BOAC

- don't forget that thanks to the a/c design, the "the stick shaker rattling, and the altimeter unwinding" would not have happened on a 737 if it had the same design UNTIL you lowered the nose to recover from the stall.. Pop that into the mental equation.

Octane

Zorin 75,

You're right, I am experiencing 1g due to gravity. It's ok when your feet are on the ground or you're lying in bed.
Go walk off the top of a multistory building and get back to me and let me know what 1g acceleration feels like.........................

netstruggler

Actually, what you're feeling is a 1g acceleration away from the earth.

To an observer, force due to gravity is indistinguishable from force due to acceleration, and what we feel(when we're not falling) is the same as if the earth exerted no gravitational attraction, but we are being accelerated away from it at 1g.

BOAC

Well, if you have not arrived on terra firma by then, once you have achieved 'terminal' velocity (unfortunate choice of words, maybe, but thought to be about 120mph) it will feel just like standing on the ground, but without the weight on your feet -'cos the ground isn't there.................yet. Get it? The '1g acceleration' of which you speak only exists until you have achieved T V. Basic physics.

aerobat77

when we assume you go in a stall ballistic towards mother earth initially you will have 0G - so feel like in space and start to acclerate with 9.81 m/s2 towards the ground. without air you would continue to acclerate - every second you would be 9.81 m/s faster. but in the athmosphere the air starts to be a drag when you are falling towards earth and after a time the gravity equals the drag - you do not continue to acclerate anymore and have 1G again.

Octane

BOAC,

My point exactly. Prior to TV you are accelerating, 9.8m/s to the power of 2. If you were in a vaccum with no drag you would accelerate until you hit the ground. TV occurs because in air, at some point the drag or retarding force will equal the 1g acceleration due to gravity resulting in no further acceleration. i.e. constant velocity from then earthwards until you hit the ground. You will accelerate until TV is attained..

Mr Optimistic

One more time I suppose ! The sensation of weight is actually the reaction to weight, so you feel you weigh something standing on the ground because you feel the reactive force from the ground to your feet balancing out mg. In level cruise ditto through your bum, the source of the force ultimately being the a/c lift via the seat cushion springs and all points in between rather than the elastic stress from the ground. In all cases no net acceleration. In AF 447, once steady downward speed attained, drag force is matching gee so again you would feel the upward force which in this case you might mistake for the consequences of a 1g matching lift.

While the a/c was accelerating downwards there would have been the sensation of reduced weight until tv achieved. Mixed in with the rolling motion and turbulence, not obvious how 'clear' these sensations would have been in terms of discerning the a/c dynamics.

BOAC

It seems that all those 'obsessed' with the 'horrendous 0g plunge' of 447 as it stalled do not understand what happened. The a/c was lifted up to the altitude and pitch angle where its wings could not support its weight. It probably then settled very gently and 'mushed' downwards gathering vertical speed. Look at two parts of the FDR

1) 'Normal acceleration' and
2) 'Vertical speed'

1) hardly showed a divergence from 1g
2) shows a change from Vs=0 (level at 38,000') to 10,000fpm after around 40 seconds. That is 0 to 10,000/60 fps =166fps after 40 seconds. Using basic laws of motion, the acceleration works out at 166/45fps/s = 4.15fps/s. Since '1g' is 32fps/s you have a change of around 1/8th of a g during the 'acceleration' downwards. Barely noticeable in amongst everything else that was going on. Less than you probably get walking down stairs..

Can we put this Oozlum back in its cage now please?.

renard

Carrying on from slickster and others, I don't think I could hold my control column full aft for 3 minutes - I would runout of steam!

I also reckon that my memory would say "Ah this what you do when you want to stall the aircraft"

Lyman

#489

Along with the nonexistent drop of the nose, the lack of buffet ("What was that?" - who knows, w/o the CVR), the gentle transition to 10k down added to the confusion. Rather, it Subtracted from the understanding.

What's left, the STALL/CRICKET? Known to be unreliable, where does that leave the crew? Exactly. Right where they would remain until impact, more or less.

Is it down to the inability of the two PNFs to see PF's Stick? Me, if I'm there, I will certainly peep this guy's Stick hand. Who goes into the water without a look at the reason? Attitude? Fine, if present, two out of three know the Stick needs a push.

