Continental TurboProp crash inbound for Buffalo

[q100]

Given that a stall beginning at 125 Kts is entirely consistent with a 105 Kt stall speed and a 1.42 g load causing an accelerated stall (by my math, at just over 124 kts) it does not sound like ice was a factor. That's probably why they're looking at the crew's actions...

What really ought to be looked at, and it is hinted at, is the way the FAA insists upon stalls being demonstrated in training (full power, minimal or no altitude loss) - interpreted by most check airmen it seems as "hold your pitch attitude." Trying to do that against a stick pusher could be really interesting....

Primary training I think gets it right - first priority is to reduce angle of attack, while at the same time using full power (which also, by increasing speed, usually helps reduce AofA) to minimize altitude loss. That is just my opinion. I usually started new students out by recovering without use of power, then working up to worrying about minimal altitude loss.

[Hiflyer1757]

Is this related

First the NTSB wants to review several items but one that caught my eye was a review of sterile cockpit rules. Further reading of the NTSB shows that the FDR/MTC/Training/ATC and other were discussed in this release but nothing was said about the CVR.

[Pugilistic Animus]

Lomapaseo

Where did you obtain that photo?!!!
and is that THE photo?
sorry for the thread creep,..been following all these accidents from the begining

PA

[Willit Run]

"FDR data further
indicate that when the stick shaker activated, there was a
25-pound pull force on the control column, followed by an up
elevator deflection and increase in pitch, angle of attack."

Kind of wondering why the "pull" on the control column, and not a "push"??
When a stick shaker goes off, that should indicate that anymore pitch UP would exacerbate the situation.

It'll be interesting.

[News Shooter]

NTSB now says ice was NOT the Cause

I know the details of the report were posted earlier today, but the media just picked up on it

Ice Ruled Out as Culprit In Feb. Plane Crash


Still Hunting for Clues, NTSB Says Icing Had 'Minimal Impact' on Buffalo Tragedy


By MATT HOSFORD and KATE BARRETT
March 25, 2009



Investigators examining multiple plane crashes this year have their hands full, but today they announced progress toward learning what caused last month's fatal plane crash near Buffalo, N.Y.

In this file photo, a plane burns after it crashed into a house in Clarence Center, N.Y., in...
In this file photo, a plane burns after it crashed into a house in Clarence Center, N.Y., in February. The National Transportation Safety Board said that ice was likely not the cause of the Feb. 12 crash of Continental Airlines Flight 3407, despite early media reports identifying ice as a potential culprit.
(David Duprey/AP Photo)

The National Transportation Safety Board said that ice was likely not the cause of the Feb. 12 crash, despite early media reports identifying ice as a potential culprit. The safety board today said it would continue to look at the pilot's experience and training.
The NTSB said that while there was some ice present, "the airplane continued to respond as expected to flight control inputs throughout the accident flight."
The safety board added that "Preliminary airplane performance modeling and simulation efforts indicate that icing had a minimal impact on the stall speed of the airplane."
Fifty people died when the Continental Express commuter plane crashed a few miles short of the runway.
ABC News learned in mid-February that the pilot on the Buffalo flight may have put the plane into its deadly plunge.
A source close to the investigation said information from the flight data recorder indicated that the pilot's control column, essentially the device used to steer the plane, moved sharply backward, pitching the nose of the turboprop upward.
Investigators said they were surprised a pilot would take that action and wanted to make sure there wasn't some other explanation for the movement of the plane's controls.
Federal investigators said today that when the stick was pulled back, the airflow, or lift, over the top of the wing was likely lost. Losing lift over a wing can cause an aircraft to stall.
"If you think you're stalling, you don't pull, you push," ABC News' aviation consultant John Nance said in mid-February.
It can be exceedingly difficult to recover from a stall like the one experienced in the Buffalo crash and, in this case, the crew had only 1,600 to 1,800 feet to do so before the plane hit the ground.
Shortly after the crash, investigators said they were also looking carefully at the training the pilot received, as they do with any accident. The captain, Marvin Renslow, 47, was new to the Canadian-made Bombardier Dash 8 Q400, with 110 hours at the controls flying passengers.
On Feb. 18, Colgan Air, which operated the flight for Continental, defended the pilot's experience and stressed confidence in its operations.
"Capt. Renslow had 3,379 total hours of flight experience and was Airline Transport Pilot rated, which is the highest level of certification available," read a statement from Colgan Air, which operated the flight for Continental Feb. 18. "That rating, combined with 172 hours of formal training on the Q400 aircraft, qualified him fully in accordance with all applicable federal aviation regulations."
Investigators also said today they have reviewed airplane maintenance records and have not uncovered any "significant findings." Toxicology reports also found no alcohol or illicit drugs in the flight crew.

