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.