Basics

I have been more than a little concerned for many years now we are getting away from the basics in stick and rudder skills. For example i came across an advertisement recently for a Piper cub pilot but the candidate needed a collage degree to be eligible to apply for this position. Can anyone here inform me WTF a college degree has anything to do with stick and rudder skills?? I have known young people who were natural pilots and never had to think about control inputs for example. They were able to do it naturally. Now these people I know for a fact have been over looked because of lack of "academic achievement". This is part of the problem we are facing today with the basics.

Now DA with the avionics they use "easy" I think it's termed, require a whole new type rating for an "easy" avionics fit. Where, God give me strength, is the simplicity in that?? Sorry but i call BS on this. We seem not to be flying the air frame anymore, but the automatics. This does and has scared me for a long time now. WTF ever happened to K.I.S.S?

Current effect
 

One's mind keeps returning to how wind and current would affect the parts found so far apart.

Given that the recorders appear to have been dislodged at impact and that they are amongst the densest parts, one would surmise that they sank very near the actual point of impact. Downstream drifting of the rudder and fin is not surprising given their residual buoyancy and I shouldn't be surprised if the elevators wash up on a beach, with or without the apu, near where the nose cone was found.

What I do find surprising, though, is that the recorders were both found "under a wing" which, if the premise of their sinking first is correct, would indicate that part of the wing and main fuselage also sank very rapidly. Perhaps, if still attached to the wing box, dragged down by the weight of the main undercarriage?

The puzzling thing is the cockpit/forward fuselage. Little buoyancy, weighted down by the nose gear and electronic bays, would it not also sink like a stone? And, if so, one'd expect it to be near the main fuselage. I wonder if it's not folded underneath.

Unlikely, it would have been spotted when they raised the fuselage.
(And then dropped it when a rope broke.)

sop monkey

I've never met anyone who was a ''natural pilot''. I've been called a natural pilot by some and I told them I had to study everything twice as much as most. I think the term , ''natural pilot" is wrong to ever use.

College shows that you can train your mind, learn how to learn. And most airline pilots will tell you that stick and rudder skills are not tested on the Oral exam. ;-)

I've known very good pilots who didn't finish college. And I've known some rotten ones with degrees.

The black boxes were obviously found some hundred feet away from the main wreckage. But they were said to be stuck under a "wing" and tangled in other wreckage remains.
Probably the divers misstake the horisontal stabiliser for the wing, so the rest of the rear assembly including the quite heavy APU can be on the spot where the boxes were found.

You have missed it.

Some discussion has postulated a sudden pitch-up on encountering an updraft.

These postulations have been time and time discredited by those who actually understand what happens when entering an updraft - ie the aircraft will pitch DOWN not up and the airspeed will INCREASE not decrease.

Any glider pilot will tell you have to try pretty hard to lose airspeed in an updraft.

The only thing that will result in a sudden gain in altitude and loss in airspeed is a zoom climb, which is caused by the aircraft pitching significantly upwards, as happened to AF447, and as also appears to have happened here.

What we don't know here is whether the significant pitch up was caused by a pilot pulling back on the stick, a mechanical malfunction, a sensor malfunction, or whatever else. Presumably the FDR data will tell us in time. But can we quit with all the updraft speculation please?

Totally agree.
Another side to this is if you are on ILS to RW25 at LAX you will traverse the duty thermal over the car park on short finals. Because you need to maintain a constant G/S, then the extra energy from the thermal means that you gain 5-10kts unless you reduce thrust (in a heavy).

We simply don't know why the pitch up occurred or why it turned left.

We know why he turned left (weather deviation)
Dunno if climb was for the same reason ..........

Unlikely to be a 90 degree deviation and it occurred after the pitch up.

And climb was most likely because he was below optimum for such a short flight.

Turn and Climb Timing
 

Having no idea of the exact Wx that he was facing, I have no idea what his deviation was likely to be. I have no idea why 90 degrees would be more or less likely. However, the radar plots which have been doing the rounds lately show a left turn initiated at 23:16.52 at FL320 and rapid 'climb' starting at 23:17.18 while still at FL 320.

it has been stated many times that his increase in FlL request was denied. It's highly unlikely that he would initiate a unauthorized climb to move up to optimum .

I think it unlikely that it would have been totally an updraft. But if it was the autopilot would maintain altitude until the speed increase approached Vmo/Mmo, then the automatic overspeed protections would raise the nose to control speed. This overides sidestick input from the pilots and MAY trigger a cascade of events ending in a high alpha attitude.

There are other scenarios involving no sensor fault but an unhappy combination of wind change, temperature spike and high vertical speed approaching a higher target altitude which can result in a low energy/high pitch situation.

