HUD has as deacceleration scale on it.
Spoilers w/full reverser is approx. the same as autobrakes 2.75 at touchdown.
So initially with a/b's 2 they're not doing anything until the a/c slows and the deacceleration from the T/R's and spoilers decreases to '2' or less.
Last edited by misd-agin; 10th October 2011 at 00:04.
Reason: added "at touchdown"