NTSB Aircraft Accident Report
2
crew described the engine spool-up (as thrust advanced to the predetermined reduced power setting
for takeoff) as “normal.” At 1431:32, the first officer made a routine callout indicating that the
airplane’s airspeed was 80 knots.
FDR data showed that, at 1431:43.4 and with the airplane’s airspeed indicating 128 knots,
the longitudinal acceleration decreased suddenly from 0.23 to 0.13 G, and variations in the vertical
acceleration increased in magnitude, consistent with a sudden engine imbalance causing a
vibration force on the airframe.
5
About the same time, the CVR recorded a “bang” sound and the
captain’s statement “whoa.” Both flight crewmembers reported hearing the sound and feeling the
airplane drift to the right. At that time, the airplane was about 3,300 ft from the N5 intersection.
The captain initiated the rejected takeoff maneuver; FDR data showed that the throttles were
moved to idle power at 1431:45.
6
One second later, the autobrakes, which for takeoff had been
selected in the “RTO” (rejected takeoff) position, activated.
7
At that time, the airplane’s airspeed
was 134 knots, which was also the calculated takeoff decision speed (V
1
). The auto speedbrakes
activated about 2 seconds after the autobrakes.
8
In a postaccident statement, the captain indicated
that he rejected the takeoff because he thought that the airplane was “unable/unsafe to fly.”
9
At 1431:50, the first officer contacted the air traffic control (ATC) tower and stated that
the airplane would be “stopping on the runway,” and the tower controller responded, “roger roger
fire,” which was the flight crew’s first indication that a fire had begun. The first officer asked the
controller if he saw any smoke or fire, and the controller stated, “yeah, fire off the right wing.”
10
At 1432:00, the CVR recorded the first officer stating, “okay, send out the [fire] trucks,” and a
About 56 hours of operational data were retained on the recording medium, including about 11 minutes of data from
the accident flight, from 1422:15 to 1433:09.
5
(a) G is a unit of measurement of acceleration and deceleration. One G is equivalent to the acceleration caused
by the earth’s gravity (about 32.2 ft/sec
2
). (b) FDR data indicated that, between 1431:21 and 1431:37, the airplane
reached a steady longitudinal acceleration of about 0.25 G. Between 1431:37 and 1431:43, the longitudinal
acceleration began to slowly decrease. When the longitudinal acceleration decreased suddenly at 1431:43, the vertical
acceleration also decreased, from 1.14 to 0.97 G. The vertical acceleration before that time had basically been steady—
between 0.98 and 1.02 G.
6
The CVR recorded a sound similar to throttles contacting idle stops and a sound similar to a decrease in engine
rpm.
7
Autobrakes are selected in the RTO position during takeoff to provide maximum braking in the event of a
rejected takeoff. During a postaccident interview, the captain described the performance of the RTO autobrake system
as an “aggressive stop.”
8
During that time, the FDR recorded the flight’s maximum airspeed—135 knots—which decreased by 15 knots
by 1431:49.
9
American Airlines 767 Operations Manual, QRH (Quick Reference Handbook) indicated that a rejected takeoff
was a “non-normal maneuver.” According to the QRH, “the captain has the sole responsibility for the decision to reject
the takeoff. The decision must be made in time to start the rejected takeoff maneuver by V
1
. If the decision is to reject
the takeoff, the captain must clearly announce ‘REJECT,’ immediately start the rejected takeoff maneuver, and assume
control of the airplane.” The QRH also stated that a takeoff should be rejected between 80 knots and V
1
if an engine
failure, fire, or fire warning occurred or if the airplane was unsafe or unable to fly and that “the crew member observing
the non-normal situation will immediately call it out as clearly as possible.”
10
National Transportation Safety Board (NTSB) investigators sat in the first officer’s seat in an exemplar
American Airlines 767 airplane to determine whether the right wing and right engine could be viewed from that
position. The investigators found that the right wingtip was visible only when the occupant’s head was pressed against
the closed right-side cockpit window. The right engine was not visible with the right-side cockpit window closed. The
right engine was visible with the window opened to allow the occupant to look outside the fuselage.