Writers without Airbus experience should appreciate that the flight control programming is biased towards load relief and structure protection, hence the attitude constraints and the urgency with which overspeeds are "corrected" by the software.

Additionaly, from my own simulator training I suspect (but have not found mention in any manuals) that when a protection gets triggered it stays active until the original condition has been corrected, so that an overspeed protection will overide the stall protection from activating, and vice versa.

As a writer with Airbus experience, i can say that you very accurately described what i criticise since many years! :ok:

Reading what i have enlightened makes a scary story.
In short, the two recent Airbus fatal accidents have shown that whatever the protections wanted to protect (load relief and structure protection) has resulted in the exact opposite!

We can now wait for another lengthy and overcomplicated analysis of what exactly happened at which exact moment, what computer action went wrong and what exactly the crew should have done out of memory to counteract the overwhelmed and misguided program, or .... we can wait for a speedy and effective correction of the programming and design.

My bet is on the earlier in a years time and nothing on the second.
Waiting for the next Bus excursion.

"it has been stated many times that his increase in FlL request was denied. It's highly unlikely that he would initiate a unauthorized climb to move up to optimum ."

He had been cleared to climb from FL320 to FL340 and to await further clearance. He shot through FL340 in the zoom. A 90 degree turn is not a w/x 'deviation'; it would need a PAN call or at least to advise how many degrees. It's normal to state how many degrees L/R, or more usually, the number of miles off track required.

Gretchenfrage, Australopithecus

Just a question from a VFR pilot: It would seem that a safer reaction to overspeed would be to apply speedbrakes/reduce thrust, instead of raising the aircraft's nose and potentially end up in a high-alpha situation. Or am I missing something?

Fresh bid to raise fuselage fails
 

"The Indonesian admiral in charge of operations to recover AirAsia flight QZ8501 has told the BBC the fuselage may be too fragile to be lifted.
Rear Admiral Widodo's comments came after a renewed attempt to raise the wreckage from seabed failed when it kept breaking into pieces."

"a safer reaction to overspeed would be to apply speedbrakes/reduce thrust, instead of raising the aircraft's nose"

In most airliners they are not speedbrakes, but spoilers. Fighters generally have speedbrakes. Spoilers reduce lift as well as increase drag. Hence in airliners they are generally only used on descent when reduction in lift is required and not in level cruise or climb as they reduce stall margins. In the rare event of an overspeed trend in level flight at altitude, you reduce thrust first and only then consider using spoilers. This was not an overspeed situation but a nose up pitch with reducing airspeed.

RifRaf,


On all Boeings the handle to lift the spoilers is called the "Speed Brake lever".

Boeing are also very clear that when correcting overspeeds in cruise, thrust lever to idle positions should be avoided. Thus the preferred method is to apply speed brake first. This protects against slow engine acceleration time at altitude and the risk of overcontrolling speed and inducing a low speed event. That's straight out of the Boeing Flight Crew Training Manual for the B757,767,777,787.


I would try and avoid the sweeping statements.

On Boeing jets, in cruise when one needs to reduce speed, the Speedbrake will be the first option.
Boeing does advice strongly against idling your thrust on cruise. The SPEEDBRAKE is there to accomplish the mission, but do it gently, like everything at altitude.

I seem to remember that AB recommends the same.


By the way...if in doubt: all automatics OFF, go to DIRECT LAW, fly the aircraft raw data like any other aircraft in the world .

First lesson I got during my TR on A320 now 14 years ago...is that still valid? Am I completely misled in this?

Things obviously change.
Interesting, as I only flew 707s and 747s in the early days of autothrottles. Putting out spoilers in cruise then increased thrust if the A/T was still in. So you wound back or disconnected the A/T first. Your point about spool up times is valid, but if you anticipated the target speed you could easily spool up in time and flight idle rpm took spool up times into account. In a severe slowdown you still reduced thrust prior to spoilers but not necessarily to idle depending on the situation. Using spoilers against thrust was a no-no.

Undoubtably with better computation over time this has changed and the deployment of spoilers adjusts the thrust appropriately so that it's not working against the increased drag. You are correct with the Boeing terminology re "speedbrakes", but its mostly a simplified convention. Speedbrakes don't give you 'walkdown' as airline spoilers do? (did).

In most fighters you want to reduce speed quickly without reducing lift and turning performance, so you hang something out that's usually off the fuselage and not the wing. For airline purposes the distinction does not matter as Boeing has decided and "speedbrake" is the simpler generic term. However, it would be interesting to know how much the later Boeings' stall margins are affected by "speedbrake" deployment compared with the early models. No doubt the airbuses are similar to the later Boeings so I accept that speedbrakes are now the first option. I'd also be interested to know how much the lift dumping function relative to the drag increasing function of airliner "speedbrakes" has changed over time. No doubt it varies with the phase of flight whereas earlier it was one size fits all. Thanks for the correction.