[BreezyDC]

Public Hearing

Can anybody here explain me what this "public hearing" means?

Sounds like they are on the "pilot-thing", 4 out of 6 points go to crew/company

Since this is the first major fatal US accident in a couple years, not inappropriate to hold a public hearing. As NPR reported (on a different NTSB decision): "The NTSB holds public hearings for several reasons - to educate the public, make the board's investigation transparent and to gather information from outside experts. The investigative staff recommends whether to hold one and the board votes on their recommendation."

Whether or not they hold the pilots and company responsible, most likely being held due to the seriousness of the accident, and perhaps they want to make some political points about the FAA, icing, what have you....

Or maybe they just want to be transparent and minimize speculation on this forum.

[lomapaseo]

Pugilistic Animus

Where did you obtain that photo?!!!
and is that THE photo?
sorry for the thread creep,..been following all these accidents from the begining

PA

Typical thread creep photo where the source post was deleted

nothing to now link it with this thread so time to move on

[barit1]

More speculation:

Is it possible the stick pusher was wired backwards?

If so, it wouldn't be the first time a system had wires crossed.

Does the Dash 8 checklist include a stick pusher check?

[FlyingTinCans]

Is it possible the stick pusher was wired backwards?

More likely is that the autopilot had trimed aft to maintain the altitude while the speed was decaying, and once the stick pusher had released the pilots were presented with an out-of-trim nose up pitch aircraft.

I know we are all taught stall recovery, however, in my training we were told to not trim below a certain speed to stop the above from happening when you recover from it.

[Tu.114]

In my company, the stick pusher is not checked explicitly; just the Push off -PB is checked to be not latched in in each preflight and before the first flight of the day, a Stall warning system test is executed.

Wired backwards - in a sense that the stick pusher works as stick puller in the case of a stall? Rather unlikely. In case both Stall protection modules agree, the stick pusher is triggered electrically, but the actuation is by hydraulics.

[Mad (Flt) Scientist]

Originally Posted by Willit Run

"FDR data further
indicate that when the stick shaker activated, there was a
25-pound pull force on the control column, followed by an up
elevator deflection and increase in pitch, angle of attack."

Kind of wondering why the "pull" on the control column, and not a "push"??
When a stick shaker goes off, that should indicate that anymore pitch UP would exacerbate the situation.

It'll be interesting.

it's not uncommon for column force instrumentation (at least on test a/c) to register a "pull force" when a stick pusher fires, because it's practically impossible to instantly release the column, and so the pilot's hands, inevitably, resist the push, which will be picked up as an apparent pull force, opposing/slowing the pusher.

It's not clear from the quote about the FDR whether it's an instantaneous pull or a sustained pull; the former would be consistent with a puilot briefly re4sisting the push and then allowing it to do its job, the latter would indicate sustained resistance to the pusher.

It's also very difficult with the frequency of most FDR control force parameters to pick up a true instantaneous force - so the actual force may have been higher (a similar issue is routinely encountered when trying to assess how "hard" a "hard landing" actually was, for example)

Given that pusher systems typically are designed only to apply force in one sense, mechanically, and to release in the other, it'd take a considerable amount of ingenuity to rig one backwards and not notice. Certainly some pusher equipped a/c have pusher tests where it would be extremely obvious that this had been done; I don't know if the dash 8 is one of those, though.

Edit: apologies, I answered that as if it were "pusher" but as pointed out below, the reference is to "shaker".

[AerocatS2A]

Originally Posted by FlyingTinCans

More likely is that the autopilot had trimed aft to maintain the altitude while the speed was decaying, and once the stick pusher had released the pilots were presented with an out-of-trim nose up pitch aircraft.

Probably not. The report states there was a 25 pound pull force on the column. That means something or someone was physically pulling the control column. Also, the pull occurs after the stick shaker, not the stick pusher.

[PapaThreeCee]

NTSB Report Question

The excerpt from the NTSB Report posted above briefly mentions that the stick pusher is an integral part of the aircraft's stall warning system, but all subsequent references to the control column being pulled aft say that action occurred at "stick shaker."

Are we supposed to interpret the NTSB's use of the term "stick shaker" to also mean "stick pusher?" Why don't they make a distinction between the two . . . unless - perhaps - the pull happened at "stick shaker" and NOT at "stick pusher?" I believe that is an important distinction.

