snow coming from Sweden I have learned to love it but in the world of Aviation it rarely brings good news that's certainly true for these pilots who are looking out through their cockpit Windows trying to make out the shape and position of the faint approach lights in front of them but when they finally realized the position they're in it comes as a real shock how is this possible stay tuned in the evening of the 29th of March 2015 an Air Canada crew was busy preparing to fly a standard passenger flight from Toronto Lester B Pearson International Airport up towards Halifax Stanfield airport in Nova Scotia Canada since it was March it was still winter in Northern Canada and that was most definitely true at their destination as the pilots were looking through the weather forecasts and observations they could clearly see that the weather in Halifax was far from ideal the latest metrological Aerodrome reporter matar indicated a win from 360 degrees at 19 knots gusting up to 26 in light and drifting snow giving a visibility of 1. 5 statute miles or 2400 meters with an overcast Cloud layer at 700 feet the temperature was -4 with a dew point of -5 and an air pressure of 29. 6 inches of mercury wasn't great but the real problem could be seen in the forecast for the time that there would be landing the snowfall was forecasted to increase in intensity to moderate and that would cause a reduction of the visibility to three quarters of a statute mile or 1 200 meters which would be very close to the minimum visibility that the pilots could accept for starting their approach they checked their approach plates and saw that with the type of wind that they would be facing they would most likely need to land on Runway 05 which was not equipped with a position of instrument Landing system because the 24 year old Airbus A320 that they would be flying wasn't equipped to fly a vertically guided ornam approach they would have to fly a localizer DME approach instead that's a type of approach which gets its horizontal guidance from a localizer antenna telling the pilots how to fly left and right just like an ILS approach does but it lacks the vertical Glide slope guidance and it's therefore considered a non-precision approach because of that the visibility requirement for flying this type of approach was higher and that was also the case for the minimum descent altitude the lowest altitude which the aircraft could descend to without having visual contact with the runway and still be able to land the approach plate for the localizer DME indicated a minimum visibility of one statute mile or 169 meters but because the crew and Air Canada had fulfilled certain training and Equipment requirements they had received a special approval to start this type of approach with half the published minimum visibility in this case half a statute mile this was important from a planning point of view but in reality the pilots would still have to properly see the runway and approach light when they reached that minimum descent altitude in order to land just like everyone else would at the time of planning the worst possible forecasted weather was still better than the minimum and the weather at our alternates was considerably better so the pilots concluded that they would likely be able to get down at the destination and if not well then they could just easily divert to be sure though they decided to uplift enough fuel to be able to hold for a considerable while in case the weather would actually be worse once a cabin crew had been properly briefed they all proceeded out to the aircraft and started preparing it for departure the aircraft was a 24 year old Airbus A320 which had flown just over 75 000 hours at the time of the flight it was equipped with two cfm-56 turbofile engines and was in good condition the only minor snag that the captain found when he was looking through the logbook was an inoperative number two air Pack Flow indicator which had been deferred to be fixed later and in accordance with the minimum equipment list but that wouldn't have any impact on their operation now the only real downside with this aircraft was like I mentioned before that it wasn't equipped for ornav approaches which would have made the lives of the pilots much easier at the destination but there wasn't much that they could do about that at this point given the poor conditions and relatively strong crosswind at their destination the captain decided to be Pilot Flying for the flight he was very experienced with about 11 700 hours of Total time 5575 of which have been flown on the Airbus A320 but he had only been flying as a captain for just over 1 200 hours he had been working for Air Canada over nine years at the time of the flight and he was accompanied in the cockpit by an almost equally experienced colleague the first officer had been working for the company over 15 years and had 11 300 hours of Total time he had actually accumulated even more time on the Airbus A320 than the captain had with a total type experience of almost 6400 hours so these were two very experienced pilots and it's likely that they felt quite comfortable in each other's company even though this was the very first time that they were working together as the captain was going through the pre-flight preparation the three cabin crew members were boarding the 133 passengers for the flight and helping them find their ways to their seats now if you think that it sounds a bit strange that there were only three cabin crew you're correct it's normally at least four in an Airbus A320 