The automatics could have thought it was overspeed.

Enter a warm air with a spike up in outside air temperature and the Airbus protections can give you a zoom climb. If that warm air is warm because it is an updraft of significant strength the zoom plus updraft speed could lead to an impressively rapid gain in altitude.

It is what actions are taken by the crew and the subsequent changes in air temperatures, wind changes and downdrafts that will decide what happens to the aircraft. From previous posts on this and AFR447 thread it would appear setting pitch and power for cruise (if the automatics will let you) is the best strategy. And from memory of previous posts this includes stop the trim doing whatever it is doing and manually override it to set what is required, push forward on the stick more than half way to break out of an Alpha prot zoom etc etc., These all appear actions to prevent the aircraft automatics causing issues.

See this report

Page 11 of:
http://www.aaib.gov.uk/cms_resources...%2006-2001.pdf

So what happens at FL380 and 205KIAS/Mach 0.67 15deg nose up, if full thrust is applied and there is compressor stall on the left hand engine? You now have full thrust on the right engine and drag from the left engine. IMC in a grey goldfish bowl with severe turbulence is not a time to be the first pilot to flight test the aircraft's 'spin tolerance' with the aircraft helpfully playing all the various cavalry charges and stall warnings sufficient that you cannot hear each other.

I know on the Boeing 787 direct law can be pilot selected. I thought on the Airbus only the aircraft computers could select direct law not the pilot unless he starts disabling systems to try and force the computers into direct law. Has there been a recent change in Airbus philosophy?

On lifting and evidence...
 

The fragility should not be surpring in general, and is certainly no surprise when you look at even the fuzzy under water pictures.

I have not seen any in-depth official statements on the lifting goal and strategy - what is exactly meant to be achieved. If a poster has some info on it, I would be interested. The goals are probably interesting for many posters, the lifting strategy probably for less.

What one would expect in a 'global attention' case like this is to get some international professional salvage guys in. I have seen foreign aerospace expert involved but not underwater salvage guys. Expertise is expertise, both up and below. Such an approach would not 'lose face'. It is common international practice. These specialists may have a row of proven options in mind.

A few days ago I was thinking ... most shipbuilding having moved to Asia... dont they have a floating/semisubmersible 2nd hand shipdock somewhere, float that to the location, submerse it as required, and get wreckage in without having to lift much, not having to take risks breaking the surface, and even more when lifting, and later more when tying on deck, with these risks repeated in the next land-based phases...? With this option you could collect the lot in situ with less risk. Later tow the dock to shore. De-ballast, and there you are. You even have a longer weather window with this....
For the smaller parts you might also take a few, certainly available, shipping containers (20 or 40x8x8 foot), reinforce them, make a few holes in them, cover the holes with a mesh, sink them on locations, and repeat what I just said for the shipdock. Bonus advantage is, container lifting gear is standard. And it might even help the divers in a number of ways.
The specialists I mentioned would immediately know if this was feasible.

In this case a way shallow water recovery almost seems more of a challenge than much deeper water. There you can get the 'big boys' in ... like the 'dockships' and 'servants' and the lifting barges and big lift semisubs.

Before lifting the tail, there was probably enough opportunity to photograph and video the lot. With the main and wing that is much less certain.

I certainly hope that we do not need evidence from the main and wing ... keeping in mind all the cases where investigators were in the end looking for specific components to be able to close the case.

He had been cleared to FL340 but there was never a response to that clearance. That tells me they never heard it. It also tells me they did not respond because they were already too busy dealing with the problem that caused the aircraft to climb unintentionally. I believe it had to be a mechanical/software issue, a weather related updraft, or a combination of both.

I can't see any other explanation as to why they never responded to the ATC clearance they were given.

The salvage people are never backward in coming forward - and are to be found in Singapore - but there are restrictions on their ability to operate in Indonesia, which would need a high level clearance.

Yes, I wondered if that might be the case/possible?

"He had been cleared to FL340 but there was never a response to that clearance. That tells me they never heard it. It also tells me they did not respond because they were already too busy dealing with the problem that caused the aircraft to climb unintentionally. I believe it had to be a mechanical/software issue, a weather related updraft, or a combination of both.

I can't see any other explanation as to why they never responded to the ATC clearance they were given.He had been cleared to FL340 but there was never a response to that clearance. That tells me they never heard it. It also tells me they did not respond because they were already too busy dealing with the problem that caused the aircraft to climb unintentionally. I believe it had to be a mechanical/software issue, a weather related updraft, or a combination of both.

