FlyDubai Flight 1073 was carrying four pilots on its journey from Dubai to Tel Aviv. After a co-pilot stabbed the captain, two pilots who were seated in the cabin took control and safely landed the Boeing 737 Max 8 jet in Saudi Arabia.

Why were there extra pilots on board?

For the most part, airlines do not intentionally staff shorter flights with a backup flight crew simply as a precaution, because paying two sets of pilots is expensive. However, pilots routinely hitch rides on flights they are not operating — a practice known in the industry as “deadheading” — to position themselves where they are needed next.

In a statement, FlyDubai confirmed that “on-duty FlyDubai crew traveling on the flight” safely landed the plane. Because deadheading pilots are on company assignment, they are technically considered on duty, receive pay and are forbidden to consume alcohol. Wearing a uniform is optional.

John Cox, a retired airline captain and aviation safety consultant, said the extra pilots were most likely being moved to where they needed to be for their next assigned flight. “We move pilots all around the world,” Mr. Cox said.

Mr. Cox was skeptical that an airline would deploy additional pilots on a relatively short flight simply as routine insurance against potential delays. “Pilots are expensive,” he said. “They are highly trained, but also highly compensated. From a business standpoint, you want the right number of pilots at the right place at the right time. You don’t want to be paying for more than you need.”

Another possibility is that FlyDubai needed a second crew to fly the plane on its return leg to Dubai because the operating crew would have exceeded its legal duty limits and required mandatory rest, aviation industry experts said.

The airline declined to answer questions about the flight, including about the presence of the extra pilots on board the flight to Tel Aviv.

While a 3.5-hour flight would not normally require extra pilots, analysts said regional conditions have created unique scheduling demands. Major Persian Gulf-based carriers have repeatedly suspended, canceled or rerouted flights as conflicts in the region have flared.

A pilot’s regulated working time isn’t just hours in the air — it begins when the pilot reports for duty at the airport, incorporating taxi time, delays and ground turnarounds. Unforeseen detours or holding patterns can cause a primary crew to exceed its daily limit, known as timing out.

Richard Levy, a retired airline captain, praised the heroism of the crew and passengers aboard FlyDubai Flight 1073. He said it was remarkable that the wounded captain managed to unlock the door and send an emergency signal while under attack, and that the backup pilots managed to land the plane.

Mr. Levy added that it was astonishing that the aircraft stayed intact. “The rudder was ripped off,” he said. “It’s a miracle that the plane was still flyable.”

Sally Leivesley, an aviation security expert, said that having a backup crew on board shorter flights could make sense given regional tensions. In light of the ballistic missiles being fired in the region, “you really do not want your plane in that vicinity,” so flights can be delayed until the danger is cleared, Dr. Leivesley noted.

Dr. Leivesley said she saw no signs that the off-duty pilots were on board Flight 1073 because of a specific security warning. Passengers responded to the cockpit attack before the off-duty pilots did, she noted, reasoning that if the pilots had expected it, they would have reacted ahead of the passengers who rushed the flight deck.

She estimated that it would have taken only about five more seconds before the plane passed the point where it could no longer be pulled out of its descent and recovery would have been impossible.

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