OK465

............

RR_NDB

Quote:

CJ@#1314: To me, the suggestion of adding an 'unfamiliar, new' instrument (requiring additional training, too) because, once upon a time, people were incapable of inferring the state of their aircraft from the available data, makes no sense.

Why not to present this (important) info when AoA nears safe limits? Could be triggered by "rate". Warning a fast closing in to a dangerous condition. Requiring immediate action.

Certainly not relevant (and not justifiable) in normal conditions.

Another indicator IMHO should be Real Time info on near simultaneous "failure" of critical (redundant) elements, e.g. Pitot's.

The redundancy implemented in the design was not made to simultaneous failure of it. And the crew should be IMMEDIATELY informed of this unusual condition even before a/c degradation.

Why not? Cost is not an issue. Just a simple SW algorithm.

AFAIK we are still relying in "sub heated" Pitot 's.

Machinbird

Christiaan
Probably not Christiaan. The trusting souls who don't bother to cross check their instrument readings definitely won't need one. The ones who have never been taught how to use one are unlikely to appreciate its value.

However, If the simulator sessions emphasize cross-checking of instrument readings and otherwise exercise the use of an AOA gauge, then there will be a significant proportion of airline pilots who eventually appreciate what AOA information can do for them and they will use it.

infrequentflyer789

I don't think it's red at all, and I think there are a few similar ones in the vicinity.

Same argument could apply to AOA indicator, if they'd had one - would they have believed it pegged at 35deg ?

And the speeds were actually valid again as they were stalling - but did they have any indication sppeds were valid again, and would they have believed the (correct) speeds ?

Then consider, not only was the needle pegged, but it is on a narrow vertical display rather than old style gauge. Does that make it easier or harder to notice the transition (maybe in peripheral vision) ?

And last but not least, instrument displays are no longer anything like single signals going to single gauges, but rather a whole bunch of signals going into a chunk of software and coming out as a bunch of pixels. If some of those signals are so far outside normal flight that you are in a completely untested region, who knows what pixels that software will produce ? If there is a flaw, it could affect more than just VSI. Or put another way, that "needle" may not peg, it might wander off the VSI and corrupt some other part of the display.

What we have in the FDR traces are the input signals to the instruments. If it was steam gauges, I'd be happy to trust that the gauge was showing the same - invoking occam to say that we should look for simpler solutions than a failure of a gauge independent but simultaneous with other problems. The behaviour when the signal goes out of range (hits the stops) is also simple to test and be confident in. For glass / PDF I'm not so sure. Not at all.


Sadly, we'll never know exactly what they were looking at, but I would hope that at the very least the HF investigation is feeding the FDR signals into a sim (or the iron bird) to get as close as we can to what the instruments were showing. If we had video of that here, I have a suspicion it would be a bit more confusing than what we may be assuming from the FDR.

There is also the red/black over/underspeed indication theory that I think has been posted more than once. If it's true, and if I understand it right, it may be a serious user interface design failure.

Linktrained

A " Rate 1 Turn" used to be 3 Degrees per second. For AF447 to have turned 180 degrees in, say, three minutes, would suggest that the aircraft was banked throughout this descent. Would this have averaged more than 10 degrees of bank ?

ChristiaanJ

What else is the "STALL, STALL, STALL!" aural warning? It occurs before the actual stall (as well as supposedly during it, different issue, that).

My suggestion and argument, entirely.

Not necessarily "sub-heated".... but still "sub-qualified".
AFAIK, the Thales AA and AB probes, just like the Goodrich (?) probes, all met the certification requirements. The real problem is that none of the certification requirements fully account for the conditions encountered by AF447, and during other UAS events.
I'm looking at this a bit from the engineering point of view.... "I can give you a better pitot, just tell me how to test it to prove it's 'better' and meets your requirements".
And so far, AFAIK, those environmental conditions, and certification tests (dating from way back) have still not been updated.
The UAS procedures are nothing more than a stopgap and a BandAid.
UAS should no more be possible.....

infrequentflyer789

In normal flight, I'd agree, but for diagnosis and recovery once stalled, is the simple binary warning/shaker (or not) enough ?

If we assume that everyone recovers promptly (and without getting into a worse secondary stall) at approach-to-stall, then again, there would be no need - but recent history shows that that is a fatally bad assumption.

Smilin_Ed

Well, how did they use it in the Concorde? Why was it there?

In carrier operations, it is the primary speed indicator for approach to landing. At approach speeds, it is operating in its most accurate range and precise speed control is essential to a good carrier landing. Every aircraft that I flew, the AoA indicator was calibrated to be "on speed" at 1.3 Vstall in the approach configuration. No matter what your weight, you were at 1.3 Vstall when the AoA indicated "on speed".

AoA is not useful at cruise speeds because the variation of AoA with speed is much smaller than at approach speeds. However, it could have been useful to the crew of AF447 in understanding their situation had they been trained to understand it.

