From the first hints, Air Asia QZ8501 climbed at 6000 fpm before stalling.


http://m.bbc.com/news/world-asia-30902237

Could the aircraft have been taken in a very strong updraft, abruptly interrupted or followed by a downdraft?

"No fighter jet would attempt to climb so fast"

That's the standard of reporting!

quote:

Originally posted by Rockdoc:
"No fighter jet would attempt to climb so fast"

That's the standard of reporting!

Plus stalling occurs because the nose is pointed upwards for too long during the climb....

Leave aside the idiocy of the reporter... The point is that shortly before to crash, the aircraft suddenly climbed far beyond its normal climbing rate. Shortly before, the pilot had requested a change in flight level to avoid weather.

I have been myself in an airliner caught in an updraft (on a go around initiated after passing the threshold, had it been a downdraft instead we'd have made it on CNN...), where we took 2-3 Gs for several seconds, twice. I figure that an exceptional updraft could exceed the design limits, and/or create an unrecoverable situation.

The Air France crash profile was eerily similar. They were doing 7000 FPM up before they stalled. I'm thinking we might hear something about frozen Pitot tubes and alternate flight control laws on this one too......Maybe.

quote:

Originally posted by surestrike:
The Air France crash profile was eerily similar. They were doing 7000 FPM up before they stalled. I'm thinking we might hear something about frozen Pitot tubes and alternate flight control laws on this one too......Maybe.

Once we see the DFDR readout we will know for sure, but SureStrike appeares to have nailed it.

Interesting thread on A320 stall recovery. We may be hearing more on this.

http://www.pprune.org/tech-log...overy-procedure.html

That procedure is not really all that mind blowing and different from any other nose high unusual recovery in a transport category jet. ANY jet with under slung wing mounted engines will have a natural tendency to pitch nose up when adding power. In fact at TOGA thrust with aircraft nose up at low airspeed you might not have enough elevator authority to overcome the nose up pitch force when adding max thrust. So it only makes sense to do as Airbus recommends in that procedure.

Your other option of course when your nose is high and your airspeed is slow is to roll into 60 to 80 degrees of bank and push a little bottom rudder, slicing the nose down to the horizon then roll wing level and add power. That is actually a much better procedure as you don't unload and go negative possibly causing your engines to flame out. It's also a more comfortable ride than pushing over and going negative.

G, thanks, always appreciate your in depth knowledge and posts in these matters.

Surestrike, recent reports indicate PIC left his seat and tripped the circuit breakers to the flight computer. What's your take on this related to the sudden pitch up and stall?

Bobster,

I don't know but my my guess would be that he lost both FACs and when he tried to reset them via the over head switches they wouldn't reset so he was trying to reset the associated circuit breakers to try and get them back. I am still heavily suspicious of pitot ice as being the cause of the FACS failing in the first place.

I have no idea why the pilot flying would have pitched nose up other than a primary flight display blanking out possibly.

If this is a rerun of the Air France crash that would be very sad and disturbing, given that the findings and recommendations have been out there a while.

I guess only mandatory replacement of the Thales(?) pitot tubes would fix this?

quote:

Originally posted by Philip A.:
Leave aside the idiocy of the reporter... The point is that shortly before to crash, the aircraft suddenly climbed far beyond its normal climbing rate. Shortly before, the pilot had requested a change in flight level to avoid weather.

I have been myself in an airliner caught in an updraft (on a go around initiated after passing the threshold, had it been a downdraft instead we'd have made it on CNN...), where we took 2-3 Gs for several seconds, twice. I figure that an exceptional updraft could exceed the design limits, and/or create an unrecoverable situation.

Funny, given the weather situation reported , that was the first thing that came to my mind.

Grizz

What a wealth of knowledge we have on this forum! I enjoy these so much!

OK, here is a purported pic of a A320 instrument panel. http://img.planespotters.net/p...ottersNet_174866.jpg

Looks like no analog gauges at all? If the FAC's were out, the PIC was faced with a total blank screen and had no way to know WTF was going on. Should there be some rudimentary analog feedback? A standard altimeter and artificial horizon would tell you most of what you need to know to keep things level.

Back in the day when I was taking flying lessons, my instructor would tape over certain instruments, put the hood on me and then put the aircraft into a "challenging" situation. I was required to stabilize the aircraft using only a few instruments.

Bobster,

Circled in red is the SAI Standby Attitude Indicator which is also a mini PFD Primary Flight Display. The SAI gets attitude data from an independent source from left or right PFD's and in case of a total electrical failure has an independent and separate battery which supplies power to the SAI for a minimum pf 30 minutes.

The FAC's Flight Augmentation Computers don't control the primary flight displays but they give it input.

Take a look here..

http://www.efbdesktop.com/flig...trols/sys-7.5.3.html

And here..

http://www.dutchops.com/Portfo...Flight_Controls.html

Here is a very good description of the PFD's and the large volume of information that this instrument gives the pilot. In a glass airplane the PFD is the center of your world.

http://ozten.net/aviation/A321/320/fwd/pfd1.html

Interesting seems like there is some decent info here. I am typed in the 320 and flew it for 8 years. Airbuses are interesting airplanes for sure. While there may have been some sort of mechanical failure and weather issues in this recent crash the airfrance incident boiled down to pilot error. These planes are flyable without all the fancy stuff, even pitot tubes and FACs. If you fly into a severe thunderstorm all bets are off. But it seems basic stick and rudder skills are inadequate especially in these developing countries. An Asian airline just lost an ATR72 on an apparent engine failure on takeoff. This is a basic maneuver that is taught from day one in multiengine aircraft. Flight crew training and experience is going to be a major factor in the future as these countries buy airplanes. The ab initio training programs do not give the breadth of experience from the days past. Pulling breakers to your FACs while out of your seat in weather with a probably very inexperienced FO at the controls sounds desperate to me at least. Interesting to hear what the report will be.

Yeah, these occurrences remind me of the Star Trek Next Gen episode where they ran into a civilization that made their living stealing technology from more advanced species. When things go wrong it turns into a goat rope when you lack the skills and knowledge. You can buy/lease technology but you may not be able to handle it. Look for calls to make commercial planes run totally by computers to rule out the human factor. Human pilot on board for last ditch backup.