Air Canada A320 accident at Halifax

[Gilles Hudicourt]

Originally Posted by Retired DC9 driver

I find it hard to believe that Gilles would think none of this was done

I don't think anything, except that report glosses over a number of important and highly relevant things which should have been spelled out.

Here is an example of what I mean:

The cabin crew then made a passenger announcement, which included instructing passengers to stow their carry-on baggage, put their seat backs upright, and fasten their seat belts. The cabin crew subsequently confirmed that these actions had been taken.

I find it hard to believe the cabin crew would not have done these actions which they do during every flight. Yet it is mentioned in the report. It does NOT leave the reader to ASSUME they were done as they should have been.

Originally Posted by Retired DC9 driver

For a flight in FPA guidance mode, Air Canada’s practice was that, once the aircraft was past the FAF, the flight crews were not required to monitor the aircraft’s altitude and distance from the threshold, nor to make any adjustments to the FPA.

Which is one of the many contradictions of the report, for in the same report one can read:

The following Air Canada documents are available to flight crew:
• The TC-approved Aircraft Operating Manual (AOM), which contains the SOPs, is based on information about the operational, technical, procedural, and performance characteristics of the aircraft in the Air Canada Flight Crew Operating Manual (FCOM).
Flight crews use the AOM for all aircraft operations.
• The FOM contains information that applies to all flight operations, except when superseded by an AOM.
• The Flight Crew Training Manual (FCTM) is designed as a reference document to provide pilots with practical information on how to operate the Airbus aircraft.

The Air Canada FCTM indicates that the flight crew should monitor the aircraft’s position along the vertical flight path while conducting a non-precision approach, by referring to the distance indicated on the distance measuring equipment, the altimeter reading, and the time.

And the report (not me) later quotes the same Air Canada FOM:

No flight shall continue an approach past the FAF Arrival Gate unless it is being flown in a way that ensures the Stable Approach Criteria will be met by the 500 foot Arrival Gate.

At the second gate (500 feet AGL or 100 feet above the MDA), no flight shall continue unless the following stable approach criteria are met:
• Flaps and landing gear are in the landing configuration; and
• Landing Checklist completed; and
• Indicated airspeed with plus 10 knots to −5 knots of target airspeed (Airbus-target airspeed is Ground Speed Mini when active); and
• Thrust stabilized, usually above idle, to maintain the target approach speed along the desired flight path; and
• Established on the correct vertical approach path and where applicable, remaining within ½ scale deflection of the guidance used for an
instrument approach or, for a visual approach, established on the correct approach slope as indicated by visual approach slope indicators (i.e.
VASIS [visual approach slope indicator system], PAPI or HGS [head-up guidance system]); and
• Rate of descent not in excess of 1000 fpm unless required to maintain the published constant descent path (e.g. glideslope, VASIS, calculated
descent rates, etc.). If an approach requires a rate of descent greater than 1000 fpm, a special briefing should be conducted; and
• Established on the correct lateral approach path and where applicable, remaining within ½ scale deflection of course deviation indications for
VOR [very high-frequency omnidirectional range], localizer approaches and five degrees of track for NDB [non-directional beacon] approaches.

How does one verify that one is on the correct vertical path by 500 AGL or 100' above the MDA when doing a a LOC approach ?

[RAT 5]

Finally, as stated in the TSB report,

"For a flight in FPA guidance mode, Air Canada’s practice was that, once the aircraft was past the FAF, the flight crews were not required to monitor the aircraft’s altitude and distance from the threshold, nor to make any adjustments to the FPA."
At Air Canada, the use of the distance/altitude table on the Jeppesen chart as a monitoring tool is not cited during pilot training for LOC/non-precision approaches"

What is Airbus recommended procedure regarding this? I've only flown Boeing, and a whole mess of other a/c, and I would never fly an NPA without using all the help I could get. Not monitoring ALT v DME was used in the 'dive & drive' type profile of ages gone by. Using FPA only would be like, in a less sophisticated a/c, setting a V/S at FAF and starting the watch and hoping. Why would you do that when you could make it safer monitoring ALT v DME? I'm curious if there are other Flt Ops who advocate that NPA technique and how that SOP can be approved the the CAA? There has to be a risk involved and this day of TEM why introduce any risk, especially when the statistics for CFIT show NPA's are the riskiest approaches. It doesn't seem common sense. I know what I'd do on such an approach. SOP does not say you are NOT allowed to use the ALT vDME table.

