Buffalo Q400 crash

On May 13, 2:14*pm, Ron Garret wrote:
In article
,



*bod43 wrote:
On 13 May, 12:57, Robert Moore wrote:
James Robinson *wrote

The drop in airspeed was unnoticed, and the stall seemed
to catch them completely by surprise.

I wonder what the stall warning was doing all of this time?

Bob Moore

It appears that it was the stall warning (stick shaker) that the
captain (pilot flying) reacted to.

The reaction was to immediately pull back pretty hard
quickly precipitating an actual stall. 80% power was also
selected immediately. The stick was held back pretty much
until impact.

This boggles my mind. *I'm just a PP but throughout my training I've had
it drilled in to me to lower the nose on an impending stall. *How can
any pilot not know that, let alone one who is getting paid to fly
passengers?

It may boggle the mind of a PP like you (or me for that matter) who
seldom or never flies in icing conditions. However in icing
conditions a tail stall is possible, and the recovery from that is
exactly what this flight crew did. Yes, I know the Q400 is alleged
not to be suspectible to this but the captain had just come from a
type that is, and the FO spent a good part of the five minutes before
the crash chatting about how she feared icing, had never experienced
it before, and how would she handle it, etc. So then after chatting
and worrying about icing, they got something that felt/looked like it
could be an ice-induced tail stall and since it was on their minds
they did the recovery from that. They acted on instinct and it was
the wrong instinct. IMO.

This crew has come in for lots of criticism and I think a lot of it,
especially on their attentiveness and lack of discipline, appears to
be well-deserved, but there comes a point where it just becomes piling
on.

On May 14, 1:03*pm, xyzzy wrote:

This crew has come in for lots of criticism and I think a lot of it,
especially on their attentiveness and lack of discipline, appears to
be well-deserved, but there comes a point where it just becomes piling
on.

Yeah, but it has to pile pretty high and get pretty loud for pretty
long to bring attention to what some might consider the root industry
precipitant/s.
-----

- gpsman

In article
,
xyzzy wrote:

It may boggle the mind of a PP like you (or me for that matter) who
seldom or never flies in icing conditions. However in icing
conditions a tail stall is possible, and the recovery from that is
exactly what this flight crew did. Yes, I know the Q400 is alleged
not to be suspectible to this but the captain had just come from a
type that is, and the FO spent a good part of the five minutes before
the crash chatting about how she feared icing, had never experienced
it before, and how would she handle it, etc. So then after chatting
and worrying about icing, they got something that felt/looked like it
could be an ice-induced tail stall and since it was on their minds
they did the recovery from that. They acted on instinct and it was
the wrong instinct. IMO.

Thanks for the input. However, there is something about what you say
which worries me greatly. You say that pulling back on the stick is the
correct response to a tail stall, the exact opposite of what you do for
a normal stall. Well, if you have a normal stall and react to it like a
tail stall, then you die, as evidenced by what happened here.

Do you also die if you react to a tail stall as though it were a normal
stall? Assuming the answer is "yes", how exactly are you supposed to
handle a situation where you don't know which is which?

You seem to be implying that the answer is "guess" (and please forgive
me if that's not what you meant to imply), which seems to be extremely
dangerous if you're basically flipping a coin to decide whether or not
you get to survive the stall.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

On May 14, 5:53*pm, Mike Ash wrote:
In article
,

*xyzzy wrote:
It may boggle the mind of a PP like you (or me for that matter) who
seldom or never flies in icing conditions. *However in icing
conditions a tail stall is possible, and the recovery from that is
exactly what this flight crew did. Yes, I know *the Q400 is alleged
not to be suspectible to this but the captain had just come from a
type that is, and the FO spent a good part of the five minutes before
the crash chatting about how she feared icing, had never experienced
it before, and how would she handle it, etc. *So then after chatting
and worrying about icing, they got something that felt/looked like it
could be an ice-induced tail stall and since it was on their minds
they did the recovery from that. *They acted on instinct and it was
the wrong instinct. *IMO.

