The Gimli Glider! Explained

an Air Canada Boeing 767 cruises along nicely at 41,000 ft when suddenly and out of nowhere they run out of fuel now how is the flight crew going to get this aircraft safely down on the ground and what led up to this this is the fascinating story of the gimly glider one of my all-time favorite avigation incident and accident story so make sure you stay tuned [Music] this video is brought to you together with skillshare now I know that you just like me are lifelong Learners that you're curious and you want to try to find new sources of information skillshare is a great tool for this they are an online learning platform with thousands of high quality video courses in pretty much anything that you can imagine now I've use it myself to try to improve my delivery to you you know uh there's a great course with sell Amore which tells you exactly how to do that but there's loads of other courses as well like professional photography for example or how you can use your own simulator to prepare yourself for your PPL license if you're interested in that the 1,000 first of you who uses this link here below will get a free trial of skillshare and if you find that you like it which I'm sure you will you can sign up and it's very affordable able it's less than $10 per month so sign up start learning today okay guys so today we're going to be talking about the gimly glider and like I said in the beginning of this video this is one of my alltime favorite stories because it has so many different components to it now as always when I'm talking about incidents and accidents I'm basing this on the final report and all of my sources that I've been using you can find in the description of the video if you want to read them through yourself but in order to understand how these guys could run out of fuel at 41,000 ft we have to go back a little bit in time and we have to look at the Boeing 767 that was involved in this flight so the 767 when this happened this was in uh July the 23rd of July 1983 was a fairly new type for Air Canada okay and so something that's going to become really important to this story is the fact that Canada as a country had decided to go over from the imperial units to the metric system now the 767 was the first aircraft in the Air Canada Fleet that used kilograms on their fuel gauges all right before that everything had been in pounds now this was obviously communicated there was some training material but there was still a little bit of uneasiness amongst flight crew about how to do these kind of conversions however it wasn't really an issue because you had your flight plan the flight plan was in kilos and then you can just compare what you had in kilos towards what you had on your fuel gauges and that was fine right now this particular aircraft um had had some issues with its fuel gauges before and on the night before the accident flight on the 22nd of July 1983 the on duty engineer came on board a flight Tech to find that the fuel gauges was blank all right they did not work but he had seen this before and he knew that there were two input channels to the fuel gauges so there are two independent channels that verifies how much fuel there is in the tanks there's a center tank and there are two main tanks in the wings and those two channels send their information to the gauges now it turns out that if those two signals are different or one is not working then the whole system blanks right stops working the engineer knew that if he could find the faulty signal and isolate that then the system would work again so he started checking it he found out that it was the uh second channel that wasn't working so he disconnected the second Channel he pulled the circuit breaker and he put a little yellow color on it to to show that this had been done when he did that the fuel gauges came back on the system is operational right how however if you've been following my podcast you know that when we talk about critical systems in the airline industry there has to be what we call redundancy that means that it cannot be just one critical system relying on one source so if you have this kind of problem where the two channels one was faulty and only one was providing information then that needs to be verified so the procedure is that you now need to do something called a drop stick test that is basically that in the wings and under the central tank there are these sticks okay that are connected to floats inside of the tank and if you turn them around and open them they fall down and they show how many centimet of fuel there is at that particular station in the tank now you have several of these drip sticks on each wing and when you do a drip stick test which takes a fair while it takes a good maybe 45 minutes to an hour to do then you see all right I have this many centimeters on these stations out on the tanks you take that into a manual and you check and that will give you the amount of fuel you have in the tank all right so the engineers did this check and they could quickly verify that what was on the fuel gauges in the cockpit corresponded to what was in the tanks according to the drip TS now taking over the aircraft on the accident day um was a captain called verer all right Captain ver was briefed by the uh Engineers that they had this issue uh but in the briefing he misunderstood it he thought that the aircraft had come in with this failure from a previous flight right he didn't understand that he was the first captain that was actually flying with this failure didn't really matter um they decided on how much fuel they needed to take up they verified how much fuel they had in the tanks and then they calculate how much more fuel they would need to uplift and then they verified the actual amount of fuel after the uplift using the drip stick procedure right this was all good the flight then pushed back it flew a two-leg flight from Edmonton to otava and then into Montreal and in Montreal there was a scheduled crew change right so during that crew change Captain ver met up with the next Captain that's going to take over the flight and this is Captain Pearson right and they talked a little bit on the on the parking lot and Captain V told Captain Pearson that they've had an issue with the fuel indicating