Page:CAB Accident Report, Capital Airlines Flight 983.pdf/5

 Investigation of this accident was extended to the subject of decreased braking effectiveness because of wet runway surfaces. The National Aeronautics and Space Administration furnished the results of data compiled when tests were made using various runway surfaces and with varying degrees of moisture on these surfaces. These tests indicated that it was possible under certain conditions (aquaplane) and for the aircraft brakes to be completely ineffective this occurs. Detailed information on this subject may be had from publications listed under BIBLIOGRAPHY at the end of this report.

Analysis and Conclusions

The Board has determined that this aircraft did aquaplane throughout a portion of the landing roll, The white tire marks found on the runway are the color of tire marks definitely associated with aquaplaning. The Board also believes that the approach speed of the aircraft was faster than the recommended approach speed and that this extra speed was partially caused by the lowering of the landing flaps on the final approach. It is further believed that although the aircraft was landed within the first third of the runway, under the conditions which existed, namely a wet runway and without a headwind component, a landing should have been made closer to the approach end, in the interest of safety. Coupling these conditions with the first officer's failure to hear and comply with the captain's order to raise flaps in order to put weight on the wheels, it is easy to understand why an early deceleration was impossible.

The above facts, however, are not the complete story. At some point in the landing roll the captain realized that something must be done immediately or the speed of the aircraft would take it over the embankment at the end of the runway. At that time he was faced with a real emergency and it does not seem in keeping with the gravity of the situation that he would delegate the handling of the power controls to the flight engineer. Recognizing that the power to delegate discretionary with the captain, the Board nevertheless believes that in this instance this was not optimum procedure and that instead the handling of the throttles by the captain may well have resulted in less disastrous results. It is interesting to note that since the accident the company has placed the prohibition on the landing of all Constellation aircraft on runway 32 unless the runway is dry and there is a headwind component.

Probable Cause

The Board determines that the probable cause of this accident was the pilot's action of landing the aircraft too fast on the wet runway under conditions conducive to aquaplaning, making early deceleration impossible. An additional factor was the poor coordination of the crew throughout the approach and landing.

BY THE CIVIL AERONAUTICS BOARD:

/s/ WHITNEY GILLILANDChairman

/s/ CHAN GURNEYVice Chairman

/s/ G. JOSEPH MINETTIMember

/s/ ALAN S. BOYDMember