Rejected takeoff after the takeoff decision speed 'V ', Boeing B737 ...

deciding to reject the takeoff is also not well trained. The study points out that the lack of reference
as to what might make the aircraft unsafe to fly makes it difficult for crews in recognising such a
situation to make an appropriate decision. It should be noted that care must be taken in comparing
the positive (yes) and negative (no) decision to reject the takeoff. The undetermined reasons of
correctness of the decision has increased in the period 1994-2008 versus 1980-1993.
1980 - 1993
1994 - 2008
yes
33,3%
yes
31,9%
no
50,8%
no
44,4%
unknown
15,9%
unknown
23,6%
Figure 12: Correct decision to reject a takeoff. Source: NLR-TP-2010-177 NLR Air Transport Safety
Institute 2010.
5.5 REJECTED TAKEOFF DILEMMA
In the past industry initiatives and studies have identified that rejected takeoffs are a high risk
area. Analysis of available data highlighted that after V 1
and V R
a runway overrun is likely and
could potentially result in aircraft damage and/or loss of life. Statistics further show that the rate
of rejected takeoff is declining. However the rate of high speed rejected takeoffs is not. In general
past studies conclude that if procedures were followed the outcome would have been different.
This conclusion it subsequently followed by the recommendation that flight crew should follow
procedures and act accordingly.
Despite simulator training on rejected takeoffs and instruction on the risks of (high speed) rejected
takeoffs flight crews, when faced with a problem in reality, do not always react desirably and follow
procedures. This is mainly due to the fact that during takeoff the interaction between the aircraft,
environment and crew are tightly related. This interaction may result in a complex situation which
is unfamiliar and difficult to assess.
Technical monitoring and warning system were introduced into aircraft in the past which, when
appropriate, would warn flight crew of a problem. This warning system monitors aircraft condition
and should help flight crew in assessing situations correctly. In this event no warnings were triggered
and the aircraft did not indicate there was a problem. From a manufacture standpoint the aircraft
was therefore airworthy and safe to fly. The control check performed before flight is, in part, to
assess the aircraft state and verify control responses. The environmental conditions like snow and
rain on a runway are addressed in manuals to help flight crew in determining aircraft performance
and make adjustments. This information is used to set preconditions and determine decision speeds.
The fact remains that despite aircraft monitoring and managing preconditions impacting aircraft
performance unexpected situation may occur. On takeoff the flight crew rely on perception and
interpretation of situations. This perception and interpretation provides opportunity for errors
in decision making. Guidance, procedures and training should help pilots in the decision making
process in the critical phase of flight. With the current state of technology and human factors
theories available, a re-evaluation of the rejected takeoff concept and procedures may be useful
and warranted.
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