THS, currents, automation
 

We have one pic of purported bulkhead with THS by one A320 mechanic, a quite different pic found online purported to be A320 THS bulkhead, one post other than my previous noting the significant differences, and no further comments confirming one or the other. We've had no precise description of the structure on which the FDR is mounted, other than aft of the pressure bulkhead in the unpressurized tail. The FDR is on or near this bulkhead. Resolving the discrepancy should not be difficult given Prune readership.

If as multiply described the tail is resting semi-inverted on vertical fin and right horizontal stab, access to the FDR should not be impeded by mud. The obstacles to investigation/recovery via diving have been ocean 'currents'. Distinctions between 'current', 'tide', and current tidal interactions in the area of search have not been made. Search reports about the process all cite limited visibility and strong currents. The first tail pics came from a time of 'unusual brief current calm', of which there has been little of since. Hi tech remains subservient to mud and currents.

As a pilot, and from pilots I have known, very few of the heavy pilots would say "If I had been in his position I'd be dead now." The self confidence needed to overcome doubt during command too easily condemns those who ended up dead as inadequate in some way. Yet every pilot has in their history instances of 'What he hell is going on".

I find the vociferous arguments between posters here claiming piloting mastery of specific flight control systems, but having completely conflicting views about how things actually work in specific but not impossible situations to be very disconcerting. That is why the issues of specific complex systems and human interface won't go away. If 95% of posters here had the same opinion about how systems work in unusual situations there would be little discord, and a passenger could feel confident that training, experience, ATC and flight control system functionality were working together well.

The claim that flight control automation has saved more lives than it has cost, evidenced by lower accident rates, is an assertion that rides on the shoulders of improvements in component dependability, airframe structures, materials, aerodynamics, and better and more weather reporting. The claim may be true, but the amount of truth may be much lower if the safety improvements delivered by all other advances are removed from the calculation.

It looks to me that it broke up behind the pressure bulkhead. Compare this to the picture above. The pressure bulkhead is on the right, the jackscrew mount is on the left. This looks like the same place as the picture above is showing.

http://i337.photobucket.com/albums/n...aftBHtail1.jpg

There is something I don't understand about the flight condition this aircraft is assumed to have gotten itself into.

From what I've read here and elsewhere it seems that if a transport pilot who is trying to climb finds that he is ascending at a high rate (say 9,000 fpm), with airspeed dropping, the reaction from the pilot (or Hal inthe case of Airbus) is to pull out all the stops and push the yoke or the sidestick forward as far as it will go and even adjust stabilizer trim to get more nose down pitch - right?

It seems to me that any pilot who has flown gliders in the past would just smile ear to ear (and maybe even throw the plane into a sharp turn so as to not lose the updraft) while adding power to ward off any possibility of a stall and wait to kick out of the updraft if it hasn't already dissipated before delivering the craft to an altitude near the max altitude for the type.

Are planes and people being lost in order to stay within ATC assigned altitude?

Leightman 957:
Since no one knows what happened to this airplane yet, I can't see how anyone could say "I could do better than that" since we don't know what THAT even is yet other than the generic stay away from thunderstorms advice.

Propduffer: I was a right seat eyewitness to a plane about to be lost due to convective activity. The left seat PIC/student* was VERY willing to rip the plane up trying not to gain altitude and then managed to get a spiral dive going :eek: I had to take over to bail us out of the situation. Wings level, Va, and "unable to maintain altitude due to convective activity, we'll tell you when we level off" did the trick. 2,000 FPM + at idle power is a ride :) Until you get into ice or lack of O2 or mach limits or something :(

* The student was already comm/ir rated, not a n00b I would expect to do something like that.

@propduffer

8501 was in a busy airway, with another a/c at 36,000ft (I think?) coming along less than 15 miles behind, and crossing traffic at higher altitude up ahead. If an updraft was taking him through FL360 with dropping airspeed, he might be concerned about ATC not being able to manoeuvre everything else out of his way in time?

Thermalling an A320
 

Propduffer, I think your post is a bit cheeky. Us glider pilots are generally a very respectful bunch. The suggestion that the pilot was trying to (or perhaps failing to) thermal his A320 is a bit disrespectful. Whatever happened, the pilots were clearly overwhelmed by the situation.

@dash34 re: Propduffer -- I agree too cheeky in this tragedy, but I think he was (very clumsily) trying to make a different point about possible dangers of an artificially strict adherence to assigned FL (by pilot, but mainly by FMC) in extreme vertical weather. (Gliders seek out and utilize moderate vertical weather; airliners don't.)