And, was it not reported some months ago that AC was making a claim against AirBus that the FPA system did not bring the a/c to the threshold as advertised? What happened about that? Surely the TSB report would have to investigate if the crew flew the profile according to Airbus procedures including any aspect of temp corrections and entries into MCDU.

Last Wx report was;
"wind 340°T at 22 knots, with gusts at 28 knots, visibility ¾ sm in light snow and drifting snow, broken cloud at 700 feet AGL, overcast cloud at 1000 feet AGL, temperature −6 °C, dew point −6 °C, and altimeter 29.62 in. Hg."
They were busy with that kind of weather..
So I doubt they would have been cross checking DME versus altitude inside the FAF, but that is speculation on my part.

If the automatics were in control of the a/c what would make them busy? Are you suggesting that in calmer weather they would have had time to do so even though it was not an SOP?

[wiedehopf]

Originally Posted by Gilles Hudicourt

I noted that several people asked why this runway does not have an ILS.

There are terrain features that prohibit the installations of an ILS, and one of those is if the terrain on the runway axis a certain distance before the threshold is nor fairly flat for a certain distance, in order for the Radio altimeter, which does not measure the height of the aircraft above the runway, but the height of the aircraft above the terrain directly below it, to be able to activate certain features such as flare mode, or changes flight laws, elevator trim, auto thrust etc. Even a dinosaur like the 737NG has such RA dependent features.

Such features would not work correctly if the terrain half a mile before the threshold was significantly higher or lower than the runway threshold.

I remember in a distant past flying ILS approaches in aircraft that did not even have a RA, but the aircraft I now fly prohibits ILS approaches if both RA are U/S.

Only problem would be with Cat II/III because they have a decision altitude based on the radar altimeter. Cat I ILS uses the barometric altimeter for minimums. Thus you can have dropping terrain approaching the runway.

And with Cat I there is of course no autoland. You say several features would not work, so how do they work on a visual approach to the same runway?

While i'm not saying an ILS could definitely installed at the location i would not be surprised if the non-existent ILS was just due to cost.

Edit: google says it is due to cost.

"The Halifax airport, and every other airport in the country, has financial constraints," Williams said. "They don't have an unlimited supply of money. And let me tell you, passengers would be the first to complain about increased costs if the airlines were required to pay for it."

http://www.cbc.ca/news/canada/nova-s...nway-1.3015771

[Retired DC9 driver]

RAT 5 wrote
"Using FPA only would be like, in a less sophisticated a/c, setting a V/S at FAF and starting the watch and hoping."

As I understand it, the FPA or Flight Path Angle is Inertial based,; it certainly isn't just a V/S you set. As the ground speed varies, the aircraft position relative to the desired FPA is adjusted by the autothrust to maintain the correct FPA. The idea of a Continuous Descent Approach, is that the aircraft is configured in the landing configuration and continuous descent, at Vapp and the FPA places you in a position relative to the runway for a Threshold Crossing Height of 50. With no thrust changes , or changes in rate of descent you should be at the MDA in a position to see the runway, disconnect autopilot and continue to landing..
In the old "Dive and Drive" LOC approaches, you would have a Missed Approach Point defined by a DME value or cross radial. Once you are past the FAF descending to MDA, then increase power to level off, and at the MAP (Missed Approach Point) if runway is not in sight, it's a Go Around.

