Considering an engine inoperative case, where the engine failure occurs earlier than 1 sec. before V1, then additional distance is required to accelerate to VR on one engine and as a consequence the lift off point will move further down the runway. The screen height achieved at the end of the runway will be lesser that 35 feet (depending upon how much time before V1 the engine has failed / thrust loss has taken place). An engine failure 8 Kts prior to V1, results in a screen height of 15 to 30 feet for a field length limited weight take off.
The crew must weigh the situation spontaneously in a dynamic environment, which is indeed a complex task and therein lies the key to safety in flight. The final lesson learned from the past 30 years of reject(ed) take off history suggest that 80% rejected take-offs were potentially avoidable through appropriate operational procedures such as better : intra cockpit communication, pre flight briefing, pre flight checks, workload distribution procedures, pilot techniques. Also 55% of these, involved events where, the aircraft were capable of continuing the take off and landing back, thus using full length of the runway for stopping.
The decision to reject and the execution of a reject is vested with the Captain, irrespective of the crew member performing the take off. As such when the Captain is not performing the take off himself, he should be ready to take over control immediately when required. The Captain must keep his hand on throttles (rear extensions ) till V1. Maintaining a safe flight path is of primary concern. After V1 and in flight, if the Captain is not the pilot flying, then the Captain should take over the controls at an appropriate time and opportunity, keeping in mind the flight path and safety of the aircraft.
Any crew member noticing a malfunction / abnormality must announce it clearly and precisely. Depending upon the abnormality and the airspeed at the moment, the Captain decides either to continue the take off or to reject the take off by announcing his intention as "GO" OR "STOP" as the case may be. If the take off was being performed by a crew member other than the Captain :-
After announcing "GO" the Captain (if not the PF), takes over control 'at the/an appropriate moment ' by announcing "I have Control" thus taking over control of the a/c and the other CM reverts to the duties of the PNF & simultaneously stating "You have Control ".
Note: To clarify, ' at the appropriate moment' means that during rotation or any such crucial moments, the Captain may use his discretion to delay taking over ( unless the flight path is being compromised) so that a smooth transition is achieved. 中國航空網 www.k6050.com 航空翻譯 www.aviation.cn 本文鏈接地址：Airbus ABNORMAL/EMERGENCY PROCEDURES 空客非正常/緊急程序(5)
