of 5 miles the pilots being tested decided that a collision course existed in 16 percent of the cases. In these instances a horizon line was available which would assist the pilot in determining the relative altitude of the intruder aircraft. In those instances where a horizontal miss vector of 250 feet existed at five miles initial range and a reference line was not available, a decision was made that a collision course existed in 52 percent of the cases. It is not unlikely, therefore, that when PAA 212 was observed through the first officer's. side window, against a featureless background at a five-mile range, the PAA aircraft could well appear to be at the same altitude as EAL 663 and thus present a collision threat.
The remaining questions concern the delay in the execution of the turn to 170 degrees, which instruction was initiated at 1825:21, received by the crew at 1825:26 and acknowledged at 1825:31, and the reason for a faster than normal turn.
On the basis of the data used in developing the probable flightpath on Attachment #4 the turn would have been established at 1825:43 or about 17 seconds after the receipt of the turn instruction by the crew, Approximately five seconds of this would be pilot/aircraft response time. It is our belief that in the remaining 12 seconds the crew of EAL 663 was attempting to locate their traffic and assess the collision potential. Since this traffic was at their 3 o'clock position, instead of 2 o'clock, it probably would not be seen by the captain, but could have been and likely was seen by the first officer. A continued preoccupation with potentially conflicting traffic, both prior to initiating the turn and afterwards, is implied in EAL 663's failure to contact either the company or the New York Center after concluding communications with the Kennedy Departure Controller at 1825:36, some 50 seconds before the aircraft passed each other. The 12 seconds delay is reasonable and consistent with the DR-1 controller's testimony on this subject.
EAL 663 commenced the turn from 090 degrees to 170 degrees at approximately 1825:43. With the EAL's aircraft in a 35-degree banked nearly level turn and with PAA 212 approximately 700 feet lower and four miles away at 3 o'clock instead of 2 o'clock, PAA 212 would not be visible to the captain of EAL 663 until he was nearly around the turn and on the rollout. Since PAA 212 would not be visible to the captain throughout his turn, it would then be necessary for him to locate this traffic upon completion of the turn. At this time EAL 663 would be on a nearly head-on, converging course with PAA 212. Separation would be on the order of 2-1/2 miles. The time of completion of the turn would be about 1826:03. PAA 212 would be at approximately 3,050 feet altitude, according to the flight recorder data. On the basis of the times ascribed to the events shown on the PAA 212 flight recorder readout, PAA 212 started a left turn to the assigned heading of 360 degrees at 1826:00. The results of this turn would be to produce even more of an apparent collision track than before. After the turn to 170 degrees the captain of EAL 663 would have had a total of 23 seconds available to him in which to (I) locate the other aircraft, (2) assess the degree of threat, (3) initiate an avoidance maneuver, and (4) complete the avoidance maneuver. During this time little or no attention could be given to the instruments because of the necessity to keep the other aircraft under continuous observation.
In view of the close proximity of PAA 212 and the decision times shown in the Sperry Gyroscope Company experiments it is apparent that the captain's decision would have to be made almost simultaneously with his observation of the traffic.