system right and that there was a drip stick procedure needed this is something that happens very rarely so they would have had a bit of a discussion about it now the issue here and what seems to have been the issue here is that Captain Pearson misunderstood Captain verer Captain Pearson thought that the failure was a complete failure of the indication system okay that the indicators was blank and because of that you needed to do a drip sck test all right so this is what he understood unbeknownst to these two captains while they were out there talking another engineer has now entered into the cockpit of the 767 in question now this engineer is looking through the tech log and he sees the tech log entry from the previous engineer and he doesn't really understand it so he decide that he wants to do his own check of the system so he proceeds by pushing in the circuit breaker when he does so indication blanks again and then he does something called a bite test which is builtin test equipment and you have bite test for several systems it's a computer test that runs a self test on the system and this came out as failed right this is what he expected as well so he decides that he did he doesn't really like this okay he thinks that the second channel should be changed so he calls up the maintenance control center and asks to get a spare to to change the system it turns out that there's no spares for this particular problem they're going to have to wait until they're back again in Edmonton for the Knight change in order to find the spare and to change the channel now well he's talking to mol here he gets a second call and that's from the fueler the fueler needs help to do the drip test because you need an engineer to do that and here is where the next issue happens right because he now forgets to pull out the circuit breaker again that would have if it would have done that that would have reset the system and the fuel gauges would come back but the fuel gauges stay completely hidden okay so as the engineer now goes out and start dealing with a drip test Captain Pearson comes into the cockpit and remember he has already had a misunderstanding here so he looks and he sees what he's expecting to see which is no fuel indication he looks at Tech log the tech log says that there are issues with the fuel indication system okay he looks at the circuit breaker and he sees the yellow color and he assumes that it has been pulled the problem is that the yellow color is there but the circuit breaker has been pushed back in again so you can see how his kind of confirmation biased his bias to how the situation should look is now affecting what he's actually seeing okay he takes up the Mel that's the minimum equipment list now that is a list that we use when something is broken Ono the aircraft because we have so much redundancy in all of the different systems it means that under certain circumstances certain things can be broken remember how I told you about the one channel being broken that they have to do a drip test test in order to get redundancy so he looks at the ML and he finds something curious namely the M states that you are allowed to fly with one out of the three indicators in operative okay so if you have two working fuel gauges and one is not working you're allowed to dispatch provided that you've done a drip test however it also clearly then shows that you're not allowed to dispatch if there is no fuel indication right this is forbidden now here is where um a bit of the the the kind of backstory of the 767 comes in because the 767 is a fairly new aircraft and the ml is constantly being Rewritten and rechanged okay and this has led to a feeling amongst the pilots that if there is an Mel restriction you can always contact main trol their maintenance Control Center and they have a more detailed Mel that they can go into and override the Mel that the pilots have now this is a faulty impression but it's still there anyway now in the in the interviews after the accident Captain Pearson says that he talked to some of the maintenance personnel there and they said that this rule had been overwritten all right that you could dispatch without working fuel gauges um none of the maintenance Personnel says that that conversation ever took place but nonetheless Captain Pearson is now looking at the ML and he knows that the previous air crew has flown with his failure right he doesn't understand that the previous air crew came in with a very different failure than what he is seeing right now so he he decides to override it right he decides that he has enough reason to believe that his aircraft is safe to fly without fuel indications providing that a proper drip test has been done this is a major mistake okay and a major break of rules should be said as well anyway um the drip test is being done and of course this aircraft came in with a certain amount of fuel in their tanks now they need a minimum of 22,300 kilos in order to do the return flight from Montreal VI OTA to Edmonton so they need to figure out how much fuel to uplift the fueler wants the quantity in liters so when the drip test come back um they go into the manual and they see that on board they have 7,682 lers but they now need to convert that into kilos because that's what the flight plan is in and here is where the next major mistake is made so to convert liters into pounds you have a conversion factor of 1.77 but to convert it from liters to kilos it is 0.803 so what they now continue to do is that take 7,682 time 1.77 that is 13597 kilos is what they think they have it's actually pound then they take the minimum fuel required for the flight which is 22,300 minus the 13597 which gives 873 kilos which is incorrect and they then decide to convert that into liters by dividing it with 1.77 so 873 divided 1.77 is 4,917 L they pass that on to the fueler the fuel says well why don't we just round that up to 5,000 L shall we okay they say better safe than story and they upload 5,000 L now what they should have done all right was that they should have taken the 7,682 L times 0.803 that gives 6,169 kilos this is the correct conversion then the minimum fuel to dispatch 22,300 minus this 6,169 gives 16,1 31 kilos needed right then converted those kilos over to liters 16,1 31 divided with 0.803 