but Air Canada had recently been approved to operate with one cabin crew per 50 installed seats and this aircraft had only 147 seats this also meant that the cabin crew would have to open more than one emergency exit each in case of an emergency which required special training but this one to 50 rule had been approved before all cabin crew had received this training meaning that none of the cabin crew on board this flight had gone through this extra course when it came to the passengers were traveling this evening some of them were surprisingly lightly dressed boarding the aircraft in shorts skirts and t-shirts even though they were going up to Nova Scotia but I guess that Canadians are similar to swedes in this regard even a flashlight is seen as a sign of spring in March it is worth noting here that airlines flying in these type of conditions actually do issue guidance on what's appropriate to wear when traveling based on the season this guidance normally include wearing warm clothes as well as shoes whilst the aircraft is moving since in the unlikely case of an evacuation it might be needed after the boarding was completed the cabin crew proceeded with their standard emergency briefing they pointed out where the four cabin doors and the four overwing exit were and how to operate them if the command to evacuate would be given they also explained that in case an evacuation would be needed the passengers should leave all cabin luggage behind and move towards the closest exit following the emergency lighting in both the floor and the ceiling a mother who was traveling with her newborn baby was given instructions on how to hold the baby during takeoff and landing and also how to adopt the brace position if it should be needed but the infant was not given any seat belt as this was not required at the time on top of this the passengers were also shown how to use their oxygen masks and life vests as well as to please review the in-flight safety card in the seat pockets in front of them before departure now how many of you guys recognize this type of briefing I will guess quite a few of you but how many of you have actually taken two minutes away from Netflix and really thought through what this information means and how you should react if the this is an emergency Evacuate the aircraft using all available exit call is heard that's likely less of you but I strongly advise you to take those two minutes every time that you're traveling once the boarding was complete the cabin supervisor let the captain know that the doors were closed and ready for departure the pilots finished up their departure preparation and then requested pushback and start at time 2205 Air Canada flight 624 took off from Leicester B Pearson International Airport and started its flight up towards the North East they initially followed the dead key 3 departure route and continued climbing up to their planned Cruise altitude of 35 000 feet now due to Canadian legislation we don't know exactly what was said in the cockpit throughout this flight the exact cockpit voice recording transcripts are kept confidential in Canadian report but the reports do include what the pilots were discussing if that was deemed relevant to the outcome and because of this we know that the two pilots started discussing what alternate airport to use already during the climb out from Toronto this is a sign that they were likely quite apprehensive about the weather and knew that it could become a problem the captain suggested that they should change the active alternates from Montreal which they had filed in the flight plan to Moncton instead which was closer and could therefore enable them to hold for longer if the weather was below minimums when they arrived here it's probably worth explaining a few things about how we Pilots deal with poor weather especially poor visibility we have very specific minimum visibility values that we are allowed to operate in those values are even more restrictive during the planning stage when the aircraft hasn't yet departed especially for the alternate airport but even when we're Airborne we won't start an approach or try if the visibility is reported to be below minimum approved values which in this case was half a statute mile if the visibility does improve above that value we know that there is a mathematically High likelihood that we will be able to see enough to safely land when we reach our minimums so we will start the approach if that is the case but of course there's always a possibility that the actual visibility is way worse when we get down there so we might end up not seeing anything but in that case we would just execute a missed approach and climb back up again and then evaluate if we should make another approach or if we should just divert to our alternates following these rules are generally exceedingly safe and since we will never depart unless the weather at our alternates are significantly better than our destination under these type of circumstances we will always be able to land somewhere but but as always where the potential problem arises is where there is some ambiguities like for example how much visual references are enough to safely continue the approach below the minimums in the case of Air Canada that had been defined in their operations manual are seeing one of the following things either the runway or Runway markings the runway threshold or threshold markings the touchdown zone or Zone markings the approach lights the porp is the runway identification lights the threshold and Runway end lights