Page:NTSB Aircraft Accident Report, United Airlines Flight 389.pdf/25

 The two altimeters are served by separate static sources and there is no way in which the information on one altimeter can be displayed on the other. Any error that occurs in one system cannot be displayed on the other instrument thus providing a continuing cross-check capability for the crew. A review of the aircraft records revealed no history of altimeter malfunctions or problems.

1.13

A majority of the witnesses reported an explosion and fire on or just above the horizon over Lake Michigan. Those witnesses nearest the accident, on ships in the area, reported the time of the explosion at about 2120. Several pieces of floating wreckage were recovered which exhibited smoke and soot discoloration particularly on the broken edges. While there was a fire and explosion on impact with the water, there is no evidence of a fire in flight.

Both engine fire extinguisher bottles were recovered with the discharge discs intact. Three fire extinguishers installed in the cockpit and cabin were recovered. The charging cartridge in a water type extinguisher was not discharged. A dry chemical extinguisher was still charged and a functional test revealed that it operated properly. A CO$2$ extinguisher was recovered in a damaged condition and could not be discharged.

1.14

This was a non-survivable accident. Pathological and toxicological examinations of the flight crew revealed no evidence of pre-impact incapacitation nor was there any evidence of foul play.