Other questions in here about a primitive "fixed (gyro-only) attitude and power mode" for penetrating such weather (i.e. ignoring altitude and airspeed changes (within reason)) are getting at the same question/concern.

I mean there has to be some (rare but sometimes encountered) point where dangers of disorientation and/or FMC-caused extreme attitudes outweigh the danger of encountering another aircraft.

@Volume
I recall that the trim works as an averaging function of the pilot inputs. PF on 447 was "mixing the mayonnaise" using the side stick with strong bias to nose up function. If he had mixed mayonnaise totally randomly then trim averaging function would have been zero, no trim.

I find it hard to fathom that it could be the same as AF447. However how can we ignore the coincidences: possible ITCZ CB penetration, possible climb towards the top of the altitude envelope in warm air, possible max trim. At the least I think you will agree there is a high probability of pilot overload as a common factor.

I wasn't referring specifically to this incident, we don't even know for sure if my question relates to QZ8501.

My question was about how any or all transport pilots handle a strong updraft scenario. The glider reference was made just to make the point that being caught in an updraft is not a life threatening event. I left unsaid that I think putting a jet airliner in a vertical dive, especially with full power is almost certain to be a life threatening event. So it seems to me that SOP in the transport world is (in this case) far too focused on avoiding stalls while tending to ignore something far worse.

More to the point: Lessons Learned

Dash34
I am a glider pilot. And my point wasn't about "thermaling", is was about heads up seat of the pants flying. Realizing what is dangerous and what is not.

Propduffer:
What I was taught for thunderstorms by an old time airline pilot was what he called "soft ride". Autopilot in wing leveler mode - all heading and altitude controls off - power for Va, and keep wings level. Let the plane ride the up and downdrafts with gentle corrections and ease the plane back to your heading. Sure to drive ATC nuts but keeps stress low.

island_airphoto

That makes sense to me.

Is TCAS useful in that situation?

TCAS would alert other aircraft, of course, but it's a last resort, and other a/c may be equally challenged by the conditions and not well placed to take evasive action.

@propduffer

In all my thermalling in gliders, I never once was in fear of having its wings fall off. That's because the gliders I've flown (ASK25/Discus/Duo Discus/Nimbus) are rated to +6/-3G, plus margin.

You're forgetting that an airliner does not have those limits, they're only rated from +2.5/-1G, a load factor *easily* achieved or exceeded when penetrating or washing out of a hefty CB updraft. That's why in the Airbus flight control computer logic, load limitation ranks supreme to the point of deploying spoilers to decrease lift and positive G moment. Also, you're forgetting that turbulence near the performance envelope's end is a very different story than down low where you have ample reserve to deal with over/under speed situations. At FL360, the A230 has probably 30 odd kts of range between overspeed and onset of the yellow ribbon... that's not much to play with when your coffee goes flying over the dash and into your controls. Speaking of which, there's another theory for the theorists amongst you: avionics malfunction due to spilled coffee in turbulence. >:->

But in terms of flying my 744 into a CB, I will do anything I can to avoid overstressing the old lady, and any equally trained airline pilot will, too. That includes announcing an altitude block to ATC (formally it's a request, but ATC knows there's nothing I can do so they comply).

Perhaps we can just this once exercise restraint at blaming incompetent crew. Just because they're flying for a third world low cost carrier doesn't mean they weren't decent pilots. The only evidence we have thus far is

1) some combination of airframe and cockpit crew was likely responsible for this crash
2) lots of other flights in the vicinity did not encounter problems

hell for all I know they got hit by a meteorite.

Yes I think Propduffer was being a bit irreverent... ;)

On the glider pilot /updraught debate it has been my experience that when entering a thermal/updraught things in practice are not necessarily what one might imagine, as far as threat of a stall is concerned.

Because there is a net addition of energy to the aircraft 's frame of reference by buoyant rising warm air airstream, equivalent to an accelerated state, there is little or no danger of stalling... and leaving the pitch state and trim alone is a very reasonable course of action.*

...with the proviso on freedom of altitude change**

The danger is having net aircaft energy (PE + KE) reduced... classic wrong end of windshear
or entering downdraught - what a glider or low wing loading pilot would call 'going over the falls'.
that's when we need to stick forward and keep the a/c flying.

... it is unfortunate that these basic micrometeorology principles seem a world apart from a modern pilots training or experience.

and I think a point worth thinking through.

On another tack... I am reflecting on any part the Maint. Tech may have played if in the cockpit.

