Joined: 11 Dec 2005
|Posted: Thu Feb 07, 2008 2:41 am Post subject: 737-300 Takeoff Roll
|Autothrottle and flight director use is recommended for all takeoffs. However do not follow flight director commands until after takeoff. If a possibility exists of a windshear being encountered on takeoff, flight directors should be turned off for airplanes not equipped with a windshear warning system.
A rolling takeoff procedure is recommended for setting takeoff thrust. Besides expediting takeoff it reduces the risk of foreign object damage or engine surge/stall due to a tailwind or a crosswind. Flight test and analysis prove that the change in takeoff roll distance due to the rolling takeoff procedure is negligible when compared to a standing takeoff.
During takeoff, if an engine exceedance occurs after thrust is set and the decision is made to continue the takeoff, do not retard the thrust lever in an attempt to control the exceedance. Retarding the thrust levers after thrust is set invalidates takeoff performance. When PF judges that altitude (min 400 feet AGL) and airspeed are acceptable, the thrust lever should be retarded until the exceedance is within limits and the appropriate non-normal checklist accomplished.
Pilots must use caution when using the nose wheel steering wheel above 20 knots to avoid over-controlling the nose wheels resulting in possible loss of directional control. Use of nose wheel steering is not recommended above 30 knots.
The PM should verify that takeoff thrust has been set and the throttle hold mode (THR HLD) is engaged. A momentary autothrottle overshoot of 4% N1 may occur but thrust should stabilize at +- 2 % N1, after THR HLD. Thrust should be adjusted by PM, if required, to – 0 % + 1 % target N1. Once THR HLD annunciates the autothrottle cannot change thrust lever position, but thrust levers can be positioned manually. The THR HLD mode remains engaged until another thrust mode is selected. Takeoff into headwind of 20 knots or greater may result in THR HLD before the autothrottle can make final thrust adjustment.
THR HLD mode protects against thrust lever movement if a system fault occurs. If THR HLD does not appear, no crew action is required unless a subsequent system fault causes unwanted thrust lever movement. Autothrottle should then be disconnected.
If full thrust is desired when THR HLD is displayed, the throttle levers must be manually advanced, When making a V1 (MCG) limited takeoff, do not exceed the fixed derate thrust limit except in an emergency. In air, pushing TOGA switch advances the thrust to maximum available thrust and TOGA is annunciated.