AF B772, GPWS averts CFIT
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Ps. JammedStab I think that we had a good procedure of mostly having the different display on both. Seen couple of times how they can disagree at Tkof mode. The spare Horizon is not there for nothing...
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Groucho
The question was why they were "cruising" at FL90. My question was why is that determined to be "strange" and I asked why?
Yes - there are rules for flying below MSA, and I am not saying those rules were followed when they deviated. But that was not the question.
So I ask you, as a stated professional pilot, what cruising FL you would expect / choose / fly / could achieve in a widebody with a sector length of ~60NM?
And I also ask you, how and where has it been stated that the route, as planned, had an MSA of >FL90?
"Out of interest, why?"
Probably, Nigel, for the same reason that many professional pilots find it odd too. I'm sure you know (or should know!) that flying below MSA IMC is only OK under radar or on a procedural cleared route where that level or above is acceptable. To then 'divert' off that route at FL90 without a **** clue where the hard stuff is is OK with you?
Probably, Nigel, for the same reason that many professional pilots find it odd too. I'm sure you know (or should know!) that flying below MSA IMC is only OK under radar or on a procedural cleared route where that level or above is acceptable. To then 'divert' off that route at FL90 without a **** clue where the hard stuff is is OK with you?
Yes - there are rules for flying below MSA, and I am not saying those rules were followed when they deviated. But that was not the question.
So I ask you, as a stated professional pilot, what cruising FL you would expect / choose / fly / could achieve in a widebody with a sector length of ~60NM?
And I also ask you, how and where has it been stated that the route, as planned, had an MSA of >FL90?
Later, while turning right towards Douala the EGPWS of the aircraft issued a terrain warning and called "PULL UP!" which the crew complied with climbing the aircraft to FL130, where the EGPWS stopped the warnings. The aircraft subsequently continued for a safe landing in Douala.
The French BEA reported in their weekly bulletin that the occurrence was rated a serious incident, the French BEA is investigating the serious incident.
My note: MSA there is 15700 ft
The French BEA reported in their weekly bulletin that the occurrence was rated a serious incident, the French BEA is investigating the serious incident.
My note: MSA there is 15700 ft
Did the crew climb until the warnings stopped or until they made MSA? I read somewhere that EGPWS warnings stop by design before a safe level off can be achieved.
The French BEA would do us all a favour by ensuring that airline training departments and pilots take EGPWS warnings seriously by vigorously & correctly flying the escape manoeuvre - that is, climb until at least MSA.
Did the aircraft really make a "safe landing" or was it just dumb luck, or Providence, that there wasn't a CFIT as the disoriented crew levelled off below MSA?
Last edited by pithblot; 22nd May 2015 at 21:27.
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Shooting down people involved in accidents or incidents seems to have become the favorite passtime here.
If you know a bit the place you wil find that both airports are at sea level, the whole route is above sea. For a roughly 50 NM leg going easbound, FL90 is a good and correct level . No high MSA in there.
How about this ( speculation )
You take off , take course 060 and find a CB in the middle of the route, you are 3 in the cockpit , you look at the Wx radar , discuss it, and decide to go left. How long you wander left and why unoticed for so long is most probably the issue.
Because when you are clear of the Wx and decide to turn right back to DLA , bingo the EGPWS wakes you up and you find out there is Mt Cameroon in between.
Now a bit of pontification to the Non-pros here :
Because you are profesional you make a report of this to avoid others to make a similar mistake, and your airline, passes it on to the Investigation Board, which, because it is professional organisation publishes it so that other operators can learn from this and avoid it too.
Another possible scenario, Eastern 401 L-1011 in Everglades .
Every professional will read the report in a few months and the system will probably be a little safer as whole.
Throwing stones at people/airlines /countries will set us back 40 years, where nothing "embarassing" was ever reported.
So keep it cool guys, it is good to have reports like this.
If you know a bit the place you wil find that both airports are at sea level, the whole route is above sea. For a roughly 50 NM leg going easbound, FL90 is a good and correct level . No high MSA in there.
How about this ( speculation )
You take off , take course 060 and find a CB in the middle of the route, you are 3 in the cockpit , you look at the Wx radar , discuss it, and decide to go left. How long you wander left and why unoticed for so long is most probably the issue.
Because when you are clear of the Wx and decide to turn right back to DLA , bingo the EGPWS wakes you up and you find out there is Mt Cameroon in between.
Now a bit of pontification to the Non-pros here :
Because you are profesional you make a report of this to avoid others to make a similar mistake, and your airline, passes it on to the Investigation Board, which, because it is professional organisation publishes it so that other operators can learn from this and avoid it too.
Another possible scenario, Eastern 401 L-1011 in Everglades .
Every professional will read the report in a few months and the system will probably be a little safer as whole.
Throwing stones at people/airlines /countries will set us back 40 years, where nothing "embarassing" was ever reported.
