Spoilers, no spoilers?

deploy. Next time you are in an airliner watch the aileron/spoileron panels
work together at slower speeds. When the aileron moves up the corresponding
spoileron panel will move with it.

Aren't spoilerons ailerons that can move UP together, killing lift?

Bartek

On Feb 7, 2:46*pm, James Robinson wrote:
Amine wrote:
An Air Canada DC-8 crashed in 1970 because spoilers were deployed
before landing, which "by the book" is a definite no-no (cf. Air
Canada 621 disaster). How come the first officer (with over 5500 hrs
with that type of aircraft) made such a decision to deploy spoilers
while still in the air?

It was accidental.

The spoiler handle could be used to do two things: Lift to arm the
spoilers for automatic deployment when the aircraft landed, or pull out
and down to manually deploy the spoilers. *The FO likely just wanted to
arm them, but inadvertently deployed them instead. *

The handle has since been mechanically interlocked to prevent that
action. (1975 FAA AD)

The irony of that accident was that the Captain had complained to the
company management about the Air Canada procedure at the time. It
required arming the spoilers as part of the prelanding checklist, at
about the same time as the landing gear was lowered. *He felt that
because of the handle design, it was too easy to inadvertently deploy
them at that critical time in flight. *If he was flying, he would
normally ask the FO to wait to deploy them manually only after the
aircraft landed, which was contary to the airline's procedures.

This particular first officer liked to arm the spoilers in the flare, and
the captain agreed to that arrangement. *It appears that the FO both took
action sooner than he should have in the flare, and instead of just
arming them, he also inadvertently deployed them when the aircraft was
still 60 feet in the air.

I think it was higher, but no matter, they tore the airplane in two.
I've read the tapes from this one. Chilling. The co-pilot just kept
saying "sorry Bob, sorry Bob, over and over as the airplane broke
up..




Bertie

"Dudley Henriques" wrote in message ...
Amine wrote:
An Air Canada DC-8 crashed in 1970 because spoilers were deployed
before landing, which "by the book" is a definite no-no (cf. Air
Canada 621 disaster). How come the first officer (with over 5500 hrs
with that type of aircraft) made such a decision to deploy spoilers
while still in the air? What else, when full flaps and idle power
aren't enough, can a pilot use to handle a too high/too fast final
approach if not deploy spoilers?

Go around.


--
Dudley Henriques

My thought exactly!

James Robinson wrote:
Bertie the Bunyip wrote:
I've read the tapes from this one. Chilling. The co-pilot just kept
saying "sorry Bob, sorry Bob, over and over as the airplane broke
up..

"Sorry Pete", actually. (Pete Hamilton) There was no question he was
remorseful.

Yep:

http://aviation-safety.net/investiga.../cvr_ac621.php

On Feb 7, 3:35 pm, Dudley Henriques wrote:

Go around.


Well, let's play the devil's advocate... What if you can't go around?
(E.g. because of engine failure or in a glider). I mean, I understand
why you don't want to deploy spoilers if you're below minimums or if
you're flirting with stall speed. But if you're well above minimums,
with no risk of stalling, I don't see any reason why you shouldn't use
spoilers to bleed the extra momentum/altitude. The only disadvantage
would be that the final approach will be steeper and thereby would not
have the elegance of the perfect glide slope. But that's seems to be
more a matter of taste (and possibly performance) than an actual
safety issue.

After all, the "no-spoiler-in-midair"dogma isn't built in the design
of the pilot interface. If there truly was a physical reason why
spoilers should not come out in the air, it would have been an
engineering requirement to systematically disable their mechanism
unless, say, the gear is down and the wheels rolling.

On Feb 8, 6:57*am, Amine wrote:
Go around.

Well, let's play the devil's advocate... What if you can't go around?
(E.g. because of engine failure or in a glider). I mean, I understand
why you don't want to deploy spoilers if you're below minimums or if
you're flirting with stall speed. But if you're well above minimums,
with no risk of stalling, I don't see any reason why you shouldn't use
spoilers to bleed the extra momentum/altitude. The only disadvantage
would be that the final approach will be steeper and thereby would not
have the elegance of the perfect glide slope. But that's seems to be
more a matter of taste (and possibly performance) than an actual
safety issue.

This paragragh has several misconceptions as it relates to the OP.
First, An engine out missed in a DC8 or even a two engine jet is
doable and it is practiced all the time in the sim. Spoiler usage in
sailplanes is a completely different kettle of fish and it is normal
to use them into the touchdown in most ships. The crash discused in
the OP happened many years ago and it has been standard in the
industry as long as I can remember (I go back 20 years) to be on
glidpath, on speed, and fully configured with the landing checklist
complete by 1000 AGL (An exception to this is that in VMC you dont
have to be on speed but you must be slowing). No Ifs or Buts. The use
of spoilers below certain RAs and past certain flap settings is
prohibited in the Boeing products and you would be hard pressed to
find both a captain and fo who would ignore operating limitations. So
its not just a mater of taste.

