Originally Posted by
milky
Boeing changed the order of reversers and spoilers because guys were reacting too quickly and actually trying to engage the reversers too quickly which causes damage. The order changed to go to reverse, manually ensure the spoilers are up, then pull the reversers up about a year or so ago for use on the 73 700.
I don't know that this is true on modern engines. Its just to guarantee performance data for all scenarios including MEL deferrals. Rejects are based on forward Idle and ground spoilers for almost all aircraft (however 747-400 was certified for RTO with eng out + (x) operating reversers incorporated into the data*, and maybe some other aircraft as well). So you have to get idle, ground spoilers, and brakes, and then you just get bonus stopping capability with TRs, hence why they come last. I occasionally flew with the autospoiler and or TRs MEL'd, meaning if I tried to do an RTO with reversers first, I may have not gotten the spoilers to come up in time to guarantee performance data.