Air Canada A320 accident at Halifax
On page 2 of the report, it says that the cold weather correction to the MDA was 23 feet. This equals 8% of the difference between the MDA and the threshold elevation. So maybe the altimeter was set to the actual field pressure, and the cold weather correction at the threshold was zero?
Hi Slast,
Ref cold weather temperature corrections, you need to know that the definition of QNH (the altimeter setting in America and Canada). By definition there is no temperature error at airfield elevation, but an increasing one the higher above airfield elevation you get. Even in Denver if the OAT was -60 Celsius, your altimeter would read correctly at airfield elevation.
https://www.skybrary.aero/index.php/...ssure_Settings
Airfield QNH is obtained by correcting a measured QFE to sea level using ISA regardless of the temperature structure of the atmosphere. As your altimeter is calibrated using ISA, it will indicate altitude correctly at the airfield reference point. At other altitudes, the indicated altitude is likely to be in error, depending on the temperature of the atmosphere.
Ref cold weather temperature corrections, you need to know that the definition of QNH (the altimeter setting in America and Canada). By definition there is no temperature error at airfield elevation, but an increasing one the higher above airfield elevation you get. Even in Denver if the OAT was -60 Celsius, your altimeter would read correctly at airfield elevation.
https://www.skybrary.aero/index.php/...ssure_Settings
Airfield QNH is obtained by correcting a measured QFE to sea level using ISA regardless of the temperature structure of the atmosphere. As your altimeter is calibrated using ISA, it will indicate altitude correctly at the airfield reference point. At other altitudes, the indicated altitude is likely to be in error, depending on the temperature of the atmosphere.
Thanks LD
Thanks LD, I knew there had to be a flaw in my logic! Its a long time since I've had to think about how QNH is derived at cold/high airports. Senior moment etc....
Last edited by slast; 22nd May 2017 at 06:33.
There have been a number of accidents over the last few years where the autopilot has been used below minimums on a non precision approach. The Turkish airlines crash in Nepal is a classic example. If the pilots had been flying manually, they would probably have been forced to recognise sooner that they did not have enough visual reference to land safely. This is where the over reliance on automation bites. I fly quite a number of non precision approaches using vnav lnav and in good weather it can be startling how far off the papis and extended centreline the aircraft can be just above mdh. We get lulled into a false sense of security by the reliability of the autopilot. The only positive aspect seems to be that in the Air Canada and Turkish cases at least, the aircraft crashed onto the airfield with not too many casualties.
I heard the Head of TSB Canada speak at a conference last year. She commented that they were seeing an increasing incidence of ineffective regulatory activity in all domains, citing examples of deficiencies in an operator's management, training and SOPs where the regulator was aware but had failed to intervene.
She also said that SMS worked where there was an ability to identify problems, the capability to fix them, and the organisational commitment to do so, but that it all needed to be overlaid with balanced regulatory oversight.
It is always worth remembering that 'oversight' has two meanings: one refers to supervision, the other refers omission. Some NAAs appear to be elevating the latter concept to an art form.
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I fly quite a number of non precision approaches using vnav lnav and in good weather it can be startling how far off the papis and extended centreline the aircraft can be just above mdh.
Hopefully, when you say being far off of extended centerline, you mean vertically, not horizontally.
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If you just check the altitude vrs. DME, without temperature compensation, as a procedure, you could be really low; to check each fix could take 10-15 minutes in a holding pattern. TC probably said, "Why bother? Don't want that can of worms! Just let's not reference DME vrs. Altitude." Sam
But why would you not check the vertical profile whether required by SOPs or not.
Isn't there an element of self preservation in all of us pilots.
mcdhu
I'll admit to not having read the whole thread, or not yet the whole TSB report. For interest I'll be seeing an AC mate from B767 fleet and ask him about their type SOP's. But the above comment raises the question that is becoming more common; what should you do, from an airmanship point of view, outside SOP's? In today's diluted training environment it is a very disturbing discussion. I flew for an airline that included the SBY ILS in the approach checks. i.e. switch in ON. It was then removed from the checklist so some pilots then concluded it was no longer necessary to switch it on for approach. Trained Monkey stuff. Those of us of longer tooth decided that airmanship dictated it was still a good idea. Indeed we'd been doing it before it was ever on the checklist. It somehow became an adopted procedure and we never knew why it was removed. However, even some 'still quite raw' new generation LTC's suggested it was no longer necessary during Line Checks of some of us dinosaurs. That led to interesting debates along the lines of "show me where it says I MUST NOT switch it on."