[Retired DC9 driver]

Gilles wrote
"How does one verify that one is on the correct vertical path by 500 AGL or 100' above the MDA when doing a a LOC approach ?" In this case, an Airbus on LOC 05 to YHZ,
by correctly setting the published FPA at 0.3 DME from the FAF, then pull the knob. Check the FMA at the top of your PFD, that you are in FPA mode and proper angle is displayed.
This assumes you crossed the FAF at the correct altitude, coupled to the LOC . A Coupled/Selected approach.
No offense Gilles, but sometimes I wonder if the people on this thread are actually pilots, familiar with the automation in Airbus and Boeing aircraft.

see page 1.6.2 in the TSB report as to how the PFD, with FMA above should be displayed on this Coupled/Selected approach. Note the "Bird" ; Velocity Vector is displaced to the side by the crosswind.

ps. there is a small purple circle icon on right side of PFD that displays the FPA "path" (where the larger diamond would be a G/S indication). So that small icon VDEV displays if the aircraft is following the FPA vertical path correctly. The VDEV on the PFD is not to be used as a vertical descent aid.

[fireflybob]

Irrespective of company procedures or manufacturer "advice" I am staggered that any professional pilot would not be cross checking/monitoring any charted DME check heights on a non precision instrument approach.

[Capn Bloggs]

Originally Posted by DC 9 Driver

Gilles wrote
"How does one verify that one is on the correct vertical path by 500 AGL or 100' above the MDA when doing a a LOC approach ?" In this case, an Airbus on LOC 05 to YHZ,
by correctly setting the published FPA at 0.3 DME from the FAF, then pull the knob.

...No offense Gilles, but sometimes I wonder if the people on this thread are actually pilots, familiar with the automation in Airbus and Boeing aircraft.

A bit harsh, there DC9. What you have described might put an aeroplane on the correct path just after the FAF (you did cross the FAF in a 3° descent, I hope, so there was no balloon into the final descent...), but certainly doesn't ensure you will remain on that path. Unless you have an FMS-generated VNAV path to follow/coupled to, you'd better be following the DME profile down to the MDA (as FFbob noted) because what you've described is simply a point-and-shoot exercise, with you hoping you'll pop out with 2W/2R on the PAPI.

To Rat you said:

Originally Posted by DC9 Driver

As the ground speed varies, the aircraft position relative to the desired FPA is adjusted by the autothrust to maintain the correct FPA.

No it doesn't. If the aeroplane is bumped off the 3° path for some reason, it won't go back to it, it will simply re-set the flight path to 3°. The report describes this issue on page 65 and is something that any Airbus or Boeing driver should understand...

Further, I'm not an Airbus pilot but I very much doubt that the autothrust would control the vertical path: throttles control the speed, the pitch control controls the vertical path/FPA. That is what happens on my auto-jet. Just like they fly coupled ILSs. You get low, the stick comes back to correct. You get fast, the throttles come off.

[FlyingStone]

Originally Posted by Capn Bloggs

No it doesn't. If the aeroplane is bumped off the 3° path for some reason, it won't go back to it, it will simply re-set the flight path to 3°. The report describes this issue on page 65 and is something that any Airbus or Boeing driver should understand...

This should be the highlight of the whole topic here. Misunderstanding of the automation. People think because they do a nice LOC/FPA approach during their type rating with ISA conditions in still air in the sim FPA is great, set -3.0 degrees and pull 0.3 nm before FAF and that's it. Yep, unless it's -30C or +45C and bumpy as hell.

The only half bullet-proof tool for NPA is a VNAV coupled approach, with all the altitudes corrected for cold temperature. And even then, one should crosscheck with DME table until visual or there's no more entries in the table.

[slast]

Originally Posted by fireflybob

Irrespective of company procedures or manufacturer "advice" I am staggered that any professional pilot would not be cross checking/monitoring any charted DME check heights on a non precision instrument approach.

Unfortunately not as simple as it sounds as the chart DME heights also need to be cold-temp corrected.

