737 thrust reversers deployed before touchdown..?

[beachfront71]

Guys.

just curious if this is possible or standard practice...

was at SNA the other day and could have sworn I saw a Southwest plane deploy thrust reversers while still 6-8 feet in the air..

thanks for any comments..

[Final 3 Greens]

I didn't think that this was possible on a 737. IIRC, 'squat switches' in the landing gear prevent it (from what 737 pilots have posted here in the past.)

On the other hand, the DC8 and Trident could do it.

[profot]

19R is short for a 73 but not short enough to attempt that caper even if it were possible which it isnt

[Mr @ Spotty M]

Yes it is possible as l recall, my understanding is with a rad alt of 10 ft or less they can deploy. However l believe it is not possible on UK reg a/c, not sure if it is European wide also.

[profot]

It is theoretically possible, at least on the 200 series to deploy them at low RA as it takes a few seconds for operation and in theory you will be on the deck at time of deployment

I would be surprised to learn of any airlines using this as sop, sna is shortish but not short enough for that

[kenparry]

It is theoretically possible, at least on the 200 series to deploy them at low RA as it takes a few seconds for operation and in theory you will be on the deck at time of deployment

I disagree. The -200s I flew had a nosegear squat switch in series with the standard Boeing main gear switch and both had to be made to enable reverser deployment. There was no rad alt input in reverser deployment on any -200 I flew, so airborne reverse was not possible.

[Mr @ Spotty M]

That you will find was a CAA requirement, others only operated using the main gear squat switch. This is how a tragic accident happened in Canada many years ago, where the T/Rev deployed on a go around.

[profot]

I seem to recall they changed the reversers on the early 200's because of this from the rohr versions

Incidental really as they are not flying this series into sna and i doubt very much if any pre hull no.135 200s are still flying anyway

[Flying Torquewrench]

Even on the 737NG you can theoretically still deploy the T/R while airborne.

Straight from the Boeing 737NG AMM part 1.

"The Thrust reverser can be deployed when either radio altimeter senses less than 10 feet altitude, or when the air/ground safety sensor is in the ground mode."

[Capt Chambo]

On the B737-300~900 it is possible to deploy the thrust reversers when either Rad Alt senses less than 10' altitude or when the air/ground safety sensor is in the ground mode provided the thrust levers are at idle.

It is however prohibited to intentionally deploy the thrust reversers in flight.