Thanks for the input. However, there is something about what you say
which worries me greatly. You say that pulling back on the stick is the
correct response to a tail stall, the exact opposite of what you do for
a normal stall. Well, if you have a normal stall and react to it like a
tail stall, then you die, as evidenced by what happened here.

Do you also die if you react to a tail stall as though it were a normal
stall? Assuming the answer is "yes", how exactly are you supposed to
handle a situation where you don't know which is which?

You seem to be implying that the answer is "guess" (and please forgive
me if that's not what you meant to imply), which seems to be extremely
dangerous if you're basically flipping a coin to decide whether or not
you get to survive the stall.

The way you recognize a tail stall is that pitch control becomes
abnormal when flaps are extended. Plus knowing that you're in icing
conditions.

Unfortunately that's what happened to the Q400, because coincidently
their airspeed decayed through wing stall speed at the same time flaps
were extended, so in this case they had a perfect storm to fool
themselves on the type of stall

Note, I'm not saying they were totally innocent here because they
aren't, as they should have been on top of their airspeed before it
happened, I'm just saying that internet PPL holders who never fly in
icing conditions have no right to say that "it boogles" the mind or is
inconceivable that the captain would "be so stupid" as to pull back on
the stick when he entered the stall.

In article 7a611b72-866e-4c6a-8dbb-
, says...
On May 14, 5:53*pm, Mike Ash wrote:
In article
,

*xyzzy wrote:
It may boggle the mind of a PP like you (or me for that matter) who
seldom or never flies in icing conditions. *However in icing
conditions a tail stall is possible, and the recovery from that is
exactly what this flight crew did. Yes, I know *the Q400 is alleged
not to be suspectible to this but the captain had just come from a
type that is, and the FO spent a good part of the five minutes before
the crash chatting about how she feared icing, had never experienced
it before, and how would she handle it, etc. *So then after chatting
and worrying about icing, they got something that felt/looked like it
could be an ice-induced tail stall and since it was on their minds
they did the recovery from that. *They acted on instinct and it was
the wrong instinct. *IMO.

Thanks for the input. However, there is something about what you say
which worries me greatly. You say that pulling back on the stick is the
correct response to a tail stall, the exact opposite of what you do for
a normal stall. Well, if you have a normal stall and react to it like a
tail stall, then you die, as evidenced by what happened here.

Do you also die if you react to a tail stall as though it were a normal
stall? Assuming the answer is "yes", how exactly are you supposed to
handle a situation where you don't know which is which?

You seem to be implying that the answer is "guess" (and please forgive
me if that's not what you meant to imply), which seems to be extremely
dangerous if you're basically flipping a coin to decide whether or not
you get to survive the stall.

The way you recognize a tail stall is that pitch control becomes
abnormal when flaps are extended. Plus knowing that you're in icing
conditions.

Unfortunately that's what happened to the Q400, because coincidently
their airspeed decayed through wing stall speed at the same time flaps
were extended, so in this case they had a perfect storm to fool
themselves on the type of stall

Note, I'm not saying they were totally innocent here because they
aren't, as they should have been on top of their airspeed before it
happened, I'm just saying that internet PPL holders who never fly in
icing conditions have no right to say that "it boogles" the mind or is
inconceivable that the captain would "be so stupid" as to pull back on
the stick when he entered the stall.

Well I think it's fair comment - there was no uncommanded pitch *down* -
(if that's what the pilot saw on instruments, then fair enough - but it
clearly isn't).

--
Duncan

In article
,
xyzzy wrote:

The way you recognize a tail stall is that pitch control becomes
abnormal when flaps are extended. Plus knowing that you're in icing
conditions.

This still sounds like a total crapshoot to me. You can lose pitch
control during a regular stall, and icing can precipitate a regular
stall as well. Obviously in this case the signs were interpreted
incorrectly. Surely it's not a case of "heads we live, tails we die"?
There must be some way to tell which kind of stall is happening besides
these indications which clearly weren't correct in this case, isn't
there?

I guess there doesn't *have* to be, but it's kind of scary if there
isn't.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

Mike Ash wrote:

xyzzy wrote:

The way you recognize a tail stall is that pitch control becomes
abnormal when flaps are extended. Plus knowing that you're in icing
conditions.

