Reverse thrusts
 

Howcome when i landed on BA767 G-BNWH it didnt use reverse thrusts, i didnt use them neither at JFK or MAN.

BA do not generally use any more than reverse idle since brake wear is lower where the brakes operate at higher temperatures on modern carbon-fibre brakes, lowering costs of fuel use and brake replacement. This is not the case for older metal brakes however.

Reverse is however used where any limiting condition exists such as wet or contaminated surfaces of the runway.

Short turnarounds would also influence a decision as hot brakes on repeated short sectors can result in overheating of brakes, therefore greater use of reverse.

You will have had reverse idle in use.

Interesting answer - thanks.

Thanks, completed but interesting.
On landing they only used speed break and flaps, but they did decrease throttle.
Would they have done reverse thrust in the air before landing?

No. Using reverse thrust mid-air is, as I understand it, pretty much guaranteed to crash the plane.

Was the DC9 or other not certified to use revserse thrust in air as means as slowing down?

Not according to the Concorde drivers and C17 drivers. The C17 can decend at 15,000ft per minute using reverse thrust.

G-BBAE

I suspect that you don't actually know what happened. I'm not trying to be confrontational, but tell what makes you think that reverse thrust wasn't used? What do you think indicates the use of reverse thrust - what are you looking for/at?

Whilst the use of FULL reverse thrust will make a noise and cause a little vibration/shaking felt through the airframe, idle reverse will not be noticeable without looking outside.

As was said, idle reverse is the norm at BA, and monitoring programs will pick up when not used and questions potentially asked of the crew.

And if you were sat by a window looking at the engine and no cowling movement was observed, the reverser was probably locked out on that engine for any number of reasons.....
The other would have been in reverse idle so as not to have a large assymetric braking effect.

:cool:

I'm not sure the 767 is directly comparable to either Concorde or the C17. Unlocking the reversers on a 767 (though I stand to be corrected) would bring the plane down very fast, if not uncontrollably, and BA wouldn't use reverse thrust during flight.

So would a plane be able to land just using spoilers and flaps, but decreasing throttle, not using reversers.
Maybe the 767-300 reverse thrust was quite.

It's unlikely that no reverse thrust was used, but it's more than likely that idle reverse thrust was used - the reversers unlocked (ready for the unexpected) but the engines not powered up. it would've been quiet.

Which aircraft tend to have the loudest reversers, flying on an MD83 ive noticed they can be very loud.

GBBAE

Reversers aren't loud in themselves, reversers merely deflect the jet eflux in a different direction. On modern jet engines they usually just reverse the cold air (that has bypassed the combustion process) leaving the hot stream pushing you forward. Older engines such as the P&W JT8D's on 737's etc had clam shell reversers that reversed all of the flow and were much more effective - I think MD8x's use this technique.

As to noise, if an aircraft uses idle reverse thrust the noise will ne minimal, only when the engines are accelerated above idle reverse does the noise increase. Older engine types are noisier than newer types. It is very noticeable when an aircraft uses full reverse at LHR as the vast majority only use idle - just wait until Air India lands to see what I mean!

To say nothing of the fact that on an MD8x the engine (depending on your seat) can be right outside the window.

GBBAE,

Thrust reversers arent very effective on dry runways, the aircraft was certified for landing without using them. Most airports have noise restrictions on the use of more than idle reverse thrust. So dont be surprised if you see aircraft using idle reverse.

As for reverse in the air, Lauda Air lost a B767 in Bangkok following the opening of a thrust reverser after takeoff.

The Trident and CV880/990 were some of a limited number of aircraft capable of using reverse inflight. Maybe also the DC8.


Mutt.

BN2A Both NWH's thrust reversers are sevicable and have been for quite a while.

Rgds Dr I

1. Modern civil jet airliners can not deploy their reversers in the air as they are activated by the undercarriage squat switch, unless the system has failed. On some aircraft types you can pull up the reversers prior to landing so that the squat switch will deploy the reversers immediately after touchdown. This is not encouraged in case of a failure of the safety system preventing deployment in the air (i.e. the squat switch).

2. Civil aircraft are certificated for landing distance without considering the effect of reversers.

3. Reversers are used generally at heavier landing wights, are only really effective at high speed and are reduced to idle below 80kts. Using reversers above idle at slow speed risks ingesting stones, etc. into the engine.

Flap5,

Not all aircraft have reversers tied into squat switches, by any means. The 737 has a Rad alt ht of 10' as the earliest reverser opportunity. This is to ensure that they are IMMEDIATELY available after landing, especially on slippery runways where they may be the only retarding force.

Without this, If you lose a squat switch and land on a slippery runway which prevents your wheels from spinning up you are in trouble!!

Mutt,

Why are reversers less effective on a dry runway???

Surely you mean they may not be used because the brakes are MORE effective? You cannot change the laws of physics, the same backwards force out of the engine will produce the same retardation, wet or dry?

Try applying your argument to forward thrust, are the engines less effective in the wet? Is that why V1 wet is lower than V1 dry??


I fail to see why using reverse idle in the air would have an instantly catastrophic affect on many aircraft. As long as it is SYMMETRIC!!!!

:D

look you.

Looking at a required stopping distance chart showing the various combinations of brakes/spoilers/reversers on a dry runway, its easy to state that the reversers arent very effective, but as you stated its because the brakes are MORE effective.

Mutt.