What happened
During an overwater flight lasting approximately 4.3 hours, the crew notified air traffic control that they had only 15 minutes of fuel remaining. Shortly thereafter, three of the four engines on the aircraft type lost power. While attempting an emergency landing, the aircraft struck a levee, causing significant damage to the airframe. The majority of the wreckage settled in a nearby drainage canal. On July 22, 1988, the bodies of the crew were recovered from the water.
Records indicated that the flight had departed El Salvador with seven hours of fuel onboard. However, an unexplained discrepancy of 2.7 hours of missing fuel was noted. Although no fuel spills were observed by ground personnel during pre-flight operations, a later inspection of the wreckage revealed an open drain valve located within the number four engine nacelle. A metallurgical analysis suggested this valve had remained in the open position for a prolonged period. During the impact, the number one, number two, and number three engines were not producing power.
Findings
Investigation into the fuel loss concluded that the primary factor was fuel exhaustion. While ethanol was detected in the blood of the pilot and co-pilot, investigators determined this was a result of postmortem chemical changes rather than impairment. The aircraft's crossfeed valves were found in their crossfeed positions at the time of the accident. The descent and subsequent impact occurred during dusk conditions, with the aircraft striking a dirt embankment and landing in water.