On the second anniversary of the disappearance of Malaysia Air flight MH370, this blog explored the known facts and concluded, “Unless and until the wreckage is located on the ocean floor and the flight data recorder and cockpit voice recorder data recovered, the most plausible scenario is deliberate human action, most likely by one of the cockpit crew.”

Thereafter, the search area was refined, but in January, 2017 further search efforts were ended. As a result, recovery of the vital “black boxes” is highly unlikely.

Last year aviation writer Christine Negroni published The Crash Detectives: Investigating the World’s Most Mysterious Air Disasters (Penguin Books, 2016). It hypothesizes that immediately after making a radio call to air traffic control, Captain Zaharie Ahmad Shah left the flight deck to visit the lavatory, and at the same time, the co-pilot, Fariq Abdul Hamid, inadvertently switched off the aircraft’s transponder. Also at the same time, “a rapid decompression happened near or in the cockpit,” incapacitating the absent captain.

The Crash Detectives’ hypothesis further assumes that the co-pilot donned his emergency oxygen mask, but that it failed to provide full oxygen flow because the mask or its connection was defective, or because the emergency oxygen system was improperly serviced before departure. No evidence supports these assumptions. It further assumes that this partial incapacitation allowed the co-pilot to “maintain some awareness,” but that “he was not thinking clearly,” and that in this condition, the co-pilot deliberately turned the plane 180 degrees back toward Malaysia. Then, 32 minutes after pressurization was lost, “he made yet another decision explicable only by a hypoxia-induced, half-witted state. He turned the plane north,” and continued on that heading until radar contact was lost thirty minutes later. Thereafter, he made yet another turn, to the southwest. This final turn is where the hypothesis assumes the co-pilot’s “deprived brain reached its limit.” The plane continued on that heading for another five hours, until fuel exhaustion.

This hypothesis is implausible, because it requires the assumptions that (1) the captain left the flight deck immediately after his final radio call; (2) depressurization occurred simultaneously; (3) the captain was unable to use one of the passenger masks that deploy upon loss of cabin pressure; (4) the copilot’s emergency oxygen system malfunctioned simultaneously, leaving him in a “hypoxia-induced, half-witted state,” which (5) caused him to accidentally turn off the transponder, and (6) prevented him from contacting air traffic control, but (7) allowed him to continue flying for an hour and make three radical course changes. No evidence supports any of these assumptions.

The Crash Detectives cites Helios Airways flight 522, a Boeing 737 that crashed near Athens in August, 2005, but that accident does not support its hypothesis. Helios flight 522 lost pressurization shortly after takeoff from Cyprus, and radio transmissions ceased eight minutes later. The plane continued on to Athens and entered a holding pattern under control of the automatic pilot. Greek Air Force jets intercepted it and reported that passenger masks were dangling in the cabin, the co-pilot was slumped in his seat, and the captain’s seat was empty. The 737 eventually ran out of fuel and crashed. There was actual evidence that the plane had experienced prior pressurization problems, the crew set the pressurization controls improperly, and the cabin did not pressurize after takeoff. The pilots were quickly incapacitated, and the plane flew to Athens on autopilot, with no post-incapacitation human intervention as hypothesized in The Crash Detectives.[1]

“Occam’s razor,” a well-known problem-solving principle attributed to a 13th century English philosopher, holds that among competing hypotheses the one with the fewest assumptions should be selected. The Crash Detectives’ hypothesis requires multiple assumptions without supporting facts to explain an hour-long flight, with multiple course changes, by a pilot able to control the plane, but not to communicate by radio or take other action.

The hypothesis with the fewest assumptions about Malaysia Airlines Flight 370 remains human intervention, most likely by a crew member familiar with and capable of operating the airplane’s systems and controls. That hypothesis is supported by data recovered from the captain’s personal flight simulator, which includes a flight path to the southern Indian Ocean[2]—flight 370’s ultimate destination—and no known facts contradict it.[3] Such events are exceedingly rare, but not unknown, as occurred with EgyptAir Flight 990 in October, 1999, and Germanwings Flight 9525 in March 2015.