High altitude stall recovery B737

[Check Airman]

Originally Posted by piratepete

Check Airman.Because you might be near the ground and die! Again a stupid statement from you.

Almost exactly 9 years ago (February 12, 2009), 50 people died, in part because a crew attempted the technique you're advocating.

I don't know if you're unfamiliar because you're too new to flying to know of this accident (in which case shame on your instructors), or you're unfamiliar because you stopped flying prior to that.

In either case, the industry has moved on, and we no longer teach people at any stage (private through ATP) to attempt to minimize altitude loss. As an instructor, any student I saw doing that would be sent for re-training.

[binzer]

Originally Posted by piratepete

Vesspot. WHY? Because you might be near the ground and die.Stupid statement.

Oh dear piratepete didn't read the thread title

[vilas]

The reason for change in stall recovery procedure was that the earlier procedure was based on recovery from approach to stall. When a few crashes happened in the US because when the pilots opened thrust the pitch up prevented them from lowering the attitude. So a SAFO was issued and FAA asked the manufacturers to have relook at the procedure. There are some Airbus discussions and conferences which give good understanding of this current procedure. In that one of the test pilot explains it is difficult even for them to identify between approach to stall and real stall. When the emphasis was shifted from preventing loss of height to reducing angle of attack many airlines were uncomfortable and asked what about low altitude stall? So the obvious answer was same procedure. One thing has to be understood that one cannot afford to stall near ground and if you have been that sloppy then some loss of height is inevitable in recovery. You definitely have to reduce the AOA but how soon to recover the flight path will depend on the how close to ground one is and even then if you begin too early it will stall again. The commuter crash was stall near ground. The thrust didn't help, may be they would have still crashed if they would have lowered the nose. In the air every situation is not recoverable. The only way to ensure safety is not to get into those situations.

[mnttech]

On 5/31/16 the FAA's NSP released FSTD #2 which addresses "Full Stall, UPRT, Icing, Crosswind, and Bounced Landing Training Tasks"
https://www.faa.gov/about/initiative...irective-2.pdf
Which adds 7 new areas the airframe/simulator MFG must address:
3. After March 12, 2019, any FSTD being used to obtain credit for full stall training maneuvers in an FAA approved training program must be evaluated and issued additional qualification in accordance with this Directive and the following sections of Appendix A of this Part:
a. Table A1A, General Requirements, Section 2.m. (High Angle of Attack Modeling)
b. Table A1A, General Requirements, Section 3.f. (Stick Pusher System) [where applicable]
c. Table A2A, Objective Testing Requirements, Test 2.a.10 (Stick Pusher Force Calibration)[where applicable]
d. Table A2A, Objective Testing Requirements, Test 2.c.8.a (Stall Characteristics)
e. Table A2A, Objective Testing Requirements, Test 3.f.5 (Characteristic Motion Vibrations – Stall Buffet) [See paragraph 4 of this section for applicability on previously qualified FSTDs]
f. Table A3A, Functions and Subjective Testing Requirements, Test 5.b.1.b. (High Angle of Attack Maneuvers)
g. Attachment 7, Additional Simulator Qualification Requirements for Stall, Upset Prevention and Recovery, and Engine and Airframe Icing Training Tasks (High Angle of Attack Model Evaluation)

This has been an item of interest of the NSP before AF, since before 2009 I have had NSP inspectors ask to take the simulator to 35K and do some stalls. The point I'm hopefully making is that unless the FAA approved simulator has high altitude stalls listed in the SOQ (which should be available to you) the modeling may or maynot be correct.

[misd-agin]

Originally Posted by macdo

Having just done an exercise in a 330 sim which was in some ways to replicate the AF447 incident, the amount of pitch down and altitude loss to unstall the wing, and then recover without inducing a secondary stall, was quite memorable. A few hands worth of forward trim helped.

Makes the posts about pitching down “5 degrees” seem naive or very mis-informed, doesn't it?

