Turkish Airlines cargo 747 crashes in Kyrgyzstan
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Notwithstanding the complete lack of awareness during the arrival/approach, had they flown the GA correctly they'd probably have got away with it. According to the report:
01:17:05 - Pass DH
01:17:07 - FO states 'minimums'
01:17:08 - Capt states 'negative' (not visual)
01:17:09.5 TOGA pressed
So, the GA was initiated 4.5 seconds too late. Had they initiated the GA correctly ('at or before DH') we'd be none the wiser about their astonishingly inept approach!
01:17:05 - Pass DH
01:17:07 - FO states 'minimums'
01:17:08 - Capt states 'negative' (not visual)
01:17:09.5 TOGA pressed
So, the GA was initiated 4.5 seconds too late. Had they initiated the GA correctly ('at or before DH') we'd be none the wiser about their astonishingly inept approach!
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Hi guys,
I'm having a bit of trouble understanding what's going on in that report. Looking at figure 1, it looks like the aircraft captured the 9 degree glideslope, with a VS of 1400fpm.
My understanding is that when the GS is lost, the AP will continue in an "inertial mode" descent, with the associated failure flags. What I don't get is why the aircraft seemed to descend on a 3 degree slope, parallel to the GS, instead of the 9 degree slope that it had captured. Why wouldn't it continue at 9 degrees?
I'm having a bit of trouble understanding what's going on in that report. Looking at figure 1, it looks like the aircraft captured the 9 degree glideslope, with a VS of 1400fpm.
My understanding is that when the GS is lost, the AP will continue in an "inertial mode" descent, with the associated failure flags. What I don't get is why the aircraft seemed to descend on a 3 degree slope, parallel to the GS, instead of the 9 degree slope that it had captured. Why wouldn't it continue at 9 degrees?
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Why wouldn't it continue at 9 degrees?
The real question is: How can you cross two markers (Outer and middle) without doing an altitude check? The according numbers are on the approach chart, so no math included. Dead simple crosscheck, but not done.
If you do no crosschecks, you are not allowed to do any mistake or darwin gets you.
My take is that the system error checking is more than just loss of the glideslope signal but also 'reasonableness' of the signal. Obviously a 9° slope is not reasonable, hence error flags and reversion to an inertial 3° descent waiting for a reasonable signal to return. In this case it never did because the aircraft was never near the correct 3° path.
"Hey skipper, we are there. Bring here down."
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Volume & Bleve,
So you're saying the system just defaults to a 3 degree path? What if you were flying a 2.5 degree glideslope? I have one such glideslope near me.
To be clear, I'm less concerned about the (in)actions of the crew, and more interested in the system logic.
So you're saying the system just defaults to a 3 degree path? What if you were flying a 2.5 degree glideslope? I have one such glideslope near me.
To be clear, I'm less concerned about the (in)actions of the crew, and more interested in the system logic.
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Hello Check Airman,
It is all a matter of careful wording, either in posts or in (reports about) reports.
In official Boeing documentation, there is a description of how the autoflight system monitors ILS signal for interferences, and how it will act to pass through such a phenomenon if it is short lived or if it persists. This description mentions that the system will maintain an inertial path, but does not attatch numbers to that description.
That description leaves room for interpretation and you can bet your 2 cents that the way the system works will be logical for the way an aircraft flies: if the ILS glideslope happens to be 3 degrees and, once established on the slope, the signal is lost for a short while, then the inertial path will be 3 degrees. If the slope was for 2.5 degrees, then the inertial path will be 2.5 degrees.
In this particular case, the aircraft started to intercept the 9 degree false glideslope - it never established a steady situation, the signal irregularity happened during slope acquisition. In that case, the most logical "best guess" inertial path would be 3 degrees, the "standard ILS slope" until a good quality signal would appear again. In this case, the inertial period lasted so long, that the proper warnings were given by the system, an AUTOPILOT Eicas Caution and AMBER LINE drawn through the pitch FMA. The proper reaction to those conditions is the immediate start of a Go Around.
You must realize that there is a lot of clever algorithm stuff in autopilot systems: for instance, most ILS glideslope intercepts are made from below the slope, in level flight - so you have a period where the ILS deviation would suggest to fly UP to the slope middle line. In reality, the A/P will maintain level flight until it hits the center of the slope.
A false 9 degree slope may exhibit a reversal of signal: fly DOWN when below the middle line, fly UP when above it. Whether or not the signal is reversed depends on the type of antenna array that is employed for the G/S signal. The A/P logic must filter and smooth all the signals and aircraft control commands so that no abrupt and illogical moves are made. The user manual descriptions will never be detailed enough to describe exactly how all that is accomplished.
What the user manuals do very well though is the bottom line - if things are not going in the way they should be going, GO AROUND! I mean, 1 mile to go to the threshold and being 2.000 ft above threshold elevation is a pretty simple indication that the situation is not as it should be.
It is all a matter of careful wording, either in posts or in (reports about) reports.
In official Boeing documentation, there is a description of how the autoflight system monitors ILS signal for interferences, and how it will act to pass through such a phenomenon if it is short lived or if it persists. This description mentions that the system will maintain an inertial path, but does not attatch numbers to that description.
