We have discussed this passage with several flight instructors. All of the turns described are standard and consistent with KennedyŪs flight plan, except for the last one. (the time is given in military fashion. 2140:15 means 9:40 p.m. and 15 seconds) The last paragraph is the one that should attract your attention. In the course of 10 seconds (between 2140:15 and 2140:25) the plane goes from being level to having a bank angle in excess of 45%. This means that the plane is halfway to being completely sideways, one wing pointed at the sea, the other at the sky.
It is a sudden, suicidal, plunge straight down. It is not a gradual
turn, as described by the NTSB (pages 17 and 18)
descriptions of various disorientation scenarios.
žAircraft Performance Study
"An aircraft performance study was performed by a Safety Board specialist
using the Board's computer simulation program.
According to the specialist's report, airplane performance data for the final portion of the flight were calculated using radar,
aircraft, and weather data. Performance parameters were then computed for the final 7 minutes of the flight.
"The calculated parameters showed the airplane initially descending
from 5500 feet at descent rates varying between 400 and
800 fpm, at 2133:40. At 2137:20, the airplane attained a steady descent rate of close to 600 fpm as the airplane passed
through 3,000 feet. During the entire descent from 5,500 feet, the calculated airspeed remained near 160 KIAS, and the
flightpath angle remained close to -2 degrees. About 2138, the airplane started to bank in a right-wing-down (RWD) direction toward a southerly direction. Calculated parameters indicated an almost constant roll angle of 13 degrees RWD and a vertical acceleration of 1.09 Gs while executing the turn. About 30 seconds after the turn was initiated, at an altitude of 2,200 feet, the airplane stopped descending. The airplane then climbed for the next 30 seconds, attaining a maximum climb rate of 600 fpm. During the ascent, the airplane finished the turn to a southeasterly direction, reduced speed slightly to 153 KIAS, and returned to a wings-level attitude by 2138:50. By 2139, the airplane leveled at 2,500 feet and then flew in a southeasterly direction with wings level while increasing airspeed back to 160 KIAS.
"At 2139:50, the airplane entered a left turn, while slightly increasing
altitude to 2,600 feet. The airplane reached a maximum
bank angle of 28 degrees left-wing-down (LWD) and a maximum vertical acceleration of 1.2 Gs in this turn. When the
maximum LWD bank angle was obtained, the altitude started to decrease at a descent rate close to 900 fpm. The LWD
attitude was maintained for approximately 15 seconds until the airplane was heading towards the east.
"At 2140:07, the airplane bank angle returned to wings level. At 2140:15, with the airplane continuing towards the east, it reestablished a descent close to 900 fpm and then started to increase its bank angle in a RWD direction at nearly a constant rate. As the airplane bank angle increased, the rate of descent increased, and the airspeed started to increase. By 2140:25, the bank angle exceeded 45 degrees, the vertical acceleration was 1.2 Gs, the airspeed increased through 180 knots, and the flightpath angle was close to 5 degrees airplane nose down. After 2140:25, the airplane's airspeed, vertical acceleration, bank, and dive angle continued to increase, and the right turn tightened until water impact, about 2141."