gives 20, 88 l so they should have taken 2088 they took 5,000 L and that's because they using the wrong conversion method but of course you know if this would have happened with the previous failure in they would have uplifted it they would have looked at the fuel gauges and they would have realized that we need 20,300 we have like 8,000 on board but since they couldn't see the gauges this was not done the aircraft boarded its passengers 61 passengers uh they took off from the initial flight then to from Montreal to otava uh in otava they did another drip test but still used the wrong conversion method and because they did that they still got the kind of wrong numbers up it just looks like yeah everything is fine this is exactly according to what we were expecting and then they took off toward Edmonton so the takeoff climbed out perfectly normal climbed up to 41,000 ft and after a while at about 8:00 local time the first indication that something is wrong is happening okay and that is that they get a indication of a low pressure on the leftand fuel system this worries them a bit okay because they know that they have an issue with the fuel indication so they decide to divert to vinp which is about 120 miles away they initiate the uh descend toward vinp the descend to 35,000 ft and during the descend they get the next indication of low pressure on the right hand side this is now very quickly followed by the engine failure on engine number one and engine number two no more engines so the aircraft is now completely dark all right there is a St by Electric System that will give them some very limited Stam by instruments their primary displays are not working um they don't have a vertical speed indicator and of course when you're gliding the aircraft you want to have a vertical speed indicator in order to calculate how far you can go first officer quintal sits and talks to our traffic control calls out the MayDay obviously communicates and asks them to give him a distance reading so he can calculate how much time is going by how much distance they're going and how much they're descending and from that they calculate that they have a glide ratio of about 1 to 12 so sitting at 35,000 ft it's about 65 miles to go to Winnipeg and it's about 45 miles to go to a little Airfield called gimle now they know about gimle because first off the quintal used to be in the Canadian Air Force and he was flying out of gimy but what they don't know is that gimy has been decommissioned right it's no longer an active base in fact the uh there is a a club a driving Club in Winnipeg who's using it to do drag races and on this day on the 23rd of July 1983 there is a big drag race taking place in gimy the they don't know about this it's a nice day they see the Airfield gimly quite far out and something that's also playing in their favor is that Captain Pearson is an accomplished glider pilot is very very skilled at gliding so this sitting and Flying Without engines it's not something that is completely new to him he has reduced the speed back of the aircraft to about 220 knots which he thinks is the best gliding speed more or less and he's now aiming towards gimy also something that's worth knowing here is that the 767 requires hydraulics in order to drive its flight controls all right it's not like the 737 which has some wires that goes out and you can actually fly it without Hydraulics no this is just two big Rudder surfaces so in order to provide electrical power to drive the hydraulics in a situation like this something called a ramare turbine has dropped out it's a little propeller that is providing uh electrical energy in order to to you know control the aircraft so they still have control of the aircraft they have limited instrumentation they talked to our traffic control they've sent on the information to the U cabin crew the cabin crew is now doing an amazing job in the back by informing the passengers about the potential emergency landing and also calming passengers down this is something they're going to be commended for later on anyway they're now descending down and they realized that from 35,000 ft if they flying 45 5 miles they're going to be quite high they discussed the possibility of maybe doing a 360 turn you know but they didn't know exactly how much altitude they would lose by that um and they didn't want to risk not being able to reach gimly so instead Captain Pearson takes out a little you know Knowledge from his gliding days and he says why don't we do a forward side slip a forward Sid slip is something you do on smaller Craft on Cessnas Pipers or gliders and what you do is you basically fly with opposite roders so in the case of Pearson sitting on the left side he would probably have pressed the right rodder in order to move the nose to the right and then put left Aon in in order to keep the track going so this way he can look out through his side window and see the um the airport and judge whether or not he is high or low now we don't do that on swep do larger Air transport airplanes and that's because there is going to be a lot of turbulence coming off the body and that turbulence can go into the engine and if you have two engines running that might actually cause the engine to stall and you could end up at a low speed situation with a suddenly stalling engine and that could get you into a really hard place when it comes to controlling the aircraft but also something that this crew has not thought about is the fact that when they go into a side slip the Airstream over the ram a turbine is also interrupted so the ram turbine does not get as enough air flow over it it slows down that means that they now have less hydraulic power available and they notice this when they try to straighten the aircraft out that it is much much harder to move and that's because of this anyway they now continue to watch the Airfield and they realize as well that they cannot get the flaps and the slats out because they require a fully working hydraulic system they don't have that so they're sitting at this around 200 knots which is very very high air speed they tried to extend the landing gear now the landing gear also requires Hydraulics to work um first off the quintal is trying to find the quick reference handbook um he cannot find the correct