Dan Applegate

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F.D. 'Dan' Applegate was Director of Product Engineering for Convair, a McDonnell Douglas subcontractor during the early 1970s. He rose from relative obscurity to become the subject of a classic case in engineering ethics when he penned what became known as the "Applegate Memorandum".

Applegate voiced his concerns to management about potential design faults in the McDonnell Douglas DC-10 aircraft’s cargo doors after a cargo door blew off American Airlines Flight 96, a DC-10, over Windsor, Ontario, Canada on June 12, 1972, causing the aircraft to be nearly lost. In his view, these faults could cause the aircraft’s cargo doors to open mid-flight. Should this occur, there would be an instantaneous loss of pressurization of the cargo area. It followed that the pressurised passenger cabin floor, which lay just above, would buckle under the pressure differential. He believed that if this were to happen, the plane’s essential control lines (which ran through the floor) would be cut and the pilot lose control of the aircraft. A potentially fatal crash would seem imminent.

Management, however, believed that his proposed changes would be too costly to implement and so the necessary changes were never made. Applegate never 'blew the whistle' and in 1974, a DC-10 aircraft (Turkish Airlines Flight 981) crashed on the outskirts of Paris, France, killing all 346 people onboard. It was later ascertained that the crash was due to the same technical fault Applegate had foreseen two years prior to that tragic day.

The "Applegate memorandum" included the following:

"The fundamental safety of the cargo door latching system has been progressively degraded since the program began in 1968... The airplane demonstrated an inherent susceptibility to catastrophic failure when exposed to explosive decompression of the cargo component in 1970 ground tests".

The change from hydraulic to electrical (cargo door) actuation was he believed "fundamentally less positive"

"Since Murphy's Law being what it is, cargo doors will come open sometime during the twenty-plus years of use ahead for the DC-10... I would expect this to usually result in the loss of the aircraft".