the touchdown Zone lights the parallel Runway Edge lights or the center line lights this basically means that an approach could be continued providing any lights or markings associated with The Landing Runway could be seen at minimums but in reality it is quite a bit more complicated than that especially when you're flying a non-precision approach without vertical guidance that's because the visual picture that the Pilot's flying attains when going visual must be good enough to continue providing guidance on how to maneuver the aircraft visually below the minimums a good example is that if you're going Visual and all you can see is one or maybe two lights it is really hard to use those in order to tell you if you're drifting left or right and especially if you're going high or low in order to do that you often need several parts of the approach lighting system together with the runway lights to judge directional change the aspect ratio and so on this is why most modern approach light system includes several parallel barrettes giving additional visual guidance to the pilot even before the runway comes into sight the problem here was that the Air Canada operations manual had not defined that the pilots needed enough visual references to give this crucial Guidance the manual just stated that they needed at least one of those references to the inside in order to continue and this will become important soon the pilots continue to review the latest weather and no thumbs as the flight progressed up towards Nova Scotia they knew that Halifax Airport had four different runways all with Arnav approaches but like I mentioned before the aircraft wasn't equipped to fly those the main Runway 0523 was also the longest measuring 10 500 feet or 3200 meters and it had a category 2 ILS Precision approach available for rombo 2 3 but only a localizer or NDB non-precision approach for Runway 05 the other shorter Runway was disregarded due to the crosswind components and since the wind was mainly coming from the north the crew was left with only Runway 05 and its localizer approach there were also some other issues with using this Runway and I will explain that further after this let me tell you a bit of a story about two months ago I decided to go on a really delayed honeymoon together with my beautiful wife Sandra we decided to go to thailandis which is a country that we both love for the culture the food the people the weather well basically everything once we were there we were chilling in the hotel room one evening and I remember this classic Swedish TV series called 30 degrees in February which is about a bunch of lonely swedes who are moving to Thailand in Pursuit of Happiness it's a very sad and beautiful story and I wanted to show that to Sandra while we were actually there in Thailand but when I signed into assetia play it was of course yellow restricted to Sweden only and this happens all the time when I'm traveling nowadays so I downloaded nordvpn today's sponsor and then logged in clicked Sweden and voila we could start watching it immediately I actually use nor this way a lot when I'm out traveling both to see my own normal content but also to find better prices on tickets and hotels you should try it out you'll be amazed about the price differences obviously it's also a super fast VPN and it offers loads of safety features but my point here is that I really do use this service and that's why I have agreed to promote them so if you want to try out Nord then use the link here in the description below which is nordvpn.
com pilot to get four extra months for free when you sign a two-year deal it's a Time limited offer so click on it fast thank you note now back to the story not only did runway05 only offer a non-precision approach it also featured a quite basic approach light system called udal or omnidirectional approach lights this system consisted of five individual lights based 300 feet apart and therefore did not feature those barrettes that I talked about earlier that more advanced approach light systems did the runway itself was equipped with high intensity lights and a poppy which was set to indicate a Three Degree Glide slope now the way that the lighting system worked was that it could be set to five different intensities based on the visibility and Pilot's requests five was the highest setting for the runway lights giving 100 intensity and three was Max for the old dolls setting 4 was 25 intensity meaning that it was four times less bright than setting 5. that might sound a bit strange but the truth is that 100 brightness is very very bright and it can often be blinding for the pilots when they break through the clouds so 25 is often a much more appropriate setting to have one peculiarity here though is that the lights were controlled from the Tower and the setting was combined between the runway lights and the older so that when the visibility was less than half a statute mile at night the runway lights should be set to four and the all dolls should then be set to 3 which was Max for them but in Halifax a mistake to the setup of the lighting panel had been made at some point meaning that when the runway lights were set to four the ODOT would be reduced to setting 2 which meant a more than three times reduction in the intensity for the approach lights the touchdown so on the runway05 was also slightly uphill and that can in low visibility conditions give a visual illusion of the aircraft being slightly high which can then cause the pilots to pitch down the pilots of flight 624 knew that this