I can't see any other explanation as to why they never responded to the ATC clearance they were given."

That's a good point and a distinct possibility.

I also agree with Ian W that the zoom climb was probably caused by the system responding to a perceived overspeed for whatever reasons that have been outlined and that the left turn may have been caused by a left eng fail/stall. Alternatively it may have been a left bank to lower the nose, but that assumes that they had gained manual control by then. However, there appears to have been no actual overspeed.

Does this look like the horizontal stabilizer being lifted out of the ocean, only to have it drop back in to the sea due to the rope snapping?

Refer to 19 seconds (0:19) in to the video.

(I know the caption says fuselage, but it looks more like the horizontal stabilizer to me)

Spotted some slats there, so more likely the wing-fuse centre section.

I suppose the idea of preserving forensic evidence has been completely disposed of now? It might have been better to leave the item down there, as is, rather than roll it over the stern of that boat. I really can't see how this can be considered, in any way, proper handling of crash wreckage where the cause is still officially unknown.

There does appear to be, at least, a small portion of the left wing still attached. ???

That's what it looks like. The horizontal stabilizer.
Things get heavy as they are pulled out of the water. That's why you need a net to pull a fish out of the water, without breaking your line, when you catch a big one.
It's a tough recovery, and I'm sure they have to improvise as best they can, as the weather probably limits their ability to have all the equipment they need at the right place at the right time. God bless 'em.

I'm assuming you're not a pilot? Multi-engine aircraft are designed / certified such that above Vmca speed (which is lower than takeoff speed), there will be sufficient control authority even with the most critical engine out and the other engine set to full thrust. So at M0.67 losing an engine (by itself) should not cause a fatal accident.

Now, at high-angle nose up, if the airspeed decays rapidly while conversely the AoA increases rapidly (resulting in a stall), then a one-engine-out situation at that point becomes deadly.

The chord appears to be quite a bit longer than A320 THS, so it must have been the fuselage piece.

Overspeed protection
 

Could somebody explain to a simple engineer how an air temperature "spike" would cause the aircraft to go into an overspeed protection? I've seen this theory posited to explain an automatic pull-up, but I can't see why the aircraft would, either correctly or erroneously, "think" it was overspeeding.

Yes I am aware of the certification of twins and that many of them will reduce maximum available power on a good engine in asymmetric etc.,

But you then go on to agree with what I proposed.

As you are so experienced with A-320 you will know what the minimum safe operating speed is at FL360+. Give the aircraft being 15deg nose up and M0.67/ 205KIAS and autopilot out in AoA law (assuming similar behavior to the quoted report) as you say going asymmetric with a compressor stall one side and full thrust the other could be deadly. It's not only drag - there will be pitch up forces from the live engine and pitch down from the stalled engine. You could also consider what the 'safe control authority' is up in 'coffin corner' at greatly reduced airspeed and what happens if someone is too hasty applying 'full' control authority.

TAS = IAS x sqrt( ISA Density / actual density)

TAS will remain largely over short term (KE) if W/V is unaltered.

Alter OAT alters density (Boyle IIRC?) so requires altered IAS.

Overspeed limits are in IAS terms, so if IAS changes due delta Temp, you can go into an "overspeed".

At altitude, you will be M limited, but again this is Temp dependant.

Clear as mud ;)

It is important in many aircraft to avoid stresses due to shockwaves forming on the aircraft surfaces due to approaching the speed of sound. The speed of sound is dependent on the air pressure _and_ the temperature see Mach Number

So a sudden change up in temperature can convince the automatics that the aircraft is too close to the speed of sound and damaging shockwaves may be forming on the airframe and control surfaces. The automatics then do their best to recover back to below the limiting Mach No. The quickest way to do that is to pull up.


Just as an addition- going too fast and getting shockwaves build on various surfaces can lead to other interesting effects such as control reversals which could lead to dangerous effects.

Yes, it is a pat of the right wing and fuselage
 

@md80fanatic there is a YouTube video shown from the perspective of on the boat. Just before the cable snaps the wreckage is high enough where the letter "C" is visible. This would make the visible portion of what was brought up as the forward fuselage and part of the right wing. No windows were visible also no idea as to the portion below the water. They will be using a crane in their third attempt.

Isn't a, the speed of sound pretty well proportional to the Sq. Root of Abs. Temp?
If so aircraft Mach No. would decrease if Temp suddenly increased?

Have I got my knickers in a twist or am I correct :)

Exactly what I was thinking - an increase in OAT increases the speed of sound, so the aircraft would be even further away from a Mach limit than before. And IAS is dependent on pressure, not temperature, so there'd be no effect on an IAS limit. I'm struggling to see why the aircraft would see any increased airspeed to protect itself from.