PPRuNe Forums - View Single Post - The B737 Landing Roll - F/O handling and Captain Hovering..
Old 11th Jul 2007, 13:34
  #18 (permalink)  
Centaurus
 
Join Date: Jun 2000
Location: Australia
Posts: 4,189
Likes: 0
Received 19 Likes on 6 Posts
Yes - please leave the reversers 'as they are' at hand over. 9 times out of 10 they are stowed at handover and I have to redeploy them
Firstly, judging by the variety of opinions expressed in the preceding replies, the original correspondent A37575 has hit the nail on the head in his questioning of captain's habits in terms of when they prefer to take over control during a landing roll. Whether or not this detail should be published in company SOP is a matter of opinion. There is surely a limit on how much needs to be published in the Great Book as against what is generally accepted by competent well trained crews as commonsense airmanship.

Secondly, in reply to the boxed quote above, some may consider it's is a bit damned late to be redeploying the reversers after they have already been stowed or close to be stowed. It is well known that below 80 knots the effect of reverse is greatly diminished as a retardation device unless on a very slippery surface.
Couple that with reverse idle the time to attain full reverse takes at least 7 seconds, when at the same time wheel braking on a dry runway is very efficient. Therefore the use of reverse idle as a "standby" in case more decelleration is suddenly required for whatever reason - is just fooling yourself.
Operational margins published in the FCTM indicate a rejected take off using manual brakes and full reverse on a dry surface the amount of length saved is around 180 feet compared with no reverse. With RTO the saved distance is probably even less. That distance reflects the efficiency of the braking system and spoilers because by the time reverse thrust levels are high enough to significantly reduce the landing run, the brakes have done their job and cut speeds back down to where reverse is least effective. Using idle reverse as a perceived precaution in case sudden high reverse is needed late in the landing run, is simply a contradiction of facts. Reverse is most effective if applied at high speed and quite ineffective at low speed.
Centaurus is offline