JJA4, I will try to confirm your conclusions or otherwise, but a major problem is that we can only go by the TSB report which raises MANY unanswered questions that I cover in the critique referenced previously.
Originally Posted by
Jet Jockey A4
- The crew did not program the right flight path into the aircraft's FMCs because they were below the temperature corrected flight path.
The flight path was programmed according to AC's procedures, as far as I can tell. However there are questions about what the temp-corrected angle should have been; the descent initiation point; a rounding error (exact angle could not be set); and how "wind variations" could have affected the FPA actually flown. Also in my opinion although it seems nuts not to have any crosschecks on the way down, the way Air Canada implemented temperature corrections made this difficult. Overall one can only say that the crew seem to have actually conducted the instrument descent in accordance with the SOPs they had been given. (Report para 1.18.3). There is no question the the flight path achieved did not bring the aircraft to the correct point, and this was not detected by the crew. But who was responsible for that is not clear.
Originally Posted by
Jet Jockey A4
You can't rely on the radar altitude call out at 400' or 100' because of the terrain. In fact when the auto calls at 400' and 100' were given they were actually a lot closer to the ground then one would expect.
Correct. The terrain profile on my chart was a screen grab from the TSB presentation crosschecked against Google Earth.
Originally Posted by
Jet Jockey A4
The PM's call of "minimums, lights only" came at or slightly below the uncorrected cold temperature MDA, perhaps 50 to 60 feet below what the corrected MDA was on that night.
Correct as possible without FDR/CVR
Originally Posted by
Jet Jockey A4
The captain's call of "landing" came at an even lower uncorrected MDA.
Likewise.
Originally Posted by
Jet Jockey A4
At approximately 150' above ground, both pilots have a "conversation" about the approach lights.
Originally Posted by
Jet Jockey A4
Autopilot disconnect happens at less than 50' above ground. It would be interesting to know the A320's autopilot minimum descent limits are on a non precision approach.
Disconnect was about 30ft above threshold elevation, 16 ft above touchdown zone elevation. The minimum autopilot height was MDA -50 but the report does not say whether the MDA had been entered in the FMC or whether the crew observed the "disconnect A/P" warning - one of the many failings in the report.
Originally Posted by
Jet Jockey A4
The captain's G/A initiation starts below the RWY's threshold altitude with the known consequences.
Close to or below. Certainly below the TDZ elevation.
Originally Posted by
Jet Jockey A4
I am not an expert in crash analysis but it sure looks to me that the crew busted minimums without having the proper visual clues to continue below the MDA. This might have been further compounded by several technical errors from them in the way they programmed the FMCs (I'm not qualified on the A320) and did not apply the temperature corrected altitudes at least at the MDA.
But the report is quite specific that "the crew" had the legally required visual reference at the MDA. The crew actually followed the law and their procedures and still crashed! But nobody was killed. I wonder if that is why the report has been able to get away with not even mentioning any of the implications of that astonishing fact. This time, it wasn't all the crew's responsibility - so whose was it?