Page:CAB Accident Report, Continental Airlines Flight 12.pdf/12

- 12 - 2. ANALYSIS AND CONCLUSIONS

2.1

N70773 had been maintained in an airworthy condition and there was no mal- function of any of the aircraft's structure, systems, or components that con- tributed to the accident.

The crew was certificated, and qualified in accordance with.existing company and Federal Aviation Agency Regulations. The evidence indicates that the instrument approach and landing at Kansas City was conducted in accordance with, company operating procedures except that the aircraft weighed more than the company's imposed 160,000 pounds maximum gross landing weight. This excess weight was below the FAA landing weight restriction of 175,000 pounds for B-707 operations into Kansas City.

The crew of Flight 12 was not provided with adequate weather information, by the approach controller, upon which to base a decision to land at Kansas City under the existing runway conditions. By virtue of the controller's failure to advise them that significant weather existed over the airport, the crew had every right to assume that their only concern was a 700-foot ceiling and two miles visibility. This evaluation appeared to be borne out when they found they could see the runway from a point 1.8 nautical miles out, at which time they were clear of the clouds. They also knew that TWA Flight 84, a large four engine jet transport, had landed, without reported difficulty, about four minutes ahead of them. This situation was compounded by the failure of the company representative to perform an inspection of the runway conditions existing at the airport, and report them to Flight Control to be relayed to Flight 12, and also to inform the dispatcher of the heavy precipitation occurring at the airport.

Touchdown at about 137 knots, occurred approximately 1,050 feet past the runway threshold and was solid, with no bounce. This is evidenced by the scrub marks on the runway and the testimony of an aeronautically qualified passenger aboard the aircraft. Spoilers were extended, wheel braking begun, and reverse thrust was initiated immediately after landing. A lack of decelerating forces was noted by the crew and several passengers. Heavy spray was thrown up by the aircraft as it progressed down the runway. Due to excessive cycling of the wheel anti-skid system the captain increased reverse threat from 80 percent to  100 percent. When it became apparent to him that the aircraft would not stop on the runway, the captain cocked the aircraft to the left by advancing the Nos. 3 and 4 engines into forward thrust and the use of left rudder. The aircraft weather-cocked 35 degrees to the left but continued to slide down the runway going off the concrete at about 40 knots.

The Board is unable to accurately determine how much_water was standing on the runway; however, it is estimated that the water depth exceeded 0.3 inches at the time of landing. This amount of water is more than enough to induce dynamic hydroplaning. It would have exceeded the average tread depth of all but one of the tires, causing them to react as smooth tires above this aircraft is dynamic hydroplaning speed of approximately 102 knots.

The evidence of rubber reversion on all the tires indicates that there were periods of locked wheel skid where the tread was in contact with moist pavement,