That description leaves room for interpretation and you can bet your 2 cents that the way the system works will be logical for the way an aircraft flies: if the ILS glideslope happens to be 3 degrees and, once established on the slope, the signal is lost for a short while, then the inertial path will be 3 degrees. If the slope was for 2.5 degrees, then the inertial path will be 2.5 degrees.
In this particular case, the aircraft started to intercept the 9 degree false glideslope - it never established a steady situation, the signal irregularity happened during slope acquisition. In that case, the most logical "best guess" inertial path would be 3 degrees, the "standard ILS slope" until a good quality signal would appear again. In this case, the inertial period lasted so long, that the proper warnings were given by the system, an AUTOPILOT Eicas Caution and AMBER LINE drawn through the pitch FMA. The proper reaction to those conditions is the immediate start of a Go Around.
You must realize that there is a lot of clever algorithm stuff in autopilot systems: for instance, most ILS glideslope intercepts are made from below the slope, in level flight - so you have a period where the ILS deviation would suggest to fly UP to the slope middle line. In reality, the A/P will maintain level flight until it hits the center of the slope.
A false 9 degree slope may exhibit a reversal of signal: fly DOWN when below the middle line, fly UP when above it. Whether or not the signal is reversed depends on the type of antenna array that is employed for the G/S signal. The A/P logic must filter and smooth all the signals and aircraft control commands so that no abrupt and illogical moves are made. The user manual descriptions will never be detailed enough to describe exactly how all that is accomplished.
What the user manuals do very well though is the bottom line - if things are not going in the way they should be going, GO AROUND! I mean, 1 mile to go to the threshold and being 2.000 ft above threshold elevation is a pretty simple indication that the situation is not as it should be.
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This description mentions that the system will maintain an inertial path, but does not attatch numbers to that description.
In the pitch chanel the A/P will maintain an inertial path which tracks a constant 3° slope regardless of the actual glideslope angle at a certain aerodrome
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Maybe it's been alluded to already ... but of the approach, had there been an observant check airman looking over the FO's shoulder during its conduct, what would he or she have said, and when would he or she had said it? And if that person had had an "attention getter" in their lap....say a short length of 2x4...at what point might they have used it?
Maybe it's been alluded to already ... but of the approach, had there been an observant check airman looking over the FO's shoulder during its conduct, what would he or she have said, and when would he or she had said it? And if that person had had an "attention getter" in their lap....say a short length of 2x4...at what point might they have used it?
I hope it wasn't kind of nepotism...
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And if that person had had an "attention getter" in their lap....say a short length of 2x4...at what point might they have used it?
I'm always amazed at people who sit there and watch as someone tries to kill them, not doing much. I'm lucky that it has happened very rarely; only the occasional moment my wife is driving and goes into a red-mist moment about some perceived misdemeanour of mine. There are no CRM skills dreamt of that can solve those moments. 2x4 in a confined space is difficult. Tasers might have the calming effect as we crash into whatever is in front of us; and the threat of same will be a bluff-calling standoff. Theory in a classroom is great, but in real life it somehow doesn't always work as planned. Not easy times, especially with cockpit gradients in some places getting very steep; and the monkey is not always in the seat you'd expect.
I'm always amazed at people who sit there and watch as someone tries to kill them, not doing much. I'm lucky that it has happened very rarely; only the occasional moment my wife is driving and goes into a red-mist moment about some perceived misdemeanour of mine. There are no CRM skills dreamt of that can solve those moments. 2x4 in a confined space is difficult. Tasers might have the calming effect as we crash into whatever is in front of us; and the threat of same will be a bluff-calling standoff. Theory in a classroom is great, but in real life it somehow doesn't always work as planned. Not easy times, especially with cockpit gradients in some places getting very steep; and the monkey is not always in the seat you'd expect.
Authority gradient?
With the proviso that we have no facts about the actual cockpit duties and interactions yet, the authority gradient issue assumption implies that that the Captain was at the controls and the F/O did not intervene. There is of course a very simple way to eliminate this situation.... have the F/O set up and fly the approach under the Captain's supervision, prior to the Captain confirming the landing, whether automatic or manual. As a broad generalisation, I suspect Captains are less likely to allow F/Os to kill them than vice versa.......
Leads hobby-horse back into stable .....
Leads hobby-horse back into stable .....
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With the proviso that we have no facts about the actual cockpit duties and interactions yet, the authority gradient issue assumption implies that that the Captain was at the controls and the F/O did not intervene. There is of course a very simple way to eliminate this situation.... have the F/O set up and fly the approach under the Captain's supervision, prior to the Captain confirming the landing, whether automatic or manual. As a broad generalisation, I suspect Captains are less likely to allow F/Os to kill them than vice versa.......
Leads hobby-horse back into stable .....
Leads hobby-horse back into stable .....
Unfortunately it was on one aircraft type only for a limited period of time...
Isn't that the BA "Monitored approach?" It also has the advantage of eliminating the transition from clocks to visual reference. The monitoring pilot has the eyes adjusted to outside the cockpit and if he/she says, "Nothing seen, go around" the other pilot is already on instruments and simply performs a missed approach.
Done it both ways & I quite liked that system.
Done it both ways & I quite liked that system.