checklist so he just reaches over for the Emergency extension now I've done a video about how we do emergency extension in the 737 737 you basically have to open the door in the floor and Pull and kind of release the uplook for each of the landing gears it is a slightly different system on the 767 but it works essentially the Same by letting the gear gravity fall out into the aam now that works fine for the main landing gear but as the nose gear is extending it goes out but it doesn't lock in the position so the nose gear is now unsafe which is going to turn out to be actually a fairly good thing they're getting closer towards the runway and as they get closer to the runway they start realizing that there's loads of people here at the far end of the runway there's a drag race going on there's loads of people there and the issue here of course that without engines this aircraft is almost completely quiet no one hears this aircraft coming in okay the kids looks up and they see this enormous 767 barreling down on them and in the interviews afterwards the flight crew said that they were so close to these kids that they could see the terror in their faces the kids are okay though they land and as the nose gear touchdown because it's unsafe it just falls back in again the nose falls down and it starts grinding across the runway this provides a lot of braking for the aircraft uh the flight crew puts Max manual braking on but because there's no antis skid system working without the Hydraulics working what happens is that the gear just looks up and looking up at this speed it just means that they blow out instantly so now they have blown out tires and they're skidding down the runway towards the people at the far end um along the runway about halfway down or so there are these guard rails that have been put up to basically to you know keep the public from the racers and the flight crew managed to use a little bit of differential breaking to kind of push the aircraft up against one of these guard rails to get further deceleration from that and they manag to get the aircraft to a Full Stop gets quiet the aircraft has landed successfully okay no one is Hurt No One Is Dead the cin crew immediately begins an evacuation because the aircraft has been skidding across the the runway there's a little bit of smoke in the forward part of the aircraft so most of the passenger goes towards the back in the over Wings to try to get out now there's a little bit of an issue here because the nose obviously is sitting down on the runway which means that the back of the aircraft the emergency exits are are higher than normal so the emergency escape slides are basically hanging almost vertical and there are a few people who hurt themselves as they're basically jumping out on the very very steep uh Escape slides but all all in all this is an amazing outcome all right they have taken a situation that was potentially catastrophic and they've turned it into something that is semi good okay now the investigation into this revealed several things first of all the pilots were partially blamed for their inability to do the fuel conversion using the correct numbers but that was also put on the kind of shoulders of Air Canada because they hadn't properly trained the pilots they hadn't properly communicated these changes specifically with the changes in roles from a three pilot cockpit with a flight engineer to a two pilot cockpit and also the ongoing changes from a imperial to the metric system uh there was talks about the lack of U spares you know if they would have had spares available this fault with the fuel gauge would have been fixed already and this would not have been a factor uh and some other items as well the captain captain Pearson was demoted to First officer for six months and first officer quintal was actually uh suspended for two weeks and three of the maintenance Engineers that was involved in this was also suspended now the flight crew did an appeal to this and they managed to appeal it successfully they would put back into their flying positions and they continued to fly for many many years and in fact in 1985 first officer uh quintal and Captain Pearson was awarded the feder atic international diploma for outstanding airmanship for the very first time all right the first time that this diploma was given out it was given to this flight crew so they were considered Heroes now I'm guessing that you guys have some questions about this and maybe you have some suggestions about other incidents and accidents that I should be covering in this series if you do please go into the comment section below I love hearing from you I hope that I have earned a subscription from you if you like this kind of content make sure that you subscribe to the channel and that you've highlighted the notification Bell so you know when I'm doing things like you know spontaneous live videos and stuff if you want to talk directly to me or other Aviation enthusiasts then I highly recommend you to check out my Discord server right in the description of the video there's an invite to my Discord server where you can chat with other people about loads of different topics and you can share pictures and other cool stuff there's always something happening in the Discord server have an absolutely fantastic day wherever you are and I'll see you next time bye-bye all right guys I really hope that you likeed that if you want more content like that more Aviation content well then check this out uh I hope that you have subscribed to the channel and that you've highlighted little notification belt see you inside of the mentor Aviation app and have an absolutely fantastic day bye-bye oh [Applause] [Music]

Channel: Mentour Pilot

Views: 1,008,082

Keywords: Gimli Glider, Boeing 767, Fuel calculation error, Drip stick, Drop stick, Aviation incident, avaition accident, Air Canada, Air Canada flight 143, metric system, imperial system, Fear of flying, Fear of flying help, nervous passenger, nervous flyer, nervous flyer help, pilot life, aviation facts, Aviation explained, Dr Reason´s model, Swiss cheese model, Boeing 737, Boeing 787, Boeing 747, Airbus A380, Airbus A350, flying on empty, aircrash investigations

Id: cZkKFSqehN4

Length: 27min 34sec (1654 seconds)

Published: Fri Dec 11 2020