[AerocatS2A]

Yes, no mention is made of the stick pusher activating, but it also says there were no known malfunctions, so the pusher must have gone at some point.

[TheShadow]

Thick Investigators?

Can the DFDR discriminate between a pull force and a "back-trimmed in" autopilot auto-trim induced resultant force? The DFDR may have logged the nett force resulting from the pilot pushing against the yoke's nose-up out-of-trim force.
From the article circulating:
"The NTSB said a stall warning device known as a "stick shaker" appears to have behaved properly, activating when the plane's speed dropped to 130 knots (150 mph). At that point, however, "there was a 25-pound pull force on the control column," pulling the plane upward, and data suggests there was a "likely separation of the airflow over the wing" -- meaning the plane had stalled."
*
They don't seem to be able to get it into their heads that the aircraft had been already progressively (and totally) back-trimmed (during its unmonitored deceleration towards the stall) by the autopilot's elevator auto-trim into a zoom-climb condition. Add the pitch-up effect of max power and you have an aircraft PRIMED to pitch up suddenly. The pilot would have added max power and instantly faced having to fight, with forward yoke pressure, a massive nose-up pitching moment.
Forget tail-plane stall. Think more in terms of the threat posed by partial automation. An autopilot that could be set to level off from a descent - but no auto-throttle to add power. All it took was the pilots to become momentarily distracted and forget to add power to maintain the level speed.
*
Partial automation is a deadly trap i.e. an autopilot that levels off and auto-trims the elevator back all the way into a stall. It's very similar to the 737 crash in Amsterdam where the auto-throttle was supposed to add power - but their autothrottle had been disabled by the radar altimeter "spiking" to 8ft and thereby*replicating what normally happens in the landing flare at 10 feet above the bitumen. That radar altimeter flaw is a known fault by the way (and had even happened before on that same airframe).. The pilots in the 737 accident responded in a very similar manner i.e, max power once the stick-shaker/stick-pusher warning annunciated and alerted them. However they (he actually, because the other pilot wouldn't have realized what the problem was) would have then been fighting a huge rearward pressure on the yoke, caused by the full back elevator trim and the pitch-up effect at low speed of underwing-mounted engine thrust. In both accidents an unrecoverable low altitude stall resulted.
*
The only essential difference between the two accidents is that the Dash8 doesn't have an autothrottle...... but that quintessential and vital fact can be overlooked by distracted and fatigued pilots heads down re-programming the FMS keypad during an approach.
*
So it's pilot error very ably augmented by a phenomena destined to be known as partial (impartial?) automation (in the Dash8 case). In the 737's case it's the lack of an adequate deceleratory alerting system. The very rapid reduction in speed of a configured/configuring aircraft - once an autopilot captures a dialled-up height - trumps the alerting threshold value of a stick-shaker/stick-pusher. Why? Mainly because the stall recovery will be severely complicated by the pilot suddenly having to wrestle with a 25 lb zoom-climbing stick-force gradient.
*
In both accidents the pilots were unable to avoid a full-blown nose-high stall at low-level and the ensuing deadly autorotative wing-drop. It's possibly the deadliest surprise trap you could ever spring upon a pilot at low-level, particularly if he's still in IMC (or is flung back into cloud by the zoom-climb). It'd be totally disorienting. Is it going to cost Bombardier and Boeing? Good question. Past experience of such inbuilt technical quirks (eg Helios 737 and lack of attitude indicator twinning, center fuel-tank inerting, MD-11 flawed smoke checklist etc) would suggest that they will introduce a flight manual warning and stop short of any modifications. Why? Introducing a modification, even an additional warning system, would be a tacit admission of a pre-existing deficiency that would make them very vulnerable to litigation.
*
And so we are stuck once again in that round-robin of immoral rectitude that makes an expected call of "pilot error" - when it patently and obviously (to the cognoscenti)*really isn't.
*

[Clandestino]

I have 2600 hrs in ATR (no autothrottle) and about a dozen in A320 with autothrust MELed inop.The fact that I'm posting here somewhat contradicts claims that aeroplanes with autopilot but without autothrottle are death-traps.

[protectthehornet]

I think I asked about the meds the pilot may have been using, and I see that he was taking a blood pressure medicine (though FAA approved). Perhaps more study of medicines used by pilots is in order.

Sadly too , there is simulator training which makes a pilot change whatever he has learned in small planes...that is to push forward on the stick to break a stall...sacrificing altitude to regain lift. The modern method is to hold altitude at all costs, while waiting for engine power to help overcome the stalled condition .