In more general terms it does disturb me that many training dept's are generating type rated LST passing pilots and them grooming them into company SOP obedient a/c operators. There is less and less the creation of type rated airman who operate according to company SOP's. It did make me laugh at an airline who trumpeted that they had comprehensive ultra-safe well proven SOP's that were binding: they then also suggested that airmanship was an SOP, but there was considerable lack of evidence of that amongst new generation crews on the line. They were either ignorant of the concept or felt too inhibited to apply any discretion.
Apologies for thread creep. Much has been thrashed out previously, but this is not about manual skills, rather management & operational skills. Is it that SOP's are diluting self-preserving airmanship techniques?
But why would you not check the vertical profile whether required by SOPs or not.
Isn't there an element of self preservation in all of us pilots.
mcdhu
I'll admit to not having read the whole thread, or not yet the whole TSB report. For interest I'll be seeing an AC mate from B767 fleet and ask him about their type SOP's. But the above comment raises the question that is becoming more common; what should you do, from an airmanship point of view, outside SOP's? In today's diluted training environment it is a very disturbing discussion. I flew for an airline that included the SBY ILS in the approach checks. i.e. switch in ON. It was then removed from the checklist so some pilots then concluded it was no longer necessary to switch it on for approach. Trained Monkey stuff. Those of us of longer tooth decided that airmanship dictated it was still a good idea. Indeed we'd been doing it before it was ever on the checklist. It somehow became an adopted procedure and we never knew why it was removed. However, even some 'still quite raw' new generation LTC's suggested it was no longer necessary during Line Checks of some of us dinosaurs. That led to interesting debates along the lines of "show me where it says I MUST NOT switch it on."
In more general terms it does disturb me that many training dept's are generating type rated LST passing pilots and them grooming them into company SOP obedient a/c operators. There is less and less the creation of type rated airman who operate according to company SOP's. It did make me laugh at an airline who trumpeted that they had comprehensive ultra-safe well proven SOP's that were binding: they then also suggested that airmanship was an SOP, but there was considerable lack of evidence of that amongst new generation crews on the line. They were either ignorant of the concept or felt too inhibited to apply any discretion.
Apologies for thread creep. Much has been thrashed out previously, but this is not about manual skills, rather management & operational skills. Is it that SOP's are diluting self-preserving airmanship techniques?
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On first read a rather well prepared report with no window washing. What I find rather sobering is the number of uncovered shortcomings both on the side of the airport and the operator, many of which were not a contributing cause and would have remained unnoticed were not for the accident.
The crew set up an approach for some of the nastiest conditions imaginable. They hit the button at the FAF to have George drive all the way down to the ground on a calculated FPA. Georges let the airplane get low but nobody noticed because the SOP said they didn't have to check.
They let Georges continue way below minimum disconnect height, as they thought they might see something, they had a "conversation" about what they COULD see when well below MDA. Eventually they decided things weren't right, in just enough time to write the aircraft off without actually killing anyone. Since the minimum altitude shown is 50 ft below the threshold, it seems to have been only by a huge amount of luck that this wasn't 138 fatalities and not AC's initially claimed "hard landing"!
But hey, according to this report it was all in accordance with the local laws and the airline's own SOPs, so, no big deal! You don't need to see an actual timeline of crew or automatic callouts, or other flight parameters. The report provides over 20 paragraphs about the Captain's snoring/potential fatigue problem, which it turns out not to have been an issue, but only 2 about why the aircraft deviated from the planned flight path to cause the accident. It simply says "the wind did it".
But the Airbus explanation chart that says wind changes cause distinct individual variations before returning to parallel the initial path. The rather poor quality trace provided seems to show steadily increasing divergences all the way from the start.
Then there's a whole lot of stuff about the lights and what might theoretically have been visible in those conditions, but although they survived without major injuries, not a word about what the pilots recalled actually seeing.
Am I the only one wondering whether if this had been in Asia or some other regions, this report would have been greeted with a certain amount of derision by many ppruners??
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They were nasty conditions, and the crew was waiting to see what they wanted to see ...
Going below a published minimum without proper visual references.
Minimum that was already pretty low for the approach type in service and the added complexity of the temperature corrections and proper fix and distance confirmation through a remote DME.
A reminder for all of us.
Going below a published minimum without proper visual references.
Minimum that was already pretty low for the approach type in service and the added complexity of the temperature corrections and proper fix and distance confirmation through a remote DME.
A reminder for all of us.
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Is it strange to have power lines on the airport boundary?
Additionally it seems to be a pretty obvious failure mode to have a non-redundant power feed which your aircraft rely on, in a location where the same aircraft can damage the lines.
