Jay Beckman wrote:

The safety board has been looking at when the pilots activated the
engine thrust reversers, which help slow a plane once it's down. They
were turned on 18 seconds after touchdown; Four or five seconds is
common."


I believe this last sentence does not accurately explain what may have
happened.

The thrust reversers did not *deploy* until sometime after touchdown
(possibly due to lack of wheel spin up.) This does not mean they weren't
"selected/activated" ASAP on landing.

Jay B


If I'm not wrong, it's a requirement that reversers aren't deployed
until the plane is firmly on the ground (to probably preclude unwanted
torquey stresses on the landing gear due to asynchronous spooling,
should it occur), and that may have had a bearing on when the pilots
chose to activate them. I also recollect reading somewhere that you're
barred from using reversers if there's a tailwind of 10 kts or more, or
when the touchdown speed is too high (can't think of a reason why that
should be so).

The reversers not deploying despite being activated much earlier might
not be very probable. I say that because 737 isn't yet fly-by-wire
where the automation systems augment/refine and even override pilot
input (remember the Jo'burg runway overrun of an A340 in early '04?).

Ramapriya