To the man who doesn't think that autopilot equipped planes without autothrottles are not death traps...you are right of course. but it does take a pilot who knows what he is doing AND ACTUALLY DOES IT.

[ACMS]

No, the "modern" method you use depends on how much height you have available:

A lot of height and you push forward to un stall the wing asap ( traditional )

No height available and you milk it to minimize ht loss and thus avoid the ground. ( by milk it I mean lower the nose on a tad while the power comes on and then fly it out gently )

The Boeing QRH says it better than me:--

Advance the thrust levers to maximum thrust, Smoothly adjust the pitch attitude to avoid ground contact or obstacles. Level the wings (do not change flaps or landing gear configuration.) Retract the speedbrakes.
When ground contact is no longer a factor:
Adjust the pitch attitude to accelerate while minimizing altitude loss.
Return to a speed appropriate for the configuration.

[Flight Safety]

From the NTSB statement:

The FDR data indicates that the stick shaker activated at 130 knots, which is consistent with the de-ice system being engaged. FDR data further indicate that when the stick shaker activated, there was a 25-pound pull force on the control column, followed by an up elevator deflection and increase in pitch, angle of attack, and Gs. The data indicate a likely separation of the airflow over the wing and ensuing roll two seconds after the stick shaker activated while the aircraft was slowing through 125 knots and while at a flight load of 1.42 Gs.

Clearly, the aircraft was pitched up right after the stick shaker activated. This was most likely caused by the pilot.

A preliminary examination of the airplane systems has revealed no indication of pre-impact system failures or anomalies.

I've stated previously that perhaps this previous Saab 340 pilot thought he was experiencing a tailplane stall, because the stick shaker activated at about 10 degrees flap, as the flaps were transiting from 5 degrees to 15 degrees (after 15 degrees flap was selected). It's unfortunate (if the pilot was thinking about tailplane stall) that the airspeed decayed to the stick shaker warning WHILE the flaps were in transit. We know the flaps were immediately retracked after this, never reaching 15 degrees, as previously stated by the NTSB. This also indicates to me "tailplane stall" in the mind of the pilot, since flap changes can cause a tailplane stall.

The CVR hopefully can reveal more about this possibility, in light of the NTSB's desire to discuss sterile cockpit rules in the public hearings. Fatigue could also explain why a stick shaker warning could be interpreted as "tailplane stall" in the pilot's mind, as the NTSB want to discuss fatigue as well.

[chuks]

Simulator training...

Stall recovery training in the simulator isn't done to a full-breaking stall usually, is it?

From what I remember about the Dornier 328 (the only large airplane I have had simulator training on) the simulator training has you responding to the stick-shaker to initiate recovery. That would be the PF calling "Stall!", going to TOGA power and then making an appropriate stall recovery, when the call would be "Stall recovery complete."

It is pretty much a non-event, giving that if you do it right you never enter the full-stall regime. (In fact, I don't think the sim is required to model that with 100% fidelity. Low-speed handling in the 328 sim was pretty woolly, much sloppier than the real aircraft.)

A properly-flown stall recovery should see you losing very little if any altitude. Even at altitude there's no real question of "pushing" the nose down "to break the stall." You are responding to the stick-shaker, which is a stall warning occurring before the stall itself so that there is no stall to break. Really, you are just getting away from a pre-stall condition. For a straight-ahead power-off stall this means just going to idle, raising the nose enought to get a 1 knot/second speed decay and waiting for the shaker. Putting the nose on the horizon with TOGA power usually sees a smooth acceleration out of the pre-stall regime with little or no descent.

If you get the pusher then that means you have already had the shaker. The shaker, though, is your first cue to start the stall recovery. That is what it is there for.

If you overpower the pusher then, yes, the aircraft will enter the full-stall regime. For one thing, you have to be able to overpower the pusher as a safety measure in case you get a false pusher actuation, as sometimes happens. You would not want an aircraft that could put itself into an unrecoverable dive just after takeoff or on short final, for instance. But if you choose to overpower that nose-down pusher input when it really is just doing its job, keeping the aircraft from becoming fully-stalled, well...

I think we try to stay away from speaking of "pushing" or "pulling" when we are speaking of how we fly. We want our aircraft to achieve a certain attitude so that we focus on the desired attitude. For instance you should not tell a primary student to "Push the wheel forward to break the stall." Instead you might say, "Put the aircraft in (such-and-such an attitude)." Telling some muscle-man to "Push!" can see your heads hitting the headliner in a Cessna 150!

Here we are getting a description of what happened, a 25-pound pull, but that is not how we should speak of it when flying. I just need to know where I want the airplane relative to the horizon.