I was once on a flight over Africa that Lt. Col. Alexander Vindman might think was "hijacked."

Vindman is the National Security Council expert on Ukraine who lit the fuse of impeachment that will detonate under President Trump. He testified Tuesday that the president's July 25 phone call with Ukrainian President Volodymyr Zelensky realized his "worst fear" that, as the Wall Street Journal put it, "policy with Ukraine was being hijacked in an effort to personally benefit Mr. Trump."

The hijacking metaphor is widely used, by the Washington Post and Los Angeles Times as well as the Wall Street Journal, for example. But is it apt? Isn't a hijack what happens when control of a plane is seized improperly from authorized pilots? Can a plane be hijacked by its own captain? Isn't he the person to make decisions about the course of the vessel under his command?

As a college student in the late 1970s, I was on a plane that was deliberately steered off course by its captain. And it was for my benefit.

The flight was heading north from Khartoum to Athens, which took it along the River Nile across the Sahara, over Cairo, and thence over the Mediterranean Sea to Greece.

In those pre-Sept. 11 days, cockpit doors were flimsy flaps and were, in any case, often left open. It was not remotely unusual for passengers to be invited to the cockpit to talk with the pilots and get a load of the great view through the windshield, which was vastly superior to the cramped vista available through portholes along the fuselage.

The captain of my flight was an Australian friend, and he invited me and my traveling companion to the cockpit shortly before we were due to pass over Abu Simbel in Upper Egypt. He was a relaxed fellow, not a stickler for rules, and thus typical of a caste of fliers who came of age in the Second World War and the decade after it.

"Let's get a better look, shall we," he said, banking the Boeing 707 and its 150 passengers over to the left so we could all get a clearer view of the 13th century B.C. site 30,000 feet below. There, looking out over Lake Nasser, were the four vast seated statues of Pharaoh Ramses II. I gazed down through the windshield over the captain's left shoulder as the airliner gradually arced off course westward.

"Oops, we'd better not go too far off line," said our cockpit host after perhaps a minute. Then he corrected course, banked right, and returned to his northward track. We returned to our seats and celebrated with preprandial champagne. A couple of hours later, we landed on time at our destination on the other side of the Aegean.

If the airline's senior officials had heard of the captain's detour, they would probably have thought it inappropriate and might well have put a note on his file, perhaps even have reprimanded him. But I doubt they'd have fired him.

Which brings me to Trump steering his administration's Ukraine policy away from what was generally understood to be its proper course. He pretty clearly sought foreign help to get dirt on a political opponent. But as the chief executive, he is the person who, more than anyone else, is responsible for charting the course his administration takes.

Witnesses at the impeachment hearings, and Trump's critics, excoriate him for parting from the "interagency consensus," but that is something he is supposed to impose or change as he deems fit. It is not something he is obliged to follow.

My comparison with a brief diversion of an airplane will doubtless be thought flippant. Guilty as charged! Yes, it's flippant and not remotely comparable in importance to changing foreign policy for personal advantage. But it does point to a problem facing those making the case against Trump on policy grounds. It's largely his policy to make.

He may not use extortion or bribery, which is the offense that Democrats appear to have poll-tested for their chief accusation. But even witnesses selected by impeachment Chairman Adam Schiff say they did not see anything in Trump's actions on Ukraine that amounted to those crimes.

All the money appropriated by Congress to aid Ukraine was paid on schedule by the end of the fiscal year; the plane reverted to its course and landed on time in Kyiv.

Perhaps a note needs to be put on the captain's file. That, like a decision that he should be sacked, is entirely political.