737 Reverse before Touch?
 

Hello my friends...is this a normal procedure for the 737-700, with TR deployed before touch?
IMHO i tought it was inhibited by the aircraft....but i was wrong.
Even is it a SOP to retract the spoilers keeping the deseceleration run?


Tanx for your kind explanations in advance...JF.

The B737 NG is capable of deploying the reversers below 10' RA, although it is specifically prohibited under the Limitations section of the FCOM. I believe that was developed due to an Airbus event in which the On-Ground Sensors did not operate correctly, so they were unable to apply brake, spoilers or reverse thrust on a landing many years ago.

Cancelling spoilers may have been used as a method of disconnecting the Autobrake. It's not a recommended method, but it does work.

Aye, this indeed seems to be a result of the LH A320 overshoot in Warsaw in the early 90s - I've unfortunately seen the reversers opened while the airplane was still flying, not a good experience - makes for quite a 'positive' touchdown... :sad:

Don't think it has anything to do with the warsaw incident as it was the same on the classic which entered service in the 80s. Probably just some quirk in the system that survived since the jurassic.

Had my smoothest greaser with accidentally opening the reverser around 3ft, simply didn't notice when we touched down and thought we were on the ground already. But that was in a -300, not an NG.

D'oh, you are right, the classics had the same system logic... :ugh:

I think the classics allow deployment at 20' RA

At 10 RA if commited for said craft sounds like a safe point to deploy at , may result in a firm landing. None the less to arrest a long or floating LNDG, sounds like a good idea. Hell the DC-8 could deploy to my knowledge as speed brakes 1 & 4? On the 73x would you not be on the ground by the time that actual reverse thrust would be spooling up?

I don't think it is wise due to the potential for asymmetric reverse deployment and the fact that you are absolutely committed to land as a safe baulked landing not being reliably possible once the reversers are deployed.

The Tupolev 154 has long been capable of this, there are several clips of it doing so on YouTube taken by bemused spectators

Tupolev 154 Reverses Power Before Touchdown! - YouTube

Some have either been taught to, or have developed the habit of, sliding their hand forward on to the reverse thrust levers once the thrust levers have hit the idle stops, even if they are still in the air. I guess they feel they need to be ready for a super fast deployment of reverse thrust. I have had to tell F/O's not to do it on a number of occasions.

Those that do this & then hold pressure on the reverse thrust levers to get immediate deployment once the interlocks release (as they are supposed to), will find that they will get deployment while still in the air. I have yet to discover if they are not aware that the reversers have deployed before they were on the ground, or if they are deliberately deploying them in the air.

Your hand is supposed to remain on the thrust levers until the aircraft touches down & only then be moved to the reverse thrust levers for reverser deployment.

- exactly my experience and I believe it has come from trainers and Captains who have got a bit excited about the Boeing wording:

"After touchdown, with the thrust levers at idle, rapidly raise the reverse thrust levers up and aft to the interlock position"

and interpret this as the need to 'panic' the reversers into action as the wheels touch. I had one F/O so trained whose fingers crept along the levers during the flare and actually popped the reversers in the air - but had no idea he had done so! I recall a previous Boeing manual which said something like 'without delay....'

Exactly!

It never ceases to amaze me how some get too involved in the fine detail & fail to step back & see the bigger picture or, as in this case, move their focus out & read & comprehend the entire sentence, paragraph or section of the manual.

The "After touchdown" bit seems to be missed as they read the rest - "with the thrust levers at idle, rapidly raise the reverse thrust levers up and aft to the interlock position"

I know of one case where the pilot had developped an habit (I mean non-standard procedure) that relied on the interlocks for preventing reverse thrust (actually beta range in a turboprop).
The day the interlocks failed, the outcome was all POB dead but for 2 survivors.
http://www.mt.public.lu/ministere/se..._EN_fokker.pdf

Luc

IIRC the event in which WOW (air/ground) switches got bashed was an IB A330 at Quito, perhaps three years ago. Multiple security camera snips showed reversers & spoilers failing to deploy, thus an overrun. :{

edit:
Although I had some difficulty with the usual accident documentation sites, I finally found it (an A340, not A330):

Nov 9, 2007 ... An Airbus A340-642 passenger plane, registered EC-JOH, sustained substantial damage in a landing accident at Quito-Mariscal Sucre Airport (UIO), Ecuador.