This still sounds like a total crapshoot to me. You can lose pitch
control during a regular stall, and icing can precipitate a regular
stall as well. Obviously in this case the signs were interpreted
incorrectly. Surely it's not a case of "heads we live, tails we die"?
There must be some way to tell which kind of stall is happening besides
these indications which clearly weren't correct in this case, isn't
there?

I guess there doesn't *have* to be, but it's kind of scary if there
isn't.

When the flaps are extended, and a tailplane stall results, the aircraft
immediately pitches down. There is no stall warning or stick shaker
activation.

In the case of the Buffalo accident, the nose did not drop, but the stick
shaker activated shortly after the flap setting was made. The stick
shaker is fired by low air speed, and is only a warning of impending wing
stall, with some airspeed margin. It is not an indication of tailplane
stall, or of an actual wing stall. Therefore, the correct action when
the stick shaker fired should have been to push the nose down to keep
speed up and reduce AOA. No question.

Further, the Q400 supposedly will never see a tailplane stall in icing,
but the crew may not have known that. The Saabs the captain previously
flew are subject to tailplane stall in icing, and he might have reacted
based on his previous training and apprehension about such stalls.

In article ,
James Robinson wrote:

When the flaps are extended, and a tailplane stall results, the aircraft
immediately pitches down. There is no stall warning or stick shaker
activation.

In the case of the Buffalo accident, the nose did not drop, but the stick
shaker activated shortly after the flap setting was made. The stick
shaker is fired by low air speed, and is only a warning of impending wing
stall, with some airspeed margin. It is not an indication of tailplane
stall, or of an actual wing stall. Therefore, the correct action when
the stick shaker fired should have been to push the nose down to keep
speed up and reduce AOA. No question.

Further, the Q400 supposedly will never see a tailplane stall in icing,
but the crew may not have known that. The Saabs the captain previously
flew are subject to tailplane stall in icing, and he might have reacted
based on his previous training and apprehension about such stalls.

Ah hah, that makes sense. Given that the stick shaker had activated,
they should have known it was a regular stall and performed a regular
recovery. A tail stall would have happened abruptly with no stick
shaker. Is that about right? Makes sense if so.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

Mike Ash wrote:
Ah hah, that makes sense. Given that the stick shaker had activated,
they should have known it was a regular stall and performed a regular
recovery. A tail stall would have happened abruptly with no stick
shaker. Is that about right? Makes sense if so.

The thing though, at least according to the FAA video on tail stall thing
(it's on video.google.com, search for 'Tailplane Icing') it seems that
tail stall also manifests itself by odd pitch feedback on the yoke... I am
really wondering if there is any clear cut way to identify tailplane stall
from main wing stall as easily as you make it sound...

--Sylvain

Mike Ash wrote:

James Robinson wrote:

When the flaps are extended, and a tailplane stall results, the
aircraft immediately pitches down. There is no stall warning or
stick shaker activation.

In the case of the Buffalo accident, the nose did not drop, but the
stick shaker activated shortly after the flap setting was made. The
stick shaker is fired by low air speed, and is only a warning of
impending wing stall, with some airspeed margin. It is not an
indication of tailplane stall, or of an actual wing stall.
Therefore, the correct action when the stick shaker fired should have
been to push the nose down to keep speed up and reduce AOA. No
question.

Further, the Q400 supposedly will never see a tailplane stall in
icing, but the crew may not have known that. The Saabs the captain
previously flew are subject to tailplane stall in icing, and he might
have reacted based on his previous training and apprehension about
such stalls.

Ah hah, that makes sense. Given that the stick shaker had activated,
they should have known it was a regular stall and performed a regular
recovery. A tail stall would have happened abruptly with no stick
shaker. Is that about right? Makes sense if so.

The FDR data shows the following happening in quick sequence:

- Ice warning showing up on display for first time
- Flap handle setting increased
- Stick shaker activated

The flaps had only extended about 1 or 2 degrees when the stick shaker
fired, but was the crew somehow influenced by the ice warning and the
fact that the flaps setting had just been changed? They certainly took
the wrong action in response to the stick shaker. Why?