[misd-agin]

ZFT - we are in agreement -

[QUOTE=misd-agin;10055151]Some really bad information here. 5 dog nose down might not break the stall. And waiting for x airspeed to pull?How hard are you going to pull? How heavy are you? How high are you? Or does any of that aerodynamics and physics stuff matter?

Simulators don’t have post stall AOA fidelity. That’s the change. A and B have agreed to a generic n/b post stall fidelity model.

You can’t compare current, or especially older, ‘stalls’ in a simulator and pretend they’re the real thing. They’re not.

/QUOTE]

I’m not sure I understand what you are stating here.0

As of now (most) regulations only require datapacks with stall models up to onset of initial buffet or thereabouts.

On March 30, 2016, the FAA published changes to the 14 CFR Part 60 Qualification Performance Standards (QPS) that define updated general, subjective, and objective testing requirements for high angle of attack modeling and the qualification of full stall maneuvers on Level C and Level D FSTDs.

EASA published NPA 2017-13 addressing many changes including advance stall.

Some of the founding members of AUPTRA have conveniently merged UPRT with advanced stall to produce ridiculously high cost aero model add ons for FSTDs

Most changes will be in regulations from 2019?

[Loose rivets]

I've mentioned it before but James Hamilton-Patterson's Empire of the Clouds is a superb read. I've also laid hands on the bigger copy with lovely colour pictures. James, who was kind enough to review the flying in a storm chapter of my novel, really conveys with passion the era that D Davis gave the talks on. Somewhere, he made an extraordinary statement. It followed the D110 crash at Farnborough.

Words to the effect, Back then there was not the litigious society we have today. If a tragedy happened we were expected to just pick up the pieces of our lives and get on with it.

I suppose years of war made us more pragmatic . . . for a while.

[galaxy flyer]

Originally Posted by misd-agin

Makes the posts about pitching down “5 degrees” seem naive or very mis-informed, doesn't it?

I’m guessing on the order of 30* down pitch?

[Vessbot]

Saying a big number is as naive as saying a small number. It depends on how deep the stall is, how long before recovery is initiated, how much thrust there is, how much elevator authority there is...

I'm an American and I learned the expression "how long is a piece of string" from this forum, and it seems to perfectly apply here.

[galaxy flyer]

I was referring to the post above on A330/AF 447 recovery, specifically.

[macdo]

Originally Posted by galaxy flyer

I’m guessing on the order of 30* down pitch?

Around 25, from a well developed stall, and for what seemed like ages until you could apply pitch up successfully. The Youtube video posted earlier was very similar. Add night, turbulence and IMC to make a genuine horror story.

[john_tullamarine]

A few thoughts ..

(a) a lot of the problem derives from older operational approaches to stall recovery. In general, the operational concern was stall near the ground (typically the usual stall turning final trick) where ground contact was a major concern.

(b) unfortunately, the operational folks evidently didn't make a practice of reading what the certification folks had to say and a disjoint arose.

It is useful to have a read of the flight test guide procedures

For heavies

For lighties

(c) likewise it is useful to read what the test folk have to say on the subject .. plenty of threads in PPRuNe, eg Evaluating stall characteristics - best procedure?. In the present thread, one would do well to heed Safetypee's counsel .. he, amongst others in the certification side of the PPRuNe community, has a lot of runs on the board from which to draw when it comes to suggesting this and that.

(d) as has been observed, AF 447 was a bit of an Industry wake up call in respect to stall recovery and led to considerable training changes. This doesn't, necessarily, mean that height loss can be ignored .. but let's keep the concerns appropriate to the inflight circumstances. At day's end, the aim is not to die and one should be playing the risk cards in the best manner to achieve that desirable end goal.

(e) as to what target body angle might be appropriate, that remains a bit hit and miss in the absence of an angle of attack indication, or some other means of deducing that information from what is provided.

[misd-agin]

“How much bank do you think you’ll get if you stall it at altitude?” - guy in the know.

Since he’s asking it must be something significant - “IDK.”

“How about 60-70, to both sides.”

Five degrees nose down wouldn’t have been enough.

