so that's no big surprise, especially since the fuel gauges were inoperative and they did not attempt to verify fuel level any other way. They weren't the only ones at fault, though.
- sejje 13y ago
  Bullshit, the article clearly states they attempted to verify it with dipstick measurements and (faulty) math/conversions. In fact, they did that twice, before initial takeoff and after their first landing in Ottawa.
  - mikeash 13y ago
    That they attempted to verify and still came up with the wrong answer just reinforces their fault. They did a great job of handling the subsequent emergency, but I see no way around blaming them for it happening in the first place.
    - wdewind 13y ago
      The way around blaming them is that it has a horrible systemic effect to do so. In the future pilots are less likely to admit fault, less likely to provide details in investigations and so the organization has less data to learn with. Instead look at what happened and say "if things had been different this couldn't have happened" and then make those things a reality. Maybe the answer is putting a sticker with metric/imperial conversion on the tank or something, so pilots aren't confused when checking with dipstick.
      - mikeash 13y ago
        I don't really follow. How are you going to recommend changes which help the pilots make correct decisions if you don't say that this event occurred because these pilots didn't make a correct decision?

grimmfang 13y ago

If any of you are really interested in these incidents they have recently been added to netflix titled "Air Disasters" and additionally you can find many more on Youtube from https://www.youtube.com/user/aircrashofficial https://www.youtube.com/user/aircrashofficial and similar uploaders!

mrbill 13y ago

"the cockpit warning system sounded again with the "all engines out" sound, a long "bong" that no one in the cockpit could recall having heard before and that was not covered in flight simulator training." I hope that's something that IS now covered. Why would you never train for that secenario?

eskil 13y ago
Did your drivers ed/school teach you how to drive with a hood that's flipped up at highway speed? Mine didn't, then it happened to me. (but yeah you're right)
- adrianpike 13y ago
  Mine did, actually. My instructor used a clipboard to block my field of view, and walked me through coming to a controlled stop with minimal visibility.
  - ceejayoz 13y ago
    We didn't even cover highway driving in mine, let alone something like that.
    - gambiting 13y ago
      In Germany part of the training in many schools involves getting to the nearest autobahn and going at least 120mph to teach you driving at such speeds. Yes,there are training courses which don't do that, but it's not uncommon.
      - fossuser 13y ago
        From what I've heard the driving/licensing test in Germany is actually a test - in the United States the written test questions show a picture of a stop sign and ask what it means (there are then three multiple choice options). The driving portion is not much more difficult.

8ig8 13y ago

As noted on "Some Famous Unit Conversion Errors" http://spacemath.gsfc.nasa.gov/weekly/6Page53.pdf http://spacemath.gsfc.nasa.gov/weekly/6Page53.pdf

sargun 13y ago

A great talk on failure: http://www.infoq.com/presentations/Debugging-Production-Systems http://www.infoq.com/presentations/Debugging-Production-Syst...

oscilloscope 13y ago

If you enjoyed this Wikipedia article and like video games, check out Kerbal Space Program. You'll be running out of fuel in no time.

crystalmace 13y ago
This is true.

reddit_clone 13y ago

There is an episode in the series 'Air Disasters' currently available in Netflix about this. Terrifying to say the least.

hyp0 13y ago

WTF/m theshold exceeded