Originally Posted by
tdracer
Some pilots have a very bad habit of lifting the reverse levers prior to touchdown - depending on the air/ground logic to prevent deployment until they actual land. The good news is that, since Lauda, the air/ground protection is good enough that the probability of the reversers actually deploying prior to touchdown is very remote - the bad news is that if there is some sort of latent fault that allows a reverser to deploy, they'll probably crash
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We did a big investigation of this on the 757 years back, where lifting the reverse levers was causing a rash of nuisance fault messages. We instrumented a couple in-service 757s and sure enough, about 1% of the landings they were lifting the reverse levers prior to touchdown - sometimes by as much as 10 seconds
All that being said, I'd be hard pressed to come up a scenario for how doing that could cause a nuisance TCMA trip...
On the NG you can select reverse thrust from 10 ft above the runway. Limitations forbids this, but it is possible. Going back 20 years, some of our guys did this on short runways. It works if you know what you are doing, but it’s very easy to end up with a firm landing.
You you manage to select reverse 10 seconds before touchdown, you will hit very hard. 😳