was a potentially challenging approach especially with the kind of strong winds and snowfall that was forecasted so they started preparing early for the approach when flying into airports during the winter with low temperatures there are several Corrections that the pilots need to make in order for the aircraft to fly accurately and safely cool there will take up less volume than warm air and this means that minimum altitudes which the aircraft needs to follow during an approach needs to be corrected upwards to make sure that the correct terrain clearance is maintained that's because those shorted altitudes were calculated using something called standard atmosphere with a temperature of 15 degrees Celsius all altitudes below the corrected minimum sector altitude or the MSA needs to be corrected and Pilots use temperature tables to calculate how much each altitude needs to be changed and then they will enter that if needed into the flight management computer in this case the pilots corrected the Final Approach fix from 2000 feet to 2200 feet and their Minima or their MDA from 740 feet with a correction of 23 feet for temperature and then a standard additive of 50 feet from the procedures to a final value of 813 feet these Corrections were all done correctly and so were the FMC entries it was all handled professionally and diligently now since the starting altitude at the Final Approach fix had been changed the crew now also needed to change the flight path angle which they would need to fly during the approach down towards the runway the flight path angle from the approach plate was 3. 08 degrees and the pilots used another table to update this to 3.
5 degrees which was the value that the autopilot would then follow later on but how exactly was this approach supposed to be flown done well in the Airbus a localizer approach like this was supposed to be flown in a way referred to as coupled selected meaning that the autopilot was going to be used and coupled to the localizer beam for the lateral guidance and using a constant selected vertical descent angle from the flight control unit this is quite similar to the way that we fly a vertical speed non-precision approach in the Boeing but the flight path angle selection on the Airbus is supposed to be more accurate and constantly maintain whatever angle that the pilots have selected in theory if the descent is started at the correct point the corrected descent angle should put the aircraft in the correct geographical position when reaching the MDA and the pilot should then disconnect the autopilot and continue flying visually as the flight was now getting closer to the top of the sand the pilots received some updated weather for Halifax from their dispatch the situation had unfortunately worsened considerably with heavy and blowing snowfall and a visibility of only one quarter of a statute mile or 400 meters which was obviously not enough for them to start their approach but this patch also advised them that another Air Canada flight had successfully managed to land the runway05 having gone around on their first attempt due to poor visibility this information caused the pilots to continue to take more weather information for their alternates as well as verifying that the runway conditions were actually good enough to land which they were the runway was actually being continuously cleared they also carefully reviewed the Goron procedure to make sure that they were fully ready to execute that since the weather certainly indicated that it could happen if they even got to start the approach all in all the pilots of their slides were up until this point acting like real professionals and were discussing their arrival in a very cautious and conservative way when they saw that the weather wasn't good enough they calculated their maximum holding time decided to ask air traffic control to enter a hold if the weather was still bad when they got closer and they also decided on a time a specific time to start diverting if they couldn't get in just like basically like I would have done it at time 23 and 19 minutes the crew was clear to start descending down towards Halifax and two minutes later they finished their approach briefing they switched over to the Halifax terminal controller and asked if they could enter holding over an ornament Point called seti which they were clear to do and then they sent to 9000 feet the crew calculated that in the worst case scenario they would be able to stay in the hall for around one and a half hours until time sir 100. they were sitting in the holding the first officer got into contact with the Halifax Tower controller to get more accurate updates on the weather the tower controller told him that the visibility was still one quarter of a mile and that there were Vehicles removing snow on the runway at present as the aircraft continued descending in the hole the crew now started completing the in-range checks meaning among other things switching The Landing lights on as the first officers were doing this the captain told him that he would be keeping the lights off for the actual approach well this is quite often done in these type of conditions when the lights would only really illuminate the snow in front of the windscreen and not actually help in establishing visual contact the lights would then be switched on during the final part of the approach once contact had been established to assist with the landing the cabin crew completed their approach PA making sure that the cabin was Secure and that all hand luggage was