Not having flown anything but the 737 variants I cannot comment on the 777.
The 737 FCTM makes it crystal clear that assuming RTO is serviceable, the first action after closing the thrust levers is to manually apply the speed brake lever to up. As some one mentioned earlier, the importance of prompt speed brake operation cannot be overestimated - especially on a contaminated runway.
The speed brake is on the captain's side of the throttle quadrant and it is therefore logical that he operates the speed brake as he will be the handling pilot in an abort. It is cack-handed to have the copilot responsible for operating the speed brake because he has to reach far over the captains hands to get a grip on the speed brake lever. Every second delay in applying speed brake extends the abort distance.
The auto-speed brake operation in the 737 is actuated by the first selection of the reverse thrust levers. That means providing the captain selects the reverse levers asap, there is little difference in time between auto-speed brake actuation and manual speed brake actuation.
That said, auto-actuation of the speed brakes have been known to fail without prior warning. Which is precisely the reason why this failure mode is available on the simulator instructor panel.
Boeing foresaw this possibility and that is why they advise the speed brake should always be selected manually in an abort rather than blindly rely on the automatic function. The beauty of this is another Boeing feature and that is if the captain forgets to select the speed brake manually the auto-extension serves as the fall-back position providing of course reverse thrust is selected. Fail safe as it were.
If the crew rely solely on the auto-speed brake function and it fails to actuate on reverse thrust lever selection, experience has shown it takes a couple of seconds to realise the speed brake lever has failed to come up automatically. By the time someone gets his hand on the speed brake lever to pull it manually, vital lift dumping is delayed and the abort (or landing) distance is extended.
Last edited by Centaurus; 10th Aug 2011 at 08:46.