As far as incorporating it into the scan, it is just like any other instrument. In fact, it is an excellent cross check against the airspeed indicator.

jcjeant

Hi,

HazelNuts39
From the CVR extract BEA report N°3 .. the first calls about altitude are :

2 h 13 min 32 PF call out level one hundred
2 h 13 min 36 PF call out Nine thousand feet
And the last (astonishing) call out from the PF is at 4000 feet
2 h 14 min 05 PF Well we need to we are at four thousand feet

RR_NDB

Hi,

IMHO this is RIDICULOUS. Just waiting for going directly from Normal Law to Murphy Law. Certification "principle" is not being properly used. The bureaucrats (of low qualification) are in control?

IMHO, just RIDICULOUS. Airlines and pilots simply victims of bureaucrats.

Who deliver the a/c to them? With approval from who?

The short duration of erratic data in most UAS incidents shows we are near the "required Watts"(*). So they are certainly SUB HEATED.

(*) For most of situations

RR_NDB

Quote:

IFF789@#1318: And last but not least, instrument displays are no longer anything like single signals going to single gauges, but rather a whole bunch of signals going into a chunk of software and coming out as a bunch of pixels. If some of those signals are so far outside normal flight that you are in a completely untested region, who knows what pixels that software will produce ? If there is a flaw, it could affect more than just VSI. Or put another way, that "needle" may not peg, it might wander off the VSI and corrupt some other part of the display.

What we have in the FDR traces are the input signals to the instruments. If it was steam gauges, I'd be happy to trust that the gauge was showing the same - invoking occam to say that we should look for simpler solutions than a failure of a gauge independent but simultaneous with other problems. The behaviour when the signal goes out of range (hits the stops) is also simple to test and be confident in. For glass / PDF I'm not so sure. Not at all.


Sadly, we'll never know exactly what they were looking at, but I would hope that at the very least the HF investigation is feeding the FDR signals into a sim (or the iron bird) to get as close as we can to what the instruments were showing. If we had video of that here, I have a suspicion it would be a bit more confusing than what we may be assuming from the FDR.

FDR in this case may not allow a "complete understanding". Lacks important info inside the loop (a/c-PF)

RetiredF4

Stall-aural warning is an on/off indication, AOA is also a trend indication. Just look at it, see the AOA increase and expect trouble if you dont stop it prior stall range. If STALL sounds, you can check on it how far you have penetrated into unknown territory and how drastic your steps have to be to get out again. And you can crossscheck on it how effective the implemented measures are. You can also identify a false stall warning, which had been present in other cases with UAS and act accordingly.
It is not of interest how helpfull it would be when AOA is above 35°, as it should help to avoid STALL in the first place.

In an air transport aircraft it would be best used as a backup instrument in case of UAS (just fly a fixed AOA value and you are safe, regardless if you are level, climbing or descending) or other situations, where you are operating at the edge of the flight envelope.

The training you would need for that one is nearly none, you just have to be able to read the numbers. The AOA values of interest can be marked on the gauge by colours, those would be cruise, stall, max range, max endurance and others deemed necessary. No magic there.

AOA is a performance indication, and if it is an old analoge one i myself and most fighterpilots where used to, it is higly independent from the rest of the systems and electronic gadgets.

You might have it for years and only register its presence without using it in the daily normal work, but in an abnormal situation it might safe your day.

If it gets implemented, and i´m sure it will, there will be no complaint about it and no problem to make use of it.

rudderrudderrat

Hi RetiredF4

Like this one?
Airbus backs up speed and altitude displays

RetiredF4

I was used to a round one. AOA

The BUSS is again a cocktail of information with different sources and therefore inherent failure and error possibilities.

I would add it completely separate of the other stuff, a stand alone on if you like.

AlphaZuluRomeo

I have no definite answer on "should we have an AoA meter in every liner's cockpit ?"
I don't think "just" adding an AoA meter is a good idea. AF447's crew apparently didn't react on instrumentations they should have known/been trained for (namely: stall warning)...
AoA meter + associated training: why not. I agree that this training is simple.
AoA meter alone: not useful, potentially dangerous.

However:
Huh? How is that?
Stall warning logic is : ring if AoA > limit.
Then a false stall warning implies a false AoA measure IMO.
And a false AoA measure gives a false AoA reading on the AoA meter.
Same source = you cannot cross check.

OK465

Excellent post RetiredF4.

Many attitude display systems incorporate a PLI (pitch limit indicator) that correlates attitude with the onset of the 'stall warning'. This type of display could be utilized in alternate/direct law in conjunction with AOA.

Exactly. Stand alone or incorporated into an existing display thru the OPC (like the 737 NG PFD & HUD), data for AOA & PLI displays are already there.

RetiredF4

First, i dont think that the STALL warning is derived from one or all three AOA vanes and not being run through some gizmo until finally used together with some other inputs like speed, loadfactor. configuration, altitude, you name it.

Therefore i have a more simple device in mind like posted above.

It would be most apreciated, if a backup system would not use the same source as the primary system. Schould not be rocket science.

Lyman

If STALL Training is limited to "Approach to STALL" recovery, an AoA is a must?

grity

but if you show the history of the datapixels on the display, mayby the least 60 sec, like in the datarecorder.... than there is a chance to trust the red line up to 2:11:45 and misstrust it later....

TTex600

I did not keep up with this accident until after the recorders were found and the BEA made it's report this last summer. It is entirely possible that I missed it as I attempted to wade through thousands of posts in six threads, but has the position of the PF's armrest been discussed?