Originally Posted by
flash8
As I recall possible below 20' RA on the classic (possibly 10') but in my opinion not very wise! I'd go as far as to say no practical reason whatsoever beyond get down-itus.
I have a vague memory that the 737 uses Radio Altimeter to enable the T/R (I thought it was 5 ft., not 10, but as I noted it's a vague memory). This is different from other Boeing installations, which use Weight On Wheels (WOW) -often in combination with the Radio Altimeter - to enable the reversers. Apparently the low wing on the 737 can allow it to float in ground effect enough to prevent WOW from going true.
Dave T - really, really surprised if the 787 enables the reversers only with RA - I'd expect as a minimum that the track lock would have WOW logic. There is a reason why we don't do that on the other aircraft - RA can be fooled in heavy weather...
Then again, the 787 did a lot of 'reinventing the wheel', throwing out decades of experience on why we did some things the way we did.
