Page:CAB Accident Report, Eastern Air Lines Flight 304.pdf/13

 from the flight recorder. This was done by utilizing a DC-8 flight simulator programmed to duplicate the weight and c. g. N8607 and the takeoff conditions of Moisant Airport at the time of takeoff. The simulated accelerations and climb data were corroborated by observations of actual DC-8 takeoffs. Integration of the data produced the plot shown in Attachment B. Unknown variations in the winds aloft and in pilot techniques are among several factors which prevent accurate depiction of the flight. It must, therefore, be recognized that the plot in Attachment B cannot be exact, but it does give an envelope within which this flight operated.

It should be noted that the maximum altitude which would have been attained at a point which still allows time for descent to the water is about 7,000 feet for a normal climb at 310 knots. It could have been lower depending on possible power and speed reductions because of turbulence and on the time of onset of difficulties, their nature, and the crew reaction thereto. Within certain limitations there is also latitude for variation in airspeed. An acceleration to, and climb at 310 knots, in the integrations for Attachment B, presented the most plausible appearing flight profile, however, the unaccountability of a period of 40 seconds, explained subsequently, allows for possible airspeed reduction. Such reduction could have been drastic, say, to 220 knots, for a short period of time, or to values in the order of 280 knots, for a relatively prolonged period. Assuming impact to be as late as 0205:40, absolutely latest time, and later than the Board believes the accident occurred, it can be shown that the average climb speed could not have been less than about 250 knots.

With the facsimile flight profile as a guide, and from the collected data concerning the weather, the flight, the aircraft, and crew, preliminary observations and conclusions can be made in preparation for the more important task of isolating causal areas for the disaster.

Analyses of weather conditions in the accident area indicate that Flight 304 entered a broken to overcast layer of fractostratus clouds at approximately 1,000 feet, and that the tops of the clouds were between 5,000 and 6,000 feet. These clouds were associated with a sharp, inverted trough lying across the accident area, oriented northwest-southeast at approximately 5,000 feet. This trough originated from a closed low at that altitude, lying about 55 miles southeast of the accident scene. A regular low pressure trough was oriented north-south at 10,000 somewhat west of the area. The freezing level at the accident site would have been at 9,000 feet.

In view of the weather situation that prevailed, pronounced vertical and horizontal wind shear existed in the accident area. Therefore, it is believed that moderate and probably severe wind shear turbulence was encountered by Flight 304 while in the clouds below 5,000 feet. An analysis of the flight recorder of the jet which departed New Orleans immediately after Flight 304 substantiates the severity of the turbulence in the area. Accelerations to +0.2 and +1.9-g between 2,000 and 6,000 feet, recorded on this tape, indicate severe turbulence. Since known or forecast turbulence along the climb path is the prime criterion for selection of the climb speed, it is probable that the crew of Flight 304, unconcerned about turbulence below 14,000 feet, chose 310 knots rather than the lower rough airspeeds depicted in their flight manual.