A question on reversers

"John Gaquin" wrote in message . ..

wrote in message

If you float in above the threshold a fair bit higher than Vref, is it
acceptable technique to chance the reverser to preclude landing too far
down the runway?

It is bad technique to "chance" anything. Jim is right in that if you're out of position for landing a miss should be
your first consideration.

I can't speak for all transports, but I seem to recall on the 727 and 747 there are lockouts that prevent reverse
actuation in flight. Not 100% sure of the physical lockout on the 727, and too lazy right now to look it up. :-) I
do recall that inflight reverser use was possible on at least some models of the DC8.


http://en.wikipedia.org/wiki/Lauda_Air_Flight_004

wrote in message

John, I'm sure the Thailand Air Lauda A320 crash of about 10 years ago
has escaped your attention

The pilots somehow accidentally deployed the reversers on finals and
couldn't recover the craft

The Lauda aircraft was a B767, and the accident occurred as a result of a
system failure some 20 minutes or so after T.O., not during a landing
approach. In normal operation, inflight reverse should be prevented in the
767.

In my post I was speaking in general terms, that as a matter of design,
operation of reversers in flight is usually prevented. However, there are
some exceptions, and in the event of a system failure or malfunction, all
sorts of unanticipated things can occur.

".Blueskies." wrote in message

http://en.wikipedia.org/wiki/Lauda_Air_Flight_004

I'm sorry, but I don't see how that relates to my post. Lauda crashed due
to a malfunction.

John Gaquin wrote:
http://en.wikipedia.org/wiki/Lauda_Air_Flight_004

I'm sorry, but I don't see how that relates to my post. Lauda crashed due to a malfunction.


Oops, thanks. I was thinking all along that a pilot deployed it
accidentally. Or was that the EgyptAir crash off Massachussetts?...

Ramapriya

It seems that was an act of terrorism, the co-pilot for what
ever reason seemed to be crashing the aircraft, but that was
just some news reports, don't know if there ever was a final
and official determination made.



wrote in message
oups.com...
| John Gaquin wrote:
| http://en.wikipedia.org/wiki/Lauda_Air_Flight_004
|
| I'm sorry, but I don't see how that relates to my post.
Lauda crashed due to a malfunction.
|
|
| Oops, thanks. I was thinking all along that a pilot
deployed it
| accidentally. Or was that the EgyptAir crash off
Massachussetts?...
|
| Ramapriya
|

On the B727, the throttles must be in idle position in order to activate the
reversers. In the limitations section of the AFM, one is advised that
operation of reversers is not permitted in flight. I'm not aware of other
interlocks (Z-bar, etc)
"John Gaquin" wrote in message
. ..

wrote in message

If you float in above the threshold a fair bit higher than Vref, is it
acceptable technique to chance the reverser to preclude landing too far
down the runway?

It is bad technique to "chance" anything. Jim is right in that if you're
out of position for landing a miss should be your first consideration.

I can't speak for all transports, but I seem to recall on the 727 and 747
there are lockouts that prevent reverse actuation in flight. Not 100%
sure
of the physical lockout on the 727, and too lazy right now to look it up.
:-) I do recall that inflight reverser use was possible on at least some
models of the DC8.

In any event, I wouldn't consider use of reverse immediately before
landing
a good idea.

Jim Macklin wrote:
But I agree, jets require the
squat switch (unless there is a malfunction) to deploy
reverse.

I read recently the C-5 that crashed at Dover, DE had a #2 engine
reverser unstow right after takeoff. The crew attempted the approach
with full flaps instead of partial flaps per the POH and the sink rate
was too high to overcome.

wrote:
If you float in above the threshold a fair bit higher than Vref, is it
acceptable technique to chance the reverser to preclude landing too far
down the runway?

Thanks in advance,

Ramapriya

Depends on the aircraft. The DC-8 used to allow two of the
engines to be flown in reverse on approach.

wrote in message
If you float in above the threshold a fair bit higher than Vref, is it
acceptable technique to chance the reverser to preclude landing too far
down the runway?

The acceptable technique is to discontinue the approach and go around for
another try. Unstabilized approaches account for a large number of airline
landing incidents.

As for the use of reverse, most airplanes prohibit using thrust reversers in
air because of unacceptably high sink-rates, assymetric thrust when one
deploys and one does not, or flight control surfaces losing effectiveness
due to disrupted airflow.

D.

You can go-around even after touchdown. A missed approach
begun at 100 feet on a CATII ILS may result in the aircraft
touching down, which is why you don't retract the landing
gear until a positive rate of climb is established.


--
James H. Macklin
ATP,CFI,A&P

wrote in message
oups.com...
| Capt.Doug wrote:
| wrote in message
| If you float in above the threshold a fair bit higher
than Vref, is it
| acceptable technique to chance the reverser to
preclude landing too far
| down the runway?
|
| The acceptable technique is to discontinue the approach
and go around for
| another try. Unstabilized approaches account for a large
number of airline
| landing incidents.
|
| As for the use of reverse, most airplanes prohibit using
thrust reversers in
| air because of unacceptably high sink-rates, assymetric
thrust when one
| deploys and one does not, or flight control surfaces
losing effectiveness
| due to disrupted airflow.
|
| D.
|
|
| Thanks, Capn; nice to hear from you again
|
| Cn you decide to go-around as late as when you're already
above the
| runway (unless the "above the threshold" bit of my msg got
buried
| somehow)?
|
| Ever since I first read about it, the asynchronous
possibility of
| reversers has struck me as worrisome, and that's the
reason I
| hesitantly mentioned it on the grass-landing thread.
Hadn't however
| reckoned for the howlers it elicited
|
| Ramapriya
|