** in CB weather / ITCZ regions why are aircraft being vectored with no regard
for prevailing or likely weather/upset. Common sense would dictate much wider margins
And altitude freedoms ?

physicus sez: By Jove, that's the first sensible thing said in this whole thread! :8

A couple of things: Is that the FDR at the bottom of the photo in post #1570 ? And in the photo in post #1567, it appears that we are seeing the from the 'C' in the registration number forward on the left side (PK-AXC, that piece being upside-down). The break being behind that, wouldn't this be the forward section of the plane (or part of it)? Not the tail.

If that is the FDR, actually mounted to the pressure bulkhead, and if this is where the fuselage broke, the recorders could be in the debris between the sections.

And now that the tail (and other parts) have been located, has anyone reported hearing a pinger?

Boy it's nauseating reading all the amateur speculation on this thread. What is written above is akin to saying " From what I've read it seems that if a builder who is trying to build a house finds that the walls are falling down, his reaction is to whip out his mobile phone and order the concrete truck to return and then put more concrete in the foundations while using stainless steel brackets to reinforce the internal walls".
Seriously, that's how stupid it sounds to an airline pilot.

Someone mentioned earlier in the thread, that this crash seemed like the one where the Air New Zealand plane was coming off lease and was being checked, before being returned to Air New Zealand from a German airline. It crashed into the Mediterranean, because both angle of attack sensors froze due to water getting in them, when the plane was pressure washed instead of dusted off. They worked fine at first, then froze at altitude. The computer didn't have the right inputs and didn't realize anything was wrong, and the pilot wasn't able to figure out the problem and take over from the computer in time, because everything happened so quickly. That was in good weather. This Air Asia crash, if it's similar to the Air New Zealand crash, was in bad weather making diagnosis and recovery even harder, so even with the best pilots, they may not have had a chance to recover. All their effort had to go to working the problem, so that may explain why ATC couldn't get them on the radio, even though they still saw them on radar for little while.

woora

the title of the forum is PROFESSIONAL PILOTS...etc

granted a commercial pilot license would qualify too, forgive me comm

do you earn your living as a pilot? if not, at least state it in the body of your post...I won't take the time to look up your profile.

location of tail
 

Translation of some reports regarding the exact location of the tail are here

AirAsia Tail Location Mystery: Solved?

It is suggested that it is at

-03° 38′ 39″ 109° 43′ 43″ (degrees minutes seconds)

This is about 2.5nm South East of the last SSR/ADS-B location

The color looks right, so is it what they are looking for?

http://i57.tinypic.com/2dmfi49.jpg

A nice chronology of events mapped out on 3D Google Earth. Not sure how accurate it is, but helps to put things into some perspective.

https://pbs.twimg.com/media/B64StelCIAAeoRp.jpg

Source: Twitter

The pings from the blackbox have been detected according to this article.

Here's a summary of all the information I've been able to glean about search locations:


Asia Air LRP ----> from a graphic released by the Indonesians
52.9 miles from RAFIS ----> Training wheels post # 1421
TAIL ----> Suggested by MGS Ship Geo Survey
tail ----> Suggested by Jeff Wise
Blue suitcase ----> From a picture of Debris released by the Indonesians
FR24 LRP 23:12:37 ----> ADS-B Last reported position
sunken boat ----> a finding by sidescan sonar


http://i.imgur.com/W4WKF00.jpg

New digital units are often combined units. Both FDR and CVR functions in one 'box'.

Flight recorder - Wikipedia, the free encyclopedia

Santoso Sayogo, an investigator at the Indonesian National Transportation Safety Committee has stated to the media that he has received a report from the field, that their SAR people are now picking up pings from the flight data recorder - and that the pings are some distance from the location of the tail, thus indicating the FDR became detached during the crash.

Black box not in the tail
 

As per video below, it seems that the black box was separated from tail "a few hundred meters downstream"
BBC News - AirAsia QZ8501: 'Divers in water trying to raise plane'

I wonder exactly what "detected 300 metres from" means. but anyway... good news if they have located them!

AirAsia crash: 'ping' signals from black box detected

Coagie:
While the weather situation was much worse for the Air Asia crash than the Air New Zealand crash, the altitude situation was much worse for the Air New Zealand crash: the Air New Zealand pilot did the acceptance tests at low altitude so there was very little time and distance to attempt recovery--while the Air Asia was at high altitude and had a significant amount of time and distance to attempt recovery.


http://www.antaranews.com/en/news/97...-victims-found

Originally Post by onetrack http://www.pprune.org/images/buttons/viewpost.gif
Santoso Sayogo.....he has received a report.....that the pings are some distance from the location of the tail, thus indicating the FDR became detached during the crash.