. If there truly was a physical reason why
spoilers should not come out in the air, it would have been an
engineering requirement to systematically disable their mechanism
unless, say, the gear is down and the wheels rolling.

Actually, this is the way it works. Only some of the spoilers deploy
inflight (Either through the spoiler handle or the Aileron/Spoiler
mixer ). The rest of the spoilers will not deploy until the plane is
on the ground.
F Baum

On Fri, 8 Feb 2008 07:40:33 -0800 (PST), "F. Baum"
wrote:


. If there truly was a physical reason why
spoilers should not come out in the air, it would have been an
engineering requirement to systematically disable their mechanism
unless, say, the gear is down and the wheels rolling.

Actually, this is the way it works. Only some of the spoilers deploy
inflight (Either through the spoiler handle or the Aileron/Spoiler
mixer ). The rest of the spoilers will not deploy until the plane is
on the ground.

Or an airspeed lockout. If memory serves they won't deploy, even for
roll assistance, above a certain speed either. Don't they also
deflect at different angles depending on what system is activating
them? Highest angle off the wing is for full in-flight spoiler handle
(and some don't even come up for that), inboard segments deflect at a
greater angle than outboards for roll assistance (which is about 1/2
the angle off the wing compared to full spoiler), and everything comes
up at full for weight-on-wheels spoiler system?

Amine wrote:
On Feb 7, 3:35 pm, Dudley Henriques wrote:
Go around.


Well, let's play the devil's advocate... What if you can't go around?
(E.g. because of engine failure or in a glider). I mean, I understand
why you don't want to deploy spoilers if you're below minimums or if
you're flirting with stall speed. But if you're well above minimums,
with no risk of stalling, I don't see any reason why you shouldn't use
spoilers to bleed the extra momentum/altitude. The only disadvantage
would be that the final approach will be steeper and thereby would not
have the elegance of the perfect glide slope. But that's seems to be
more a matter of taste (and possibly performance) than an actual
safety issue.

After all, the "no-spoiler-in-midair"dogma isn't built in the design
of the pilot interface. If there truly was a physical reason why
spoilers should not come out in the air, it would have been an
engineering requirement to systematically disable their mechanism
unless, say, the gear is down and the wheels rolling.
The "go around" comment was meant as a general rule for any approach
situation that has the aircraft too high and fast for the runway.
Naturally, any approach situation ending with an accident assumes
something went wrong somewhere.
In the case of spoiler use, I can't speak directly to the DC8 scenario
as I'm not DC8 type rated, but obviously in this case, a spoiler
deployment scenario that had the POTENTIAL for problems had been noted
prior by the Captain (at least this is my understanding anyway).
In such a situation, with the first officer making the approach, the
scenario for an in-flight deployment error on the spoilers having been
noted, it would seem obvious to me that a go around call rather than ANY
attempt to use spoilers to save the approach would have been the prudent
call by the first officer.
I'm sure there is more to the story. There always is.
:-)

--
Dudley Henriques

On Feb 8, 9:25*am, Peter Clark
wrote:
On Fri, 8 Feb 2008 07:40:33 -0800 (PST), "F. Baum"
wrote:



. If there truly was a physical reason why
spoilers should not come out in the air, it would have been an
engineering requirement to systematically disable their mechanism
unless, say, the gear is down and the wheels rolling.

Actually, this is the way it works. Only some of the spoilers deploy
inflight (Either through the spoiler handle or the Aileron/Spoiler
mixer ). The rest of the spoilers will not deploy until the plane is
on the ground.

Or an airspeed lockout. *If memory serves they won't deploy, even for
roll assistance, above a certain speed either.

Not too sure on this. On all the jets I have experience with, the
boards are usable to VMO/MMO. On some some of the older ones, like the
727 they will blow down a bit as you approach the pole.


*Don't they also
deflect at different angles depending on what system is activating
them? *Highest angle off the wing is for full in-flight spoiler handle
(and some don't even come up for that), inboard segments deflect at a
greater angle than outboards for roll assistance (which is about 1/2
the angle off the wing compared to full spoiler), and everything comes
up at full for weight-on-wheels spoiler system?

They deploy proportionate to the roll or spoiler input. On several of
the newer airliners there is a flight detent and full range for ground
deployment. Exceeding the flight detent results in buffeting. As an
interesting side note, on the Boeings, if you have the boards about
half way extended and then try a turn, you get a dramatic increase in
the roll rate.

On Fri, 8 Feb 2008 18:14:48 -0800 (PST), "F. Baum"
wrote:

Not too sure on this. On all the jets I have experience with, the
boards are usable to VMO/MMO. On some some of the older ones, like the
727 they will blow down a bit as you approach the pole.

Yea, brain cramp there, you can pull spoiler all the way up but above
some speed they don't go into roll-assist mode.

They deploy proportionate to the roll or spoiler input. On several of
the newer airliners there is a flight detent and full range for ground
deployment. Exceeding the flight detent results in buffeting. As an
interesting side note, on the Boeings, if you have the boards about
half way extended and then try a turn, you get a dramatic increase in
the roll rate.

That must get your attention pretty quick.