1. STALL WARN malfunction (Design)

2. Autotrim up without Reliable Airspeed (Design)

3. Stick displacement, Command position, (Design)

4. Back Up Speed sensing

5. Horizon U/A, Unreliable.

These are identified as problems at/after STALL, and they need work.

At AutoFlight Loss, the CLIMB. This is the Cause.

A sufficient amount of evidence tells us there was disagreement/confusion related to the climb, and altitude. This is the critical bit. This, if understood, will spill the mitigations for a fix, imho. Laying it entirely at the feet of the Pilot Handling is neglectful of procedure, and ultimately, SAFETY.

Ultimately, which means too late, the failures will be addressed.

In reality, all the important problems happened prior to the PF taking control.

Arguably, with Goodrich Probes, there truly could have been Zig's concierge in SEAT 2, and no harm, no foul.

What is missing is instructive. Like, anything pro pilot.

CONF iture

And also I don't think 2 PNF or 2 Pilots Monitoring would let you hold the control column full aft for 3 minutes.

Sidestick is a sure way to waste valuable information in a multi crew operation.

Lyman

I am certain it was not intended, but in hind sight, cloistered stick is a nifty way to prepare the groundwork for acceptance of SINGLE PILOT.

Bit of a high price to pay for pre-emptive marketing of a bad idea.

ChristiaanJ

Thanks for finally 'coming out', bearfoil, as being the lawyer for Goodrich.

The Goodrich probes were certified (do you undestand the notion?) to the same standards (do you know about certification standards?) as the Thales probes.

The problem is with the certification standards....
The UAS procedures are only a stop-gap and a Band-Aid, not a solution. UAS should not happen.

Back to yet another hamsterwheel......

CJ

Lyman

Yes, ChristiaanJ, and No.

Who is the Attorney? You mention Certs as though they are culpable in and of themselves for the Thales failures. Thales had the bad rep, certs or no. You parse like a lawyer.

Since no requirement existed for surpassing the certs, (Goodrich, but arguably), Thales gets a pass? They were id'ed as problematic, but they met cert, so they can remain until the next fatal?

Unknown Fuel Characteristics caused a T7 Hull Loss? NO. Neither did the certs cause 447 to extinguish. Poor position, find another.

westinghouse

Does anyone know what the severity of the turbulence they encountered in the thunderstorm cell?

ChristiaanJ

In a way, yes.
UAS occurred on numerous occasions prior to AF447,yet nothing was done by the certifying authorities to update/revise the standards.

As an engineer, no, I have never had to certify pitot probes... it wasn't my field.
But I had to do EMI/EMC certification, again against existng standards. If anything looked marginal, or dodgy, we looked into it, and solved it... or accepted it, if it did meet the standards. We were not there to rewrite the standards!

Nope, and your argument is feeble.
UAS (and inadequate standards) was recognised as being a problem, and the certifying authorities should have dealt with revising the standards far earlier, not letting the problem fester until a crash occurred.

Oh come. Some of your 'positions' are far poorer. Let's not go there.......

CJ

SLFinAZ

The PM was acutely aware of the planes attitude from the beginning. The CVR has multiple mentions of urgent "requests" to get the nose down. Combine this with the sharp initial climb and I fail to see how the PM was unaware of the cause and effect...he would/should have been very aware that the aircraft stalled.

I think that the airplane cockpit configuration made it much more difficult for him to actually know what SS inputs the PF was making. As events progressed I think this played into his state of confusion since the PF's actual inputs were not consistent with his verbal comments/replies. By the time the captain returned to the flight deck the PM's state of confusion had reached a point he was unable to
communicate with any real clarity....however it is probably reasonable to assume that the PM needed to intervene early in the sequence (which he tried to do) to enable recovery.

At the end of the day the Captains decision to place the least qualified officer on the flight deck "in command" was the critical hole in the cheese (in combination with the CRM deficiencies that precluded the PM from assuming control).

glad rag

BOAC

- here comes that damn bird again. Read the report? Less than 'light' - oh hell, to save you the bother, try page 27. After all, it is in the PUBLIC domain - that's you! Not forgetting it has been on the various threads here over and over again.

Do people actually get a kick out of this?

vovachan

What stopped the CPT from getting at the controls himself?