[misd-agin]

(e) as to what target body angle might be appropriate, that remains a bit hit and miss in the absence of an angle of attack indication, or some other means of deducing that information from what is provided.


Which is why the whole ‘target pitch attitude of X’ is nonsense. TRI has decided -10 worked. Airplane had an AOA readout. So I pushed the nose ever lower using the AOA - “no. Use -10.” The slightest back pressure, perhaps still less than 1 G, triggered a stick shaker. “I don’t know what happened but it should work.”

New TRI in the fleet, no AOA experience, had come up with his own ‘technique.’ Debrief, and immediate call to fleet manager, knocked that nonsense off.

[galaxy flyer]

Originally Posted by macdo

Around 25, from a well developed stall, and for what seemed like ages until you could apply pitch up successfully. The Youtube video posted earlier was very similar. Add night, turbulence and IMC to make a genuine horror story.

That was my experience in running fighters out of airspeed in the vertical; once it pitches over like plumb bob, it takes awhile to get useful energy to bring the nose up. The high level stall profile in the Global was done in the 40s; same deal long wait with the nose down until reaching about M.74-ish. But that was more like an approach to stall, not fully developed.

You need what’s required to “break” the stall and see the plane start accelerating. AoA indications are very hrlpful here.

[piratepete]

What?

Check Airman.
I really hope you are not a check airman.I am (TRE version for 28 years).The UK CAA was so concerned about this is issue they sent out a SAFETY NOTICE on it a few years back.
If you have no ground contact issue then altitude loss is not the primary concern.If ground contact is a factor then WATCH OUT.You must balance the need for unstalling the wing against hitting the ground.How can you argue against this? Silly and very dangerous.

[Vessbot]

You should check again the comments he was replying to: a pair of unnuanced parrotings of the old dogma solely concerned with altitude loss. If there's any "balance" to be had, he was shifting the discussion toward its proper place (especially in a thread explicitly about high altitude stalls).

Plus, if you don't unstall the wing you're guaranteed to hit the ground. If you do unstall it, you stand a chance of pulling out. At what point does the balance fall in favor of not unstalling the wing? And how many recent accidents have been caused by too aggressive unstall vs. failure to unstall?

[vilas]

Pirate pete

You must balance the need for unstalling the wing against hitting the ground.How can you argue against this? Silly and very dangerous.

The need for unstalling is paramount because that's what is causing loss of control. Perhaps what you meant was need for early recovery of flight path after unstalling against hitting ground. That's quite another thing. Unstalling the wing is the first action of eventual flight path recovery, may be sooner or later. But as I have said earlier if you are guilty of full stall near the ground there are no guarantees. In India in early days of the MIG21, the phenomenon of superstalling of delta wing wasn't understood correctly where once the AOA went past the critical the drag rise was huge. You needed to put the nose down to unstall because power won't do it. With ground rushing up it needed courage to do that and there have been cases when it wasn't done the aircraft has crashed with full after burner on

[piratepete]

Gents.You cannot solely consider the issue of stall recovery from the position of "high altitude".In a comprehensive pilot training module for this very serious issue it is quite important that pilots of modern jet airplanes are trained in both "terrain is a factor" also when it is not.The recovery methods necessarily differ.This can be life or death.

It is extremely important for all instructors to point this out and give demonstration.Many TRIs emphasize that minimum altitude loss is the key to a "correct" recovery.This is true near the ground but is not the sole measure of correct technique.

[Check Airman]

https://www.faa.gov/documentLibrary/...C_120-109A.pdf

From page 7 of AC 120-109A (my bold)

Additionally, recovery profiles that emphasize zero or minimal altitude loss and the immediate advancement of maximum thrust have been eliminated. Recovery procedures now emphasize:
• Disconnecting the autopilot and autothrottle/autothrust systems,
• Reducing the airplane’s AOA immediately,
• Controlling roll after reducing the airplane AOA,
• Managing thrust appropriately, and
• Returning the airplane to the desired flight path.