Interesting to know how distant. AF447 (below) had ~10,000' for currents to nudge debris yet the FDR module was within maybe 150' of the APU, THS, and CVR (though farther from the FDR chassis). Air Aisa's search depth is only ~100'. The FDR would not have flowed with current, though the tail might have depending on what we find it looks like now. However the distance between FDR and tail, and the heading between, calculated together with the current should be telling about what part touched down first, and what forward speed might have caused the distance.

AF447: Map of the debris field - Flight International

Don't misconstrue. I use AF447 ONLY because despite the huge difference in circumstances between the two, debris field maps don't grow on trees, especially accidents that generate huge interest and lots of valuable images for a hungry media, so there aren't a lot to choose from. And comparisons between the two can be as instructive for their dissimilarities as their similarities.

An updraft will not in itself reduce airspeed. Updrafts add energy, not reduce it. The first reaction by the autopilot (or PF) would be to try to maintain altitude by putting forward pressure on the stick. This will in effect increase the speed because of the updraft wind vector (and no, I do not subscribe to the previously mentioned theory that the wing will get hit before the tail, so the nose will rise markedly; it all happens too fast for that). Next, the power will come off (ATS) the crew may pull the SB out to keep the speed under control or, as I understand in an Airbus, if an overspeed is going to occur, the AP will raise the nose. The only real problem with convective activity (if the aeroplane doesn't fall apart flying into the updraft in the first place) is the subsequent possible downdraft encounter out the other side. Perhaps with the nose climbing (Airbus) and speed now reducing (no updraft, or potentially a downdraft)... it should still be controllable with full forward stick and full power (which would already be set by the ATS as the speed is below target).

I do not buy the claimed 9000ft/min ROC and massive speed reduction was caused only by an updraft. And that would assume they were actually in a cell. Updrafts are essentially overshoot shear scenarios, and you don't stall in those scenarios.

Although we don't know exactly what it was based on - because we were never told what radar had reported this, but in the first few days all the media was reporting that they had been told that the GS for QZ8501 was very low.

Now that we have the ADS-B information we can be sure this low groundspeed couldn't have come from secondary radar so it had to have come from a military primary radar. Or it might have been bogus information, but it has never been retracted afik.


Edit: After a bit of research I've come to the conclusion that the entire basis for the low speed assumptions for QZ8501 have been based on that radar plot which was released on day one of this event and had the numbers 363 which was taken to be the altitude and the number 353 which was taken to be the speed (IAS at FL 36.0).

That's not very solid evidence, that "radar plot" may have been composed for a news release quickly - it may have been mostly eye candy.

small correction, but important ...
 

It was not an Air New Zealand captain or pilot in the seat for the Perpignan crash. He was a German pilot for the safety checks to return the plane to Air New Zealand. Very sad circumstance ... and nothing the crew could do to save themselves.

https://www.youtube.com/watch?v=jJrK-1qr59M

Thank you Bloggs.

This whole "updraft" discussion is completely baseless on the known information.

tcas
 

In ordinary circumstances, TCAS can be very useful for awareness of other aircraft.

If pilots have their hands full controlling aircraft in severe conditions or possibly eyeball bounce, things become more difficult. I spent a lot of effort avoiding this stuff. Experienced plus and minus 3000 ft in turbulence and iceing with seriously impaired vision in an embedded CB in my early days. There was no such thing as TCAS, but if there had been, it would have been useless, due poor vision.

Tidal currents
 

The tidal streams seem to have quite a range in the search area, something like a 2-3m range. We're just past Springs or full moon so they should be easing now with neaps on the 13th, the best conditions for diving there.

I can assure you catergorically that radar plot I posted on page 1 came from a well respected senior ATC controller at Jakarta whom I know personally.

Propduffer
Not sure anyone would be "smiling ear to ear" faced with the still unknown situation QZ8501 was in...

Furthermore I don't believe the Captain lacked in flying ability...I feel his experience flying fighter jets would attest to this...

Blind speculation is just that at this point... for all we know the Captain went to the toilet and all hell broke loose...it has happened before...

When they find the nose section, it could well look like this:

Oh, Hail! | Aero-News Network

Which may also explain the "no comms" due possibly to shredded antennae.

It may also explain the low GS due possibly to flame outs.

Anyone who has a lot of experience in SE Asia has noticed a large increase in "newbies" who believe the glossy brochures and management cost mantra that modern a/c can weather any storm.

For those who have been in one and lived to tell the tale, they never, ever do it a second time.

If the CVR has been located, we shall all know soon enough.

RIP to all those innocent souls:(