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Spoke to an AC buddy on a different type. They start descent in whatever mode and only check the 4nm v ALT, not all the DME's all the way down. He seemed to suggest that, after this event, the 'visual reference' had been modified and if 'lights' can be seen they can continue below DA on autopilot. Sadly our conversation was distracted and I never cleared up that point. Are there those in the know? It seemed in quite a few scenarios AC's procedures differ quite a bit from common EASA ones. It seems there is also a dodgy culture shift westwards.
Last edited by RAT 5; 10th Jul 2017 at 10:09.
The southern boundary of YMML doesn't have above ground power lines. And public lighting to the south and west of Essendon airport is a special type, with shorter, more closely spaced poles. Both locations seem to have given thought to the possibility of an aircraft coming in low.
Additionally it seems to be a pretty obvious failure mode to have a non-redundant power feed which your aircraft rely on, in a location where the same aircraft can damage the lines.
Additionally it seems to be a pretty obvious failure mode to have a non-redundant power feed which your aircraft rely on, in a location where the same aircraft can damage the lines.
In which case, the power lines are the least of your problems....
https://www.flightglobal.com/assets/...x?itemid=60703
In effect, these power lines are "buried" - about 5m below the tarmac elevation.
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Post on this, May 18th from ACPA
https://acpa.ca/newsroom/acpa-media-...-tsb-inve.aspx
https://acpa.ca/newsroom/acpa-media-...-tsb-inve.aspx
Last edited by Retired DC9 driver; 3rd Jul 2017 at 23:41.
Typical BS...
It's time AC joins the 21st century and equips its aircrafts with the proper equipment.
If a privately owned single engine aircraft can be equipped with WAAS/SBAS then surely a modern airliner like an Airbus 320 can be equipped with WAAS/SBAS.
Ground based nav aids are most likely going to be phased out at some point and satellite based approaches are going to become more and more the norm IMHO.
It's time AC joins the 21st century and equips its aircrafts with the proper equipment.
If a privately owned single engine aircraft can be equipped with WAAS/SBAS then surely a modern airliner like an Airbus 320 can be equipped with WAAS/SBAS.
Ground based nav aids are most likely going to be phased out at some point and satellite based approaches are going to become more and more the norm IMHO.
Meanwhile in the back, there were well over a hundred GPS units in smartphones.
Mind at our recent provincial glider contest, people's smartphones were a couple miles off. Can't always count on them.
The glider mounted GPS loggers worked just fine - for under $1000.
Mind at our recent provincial glider contest, people's smartphones were a couple miles off. Can't always count on them.
The glider mounted GPS loggers worked just fine - for under $1000.
Canadian Visual reference requirements and AC624 report
I am surprised there has been no comment about this aspect of the AC624 accident report. If you read it in detail, 138 people missed almost certain death by less than a second, and escaped only because by good luck that the runway is at the top of a slope. They were well below runway level for several seconds, and it just avoided being the worst civil air accident in Canadian history.
Pretty clearly, the immediate cause of the accident was continued descent below MDA without the pilot having enough visual cues to either reach the runway safely or determine that the aircraft was not properly placed to do so. But there's nothing in the analysis, causes or risk findings about the fact that apparently Canada does not adhere to ICAO standards regarding visual references.
Annex 6 etc is very simple: at DH/MDA the visual cues "should have been in view for sufficient time for the PILOT to HAVE MADE an assessment of the aircraft position and rate of change of position, in relation to the desired flight path". The assessment process ENDs when the aircraft reaches DH/MDA.
But the CAR visual reference requirement is different: ".... visual aids that, when viewed by the pilot of the aircraft, ENABLE THE PILOT to make an assessment of the aircraft position and rate of change of position, in order to continue the approach and complete a landing", and any one of the listed items will meet that requirement.
If you can START an assessment at DH/MDA, presumably it can have two possible conclusions - the flight path is satisfactory, or it is not. In the latter case, surely you have to go around - but by definition you are below the height at which a safe instrument go-around can be made.
From this report it not only seems entirely acceptable under CAR to have a decision process STARTING at the MDA, but in effect to have it made by committee of 2, and not just "the pilot" who will be doing the landing. The report consistently refers to "the flight crew" (both pilots) rather than the pilot (actually responsible for making the landing) making these assessments below MDA.
A short recap: at MDA, the F/O says he can see some lights. The Captain commits to landing and then STARTS making his own assessment. A debate occurs, with both talking about what they can see. The F/O becomes unhappy and calls for a go-around, with which the Captain subsequently concurs. The go-around starts from a height when the aircraft should be in the flare, only 15 feet above runway level, but is actually well short of the runway.