It appears that Air Canada got the approval of Transport Canada for a chart in the QRH (not shown in the report) that gave low temp corrections for FAF altitude and the MDA, rounded up to the nearest 100ft, and for the FPA itself. The numbers were apparently correctly extracted for these. But there is no mention of DME altitude corrections, which could be different for each approach and not easily amenable to 100 ft rounding since they would actually become less than 100ft as the aircraft descends.

Once the descent was started the aircraft was ALWAYS below the intended flight path. But using the indicated altitudes against the basic chart values would have produced the following indications:

6 DME indicated alt 2080 = 140 ft HIGH when actually 40ft LOW
5 DME indicated alt 1650 = 70 ft HIGH when actually 70ft LOW
4 DME indicated alt 1240 = 10ft LOW - near correct but actually 110ft LOW
3 DME indicated alt 840 = 80 LOW when actually 150 ft LOW.

Which brings to mind the question of what procedures AC used to deal with this situation for older aircraft, without a FPA facility?

[RAT 5]

Which brings to mind the question of what procedures AC used to deal with this situation for older aircraft, without a FPA facility?

And also, for an operator that spends a good deal of its time in winter operating in sub-zero temps, how can they devise what appears to be a less than ideal method for its crews to conduct NPA's in said nasty conditions. One would have thought they were expert in winter ops: and how can that apparently less than ideal method have been approved by an equally supposed winter op experienced XAA? And if their methods are less than ideal, what have they done about it, and been required to do about it PDQ. It's already getting cold up there.
Is all that off target or am I misunderstanding?

[Retired DC9 driver]

Well I guess I have stirred up some discussion
Ok, I correct my previous statement, for RAT and Capt Bloggs
"As the ground speed varies, the aircraft position relative to the desired FPA is adjusted by the autothrust and pitch to maintain the correct FPA."

[fireflybob]

Unfortunately not as simple as it sounds as the chart DME heights also need to be cold-temp corrected.

slast, I agree and as RAT 5 has alluded to above I rather assumed that an operator that spends much of it's time in sub-zero temps would do this as a matter of course.

[J.O.]

On top of all the very valuable discussion which has helped my understanding of how it happened, I still struggle with the notion that a "non-precision" approach had such a ridiculously low MDA. It helped to set this crew up for failure, IMHO.

[Gilles Hudicourt]

Originally Posted by slast

Unfortunately not as simple as it sounds as the chart DME heights also need to be cold-temp corrected.

It appears that Air Canada got the approval of Transport Canada for a chart in the QRH (not shown in the report) that gave low temp corrections for FAF altitude and the MDA, rounded up to the nearest 100ft, and for the FPA itself. The numbers were apparently correctly extracted for these. But there is no mention of DME altitude corrections, which could be different for each approach and not easily amenable to 100 ft rounding since they would actually become less than 100ft as the aircraft descends.

Once the descent was started the aircraft was ALWAYS below the intended flight path. But using the indicated altitudes against the basic chart values would have produced the following indications:

6 DME indicated alt 2080 = 140 ft HIGH when actually 40ft LOW
5 DME indicated alt 1650 = 70 ft HIGH when actually 70ft LOW
4 DME indicated alt 1240 = 10ft LOW - near correct but actually 110ft LOW
3 DME indicated alt 840 = 80 LOW when actually 150 ft LOW.

Which brings to mind the question of what procedures AC used to deal with this situation for older aircraft, without a FPA facility?

The way I see it is to comply with that "Second Gate" they have in their procedures, the AC crew could have chosen one of the DME fixes from the chart that most closely matched a point that was either at 500 feet AGL, or 100 feet above the MDA, computed it's cold temperature corrected indicated altitude, and used it to evaluate where they were relation to the required slope. If too low, as AC does not allow FPV corrections after the FAF, then they would have called for a Go Around, as per the SOP.

The crew might have done all of this mind you. We just don't know, for the TSB authors, or the lawyers that later edited the original report, decided it was not necessary to include this information in the report.