properly stowed once this was done they gave the cabin secure assigned to the pilots seven minutes past midnight the captain said as they were still sitting in the hole that if the weather hadn't improved within the coming 20 minutes they would just divert now they had fuel to stay longer than that but if there's no positive tendency in the weather it might be better to just divert instead of burning fuel for no reason and on top of that the weather was actually getting worse with a visibility of only 1 8 of a mile with heavy snow and a vertical visibility of only 300 feet but four minutes later the controller came back and reported that the visibility had now started improving and it was close to half a mile and at times 16 minutes past midnight an official special weather report updated the visibility to half a mile enabling the crew to start the approach the terminal controller now cleared our Canada flight 624 to proceed to watch a point called oddcast which was on a 12 nautical mile Final Approach to Runway set of five and he also told them to start descending to four thousand feet a few minutes later they were cleared for the localizer approach and were told that the weather and Runway conditions were stable and wasn't changing much but it was still snowing the first officer selected The Landing lights off just like the captain had told him and as they were getting closer the aircraft leveled off at an altitude of 3400 feet once they were level the captain armed the localizer mode and asked for flaps one to be selected followed by flaps 2 and he then continued to descend down to watch 2 200 feet which was the initial approach altitude the aircraft intercepted the localizer and started turning towards the Final Approach track and as it was doing so both Pilots could see lights and the terrain below them which was a very good sign then probably quite encouraging but it doesn't necessarily mean that you will be able to see the runway through the slanting angle that they were approaching with the first officer who was now in contact with the tower controller asked him to please confirm that the lights had been selected to setting 5 or Max the tower controller who was still dealing with snow clearing equipment on the runway as well as with some other traffic at this point responded that the lights were at setting 4 but that they would move set to setting 5 later on as the aircraft paused about eight nautical miles at the time zero zero two six the captain called for the landing gear to be extended and for the landing checklist to be completed to the flaps this was done and as the aircraft leveled off at 2 200 feet the captain then continued to ask for flaps 3 and finally flaps full they were now fully configured for the landing and the only thing left to do was to initiate the final descent 2. 7 miles before the Final Approach fixed the captain activated the flight path angle mode and set an angle of zero degrees maintaining the altitude then as the aircraft Port 0.
3 nautical miles prior to the fav he selected The Descent of 3. 5 degrees and the aircraft started pitching down to follow this new command all according to Air Canada's Sops so far the aircraft was exactly where it was supposed to be fully configured and fully stabilized according to the Air Canada procedures and training at the time once the flight path angle had been selected the aircraft would just follow this angle and there was no further need to monitor that the aircraft was actually descending according to the profile the approach plates did include altitude checks to be done at given distances but those did not form part of the Air Canada approach procedure at the time even though airbus's own procedures did the reason Airbus recommended checking the altitude regularly during the final descent was that even though the autopilot would maintain a constant descent angle disturbances like a sudden gust of headwind for example could temporarily displace the aircraft From the Path then when the flight path angle was resumed it would no longer be on the same correct path that it was supposed to be and that was now exactly what was happening to flight 624 as they descended down they were hit with several strong gusts of wins and every time that that happened the aircraft would drift further below its intended path at time 0 0 2 9 and 27 seconds a radio altimeter call out of 400 was heard in the cockpit and this was almost immediately followed by the first officer calling out minimums lights only as they reach the minimum approach altitude the captain looked up and likely saw a few approach lights and then called out Landing at this point he should have also disconnected the autopilot and started flying the aircraft manually but instead the autopilot was kept engaged which meant that it kept descending at the same rate of around 700 to 800 feet per minute the problem was that the aircraft was about 0. 3 nautical miles further away from the runway than it should be at this point making it critically low but it was still close enough to the runway for the egpws system to not be activated during the next few seconds the pilots could be heard discussing and confirming that they could indeed see the approach lights they were about 0.
7 nautical miles or 1 300 meters away from the runway at this point and just overflying a lighted facility on the approach path at time 0 0 29 and 47 seconds The Landing lights were selected on followed almost immediately by the captain disconnect in the autopilot as the aircraft called out 100 and then 50.