So keep it cool guys, it is good to have reports like this.
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If you know a bit the place you wil find that both airports are at sea level, the whole route is above sea. For a roughly 50 NM leg going easbound, FL90 is a good and correct level . No high MSA in there
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Having previous experience in this part of the world, it is easy to see how this could happen. A 60nm sector in this aircraft will take about 15mins from wheels up to wheels down. If you add all of the flight deck procedures that need to be done to configure, you are a busy body. Now add to this unhelpful ATC, broken Nav Aids, and the worst weather you are likely to encounter anywhere in the world, the mixture becomes even more difficult. Bearing in mind, flying into a CB that extends up to 60,000ft will have the same effect as flying into Mt Cameroon, and with these airbourne mountains covering much of your sky, your attention may be drawn to the radar display at this point. I think for any pilot that has not experienced this area of operation should not be so critical of this crew. The installed system worked as designed - a disaster was averted - and we can all learn from this.
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EGPWS is a back up system. Terrain awareness/altitude awareness is a basic of instrument flying. MEA/MOCA/MSA/Grid MORA. If you're not on a printed line (MEA/SID/STAR altitude restrictions) it's up to the crew to decide if MSA protection is provided(ie above MSA for the portion of the MSA circle that you're in). If MEA or MSA protection isn't guaranteed, and basic terrain awareness isn't available(terrain chart/minimum radar vectoring chart), then you need to operate above the grid MORA.
Yes, the system, because of the backup safety system, worked. It's not supposed to rely on the backup system. There's a reason why a EGPWS alert is usually a mandatory reporting event, because it's not supposed to happen in the first place.
Yes, the system, because of the backup safety system, worked. It's not supposed to rely on the backup system. There's a reason why a EGPWS alert is usually a mandatory reporting event, because it's not supposed to happen in the first place.
I remember a case where a 737 crew recieved a GPWS alert around FL100 during an approach in bad weathher in a mountainous region. They zoomed up to FL200+ until the alarm eventually silenced.
The investigation showed they where never close to terrain and attibuted the alarm to hail.
The investigation showed they where never close to terrain and attibuted the alarm to hail.
DJ77
In IMC you act on GPWS warning. When out of the warning condition, then you start analyzing. You don't have time to think that it might be wrong, because if it comes on and if it's wright, you're not where you think you are.
In IMC you act on GPWS warning. When out of the warning condition, then you start analyzing. You don't have time to think that it might be wrong, because if it comes on and if it's wright, you're not where you think you are.
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GPWS (pre EGPWS) -
After making a crossing restriction the midnight crew accelerated for a high speed climb. GPWS - Terr....Pull... Both radar altimeters flash to below 200' and just as quickly the radar altimeters go away. So the crew thinks they've got a maintenance write up.
That morning the FO starts looking at terrain maps ... "And that's when I started shaking..."
After making a crossing restriction the midnight crew accelerated for a high speed climb. GPWS - Terr....Pull... Both radar altimeters flash to below 200' and just as quickly the radar altimeters go away. So the crew thinks they've got a maintenance write up.
That morning the FO starts looking at terrain maps ... "And that's when I started shaking..."
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Misd:
AAL 965, the 757 CFIT near Cali, Colombia, was also equipped with plain old GPWS. There was an informal consensus that had they retracted the spoilers immediately upon hearing the first "Whop! Whop! Pull Up!" put the throttles to the stops, while rotating, they may very well had cleared the ridge-line.
But, had that happened, it was problematic what their subsequent action would have been, for there was higher terrain to the left and straight-ahead. A climbing turn to the west would have worked, though.
That was the accident that resulted in EGPWS.
GPWS (pre EGPWS) -
After making a crossing restriction the midnight crew accelerated for a high speed climb. GPWS - Terr....Pull... Both radar altimeters flash to below 200' and just as quickly the radar altimeters go away. So the crew thinks they've got a maintenance write up.
After making a crossing restriction the midnight crew accelerated for a high speed climb. GPWS - Terr....Pull... Both radar altimeters flash to below 200' and just as quickly the radar altimeters go away. So the crew thinks they've got a maintenance write up.
But, had that happened, it was problematic what their subsequent action would have been, for there was higher terrain to the left and straight-ahead. A climbing turn to the west would have worked, though.
That was the accident that resulted in EGPWS.
@ Miraculix. You missed my point.
In this thread most posts (including the title) assume a priori that a CFIT has been averted close to Mt Cameroon. Very possibly it may be what happenned but, please, let's not anticipate and draw definitive and patronizing conclusions (as usual on R&N) before the real story is known.
In this thread most posts (including the title) assume a priori that a CFIT has been averted close to Mt Cameroon. Very possibly it may be what happenned but, please, let's not anticipate and draw definitive and patronizing conclusions (as usual on R&N) before the real story is known.
