Originally Posted by
Junkflyer
From the B 717 FCOM: For a normal landing at 80 KIAS smoothly move reverse levels to be in reverse idle detent by 60 KIAS.
At 60 KIAS move reverser levers to forward idle thrust position and stow by 40 KIAS.
I no longer have access to the various FCOMs, but I believe that is common to all Boeing models.
The important thing is to get the reversers out as soon as practical after touchdown - even at reverse idle the ram drag at landing speeds is huge.
Because of that velocity squared thing, the ram drag (and hence the reverser effectiveness) drops rapidly as you slow - plus if you have any reverse thrust asymmetry, directional control can become difficult as you slow and you lose rudder effectiveness.