Shortly after midnight on March 8, 2014, a Boeing 777 carrying 227 passengers and 12 crew members left Kuala Lumpur Airport in Malaysia on what was supposed to be a routine, five-and-a-half-hour flight to Beijing. An hour later, it dropped off air traffic control screens and was never sighted again.

In the following days, dozens of planes and ships from multiple countries searched hundreds of miles for MH370, but found nothing. In an age of sophisticated technology and high-speed communication, the plane and all of its passengers vanished without a trace. Was it murder-suicide by one of the pilots, as has been speculated?

First Officer Fariq Hamid was 27 years old and engaged to be married in a few months. Flight 370 was his last training flight before he was fully certified. By all accounts, he was actually flying the plane while Captain Zaharie Ahmad Shah was the Pilot in Charge (PIC).

Captain Zaharie—it’s customary in that part of the world for a man’s surname to be noted first—was 53, married 30 years, with three adult children. He has received more attention because at the time of the flight, his wife had moved out of the family’s main house and was living in a second house. Also, he was in charge of radio communication, which ceased for no apparent reason after an hour. In addition, he spent many of his off-hours on a flight simulator program, and afterward, police found on it the exact route MH370 is thought to have taken.

Many suicides—especially adult suicides—are planned. For a pilot intent on suicide, simulating the flight could be an element in the planning process.

There are other reasons to consider pilot suicide. Based on radar pings from the plane on its final flight, a British aerospace engineer determined that it took off as scheduled from Kuala Lumpur, disappeared from radar screens over the South China Sea, and shortly thereafter made an abrupt U-turn and continued past Indonesia toward the Indian Ocean. At one point, it circled over an area of the ocean for 20 minutes before continuing for at least five hours, after which there were no further pings. This means the plane had to be pilot-controlled, because it would be impossible to change direction and fly a different route unless it was manually operated.

If Flight 370 made an abrupt U-turn, stayed in the air for hours afterward, and was in a holding pattern at one time, this supports the notion of suicide because many people are ambivalent about killing themselves. They don’t want to die, but they also don’t want to live. It’s possible that Captain Zaharie spent all that time trying to decide. He probably had a fear of dying, like most people, and buying time was the way he worked up the nerve to kill himself. Alternatively, he waited until the plane ran out of fuel, and the decision was no longer in his hands.

That raises the question of murder-suicide. Most murder-suicides fall into one of four categories.[1] The most common one is when a husband shoots his chronically ill wife to take her out of her misery before he shoots himself. To others, it’s murder, but to him, it’s a mercy killing.

Maybe the reason the plane crashed in the ocean was that the pilot didn’t want to kill anyone on land. That’s a form of compassion. Also, if the captain locked his copilot out of the cockpit, then depressurized the cabin so that everyone else died of hypoxia, that would have been a compassionate way to kill someone. They gradually fall asleep without coughing, choking, or experiencing any pain, and never wake up.

All of that said, there are reasons to doubt pilot suicide preceded by murder. According to Florence de Changy, a French journalist based in Hong Kong who has written about the disappearance of MH370, it’s not unusual for couples in Malaysia who have multiple residences to live separately. As for the flight simulator, it had other flights on it, too, not just the one. In addition, blaming the pilot, she says, is too simple. It exonerates the Malaysian government, which owns and operates Malaysia Airlines, the plane’s manufacturer (Boeing), and the maker of the engine (Rolls-Royce) of any responsibility.[2]

De Changy believes that there has been a cover-up either to prevent technological failures from being exposed or government secrets from being known. She might be right. No one has publicly verified where the flight path on Captain Zaharie’s computer program ended. A longtime American Airlines pilot who flew Boeing 777s to Indonesia for many years told me that one of the first things a person does in any flight simulator program is enter the destination. You can’t just type “middle of the ocean.” A person can enter coordinates, but no one has said publicly that that was the case here.

In the same vein, a flaperon, allegedly from the right wing of MH370, washed up on a beach in the Indian Ocean a year after the plane disappeared, but it has never been presented as public evidence. Moreover, the ID plate with the serial number was missing. Also, it’s unlikely that any heavy part could float all that time without sinking.

Twelve years after Flight MH370 vanished, what happened to it remains a mystery. Maybe it was murder-suicide; maybe it wasn’t. With each passing year, the odds of knowing seem less certain.