This seems to be in accordance with CARS and the conflict with Annex 6 doesn't get a mention in the report. The fact that AC did not include the words about assessing the flight path doesn't seem to materially affect the outcome - what else would you use the cues for? (Though this omission seems to be another item that had slipped through TC's supervision.)
The report also says AC has now removed the "lights only" call, which presumably leaves only ""no contact" or "runway in sight". Since typical DH/RVR ratios don't expect the runway to be in sight at DH, (e.g in Cat 1 at 200ft the aircraft is 3000 ft from the threshold with 550m/1800ft RVR), what does the PM now call if only approach lights are visible? "No contact" or "runway in sight"? Neither of which is true?
Pretty clearly, the immediate cause of the accident was continued descent below MDA without the pilot having enough visual cues to either reach the runway safely or determine that the aircraft was not properly placed to do so. But there's nothing in the analysis, causes or risk findings about the fact that apparently Canada does not adhere to ICAO standards regarding visual references.
Annex 6 etc is very simple: at DH/MDA the visual cues "should have been in view for sufficient time for the PILOT to HAVE MADE an assessment of the aircraft position and rate of change of position, in relation to the desired flight path". The assessment process ENDs when the aircraft reaches DH/MDA.
But the CAR visual reference requirement is different: ".... visual aids that, when viewed by the pilot of the aircraft, ENABLE THE PILOT to make an assessment of the aircraft position and rate of change of position, in order to continue the approach and complete a landing", and any one of the listed items will meet that requirement.
If you can START an assessment at DH/MDA, presumably it can have two possible conclusions - the flight path is satisfactory, or it is not. In the latter case, surely you have to go around - but by definition you are below the height at which a safe instrument go-around can be made.
From this report it not only seems entirely acceptable under CAR to have a decision process STARTING at the MDA, but in effect to have it made by committee of 2, and not just "the pilot" who will be doing the landing. The report consistently refers to "the flight crew" (both pilots) rather than the pilot (actually responsible for making the landing) making these assessments below MDA.
A short recap: at MDA, the F/O says he can see some lights. The Captain commits to landing and then STARTS making his own assessment. A debate occurs, with both talking about what they can see. The F/O becomes unhappy and calls for a go-around, with which the Captain subsequently concurs. The go-around starts from a height when the aircraft should be in the flare, only 15 feet above runway level, but is actually well short of the runway.
This seems to be in accordance with CARS and the conflict with Annex 6 doesn't get a mention in the report. The fact that AC did not include the words about assessing the flight path doesn't seem to materially affect the outcome - what else would you use the cues for? (Though this omission seems to be another item that had slipped through TC's supervision.)
The report also says AC has now removed the "lights only" call, which presumably leaves only ""no contact" or "runway in sight". Since typical DH/RVR ratios don't expect the runway to be in sight at DH, (e.g in Cat 1 at 200ft the aircraft is 3000 ft from the threshold with 550m/1800ft RVR), what does the PM now call if only approach lights are visible? "No contact" or "runway in sight"? Neither of which is true?
Last edited by slast; 8th Jul 2017 at 15:47. Reason: typo
Since typical DH/RVR ratios don't expect the runway to be in sight at DH, (e.g in Cat 1 at 200ft the aircraft is 3000 ft from the threshold with 550m/1800ft RVR), what does the PM now call if only approach lights are visible? "No contact" or "runway in sight"? Neither of which is true?
Capn Bloggs, you say "The call should be "Visual" " - my emphasis. Can you clarify for me whether this is an opinion or is it what the AC procedure wording says? Do you have the actual AC text that is associated with it ?
Thanks, Steve
Thanks, Steve
Slast, the apparent AC text is at the bottom pf page 44:
.
During a non-precision approach, when the aircraft reaches the MDA, a PM is required to make a call of “Minimums” followed by either “No contact,” “Lights only,”70 or “Runway in sight.” The response by a PF is to call either “Go-around, flaps” or “Landing.”
Air Canada does not provide any specific training on or definition of what “Lights only” entails.
When a PM calls, “Lights only,” a PF expects that the PM has acquired visual references in order to continue with the approach. The typical response is for the PF to call, “Landing,” and to continue with the approach.
Air Canada does not provide any specific training on or definition of what “Lights only” entails.
When a PM calls, “Lights only,” a PF expects that the PM has acquired visual references in order to continue with the approach. The typical response is for the PF to call, “Landing,” and to continue with the approach.