The “Triple Seven,” as it often called, has all but replaced the 747 because it is cheaper to operate and can fly up to 16 hours without stopping to refuel. It also has one of the industry’s best safety records, with only two serious accidents in the 19 years it has been in service.

Malaysia Airlines, the nation’s state-run carrier, began using the Boeing 777 in 1997 and eventually had 15 in its fleet. One of them, the 404th model to roll off Boeing’s assembly line in Everett, Wash., was delivered to the airline in May 2002 and registered with tail number 9M-MRO. This was the plane used for Flight 370 that has disappeared.

Malaysia Airlines has said the jet has been involved in only one previous safety incident. On Aug. 9, 2012, the tip of one of its wings broke off after it clipped the tail of a China Eastern Airlines Airbus A340 while taxiing at Shanghai Pudong International Airport. No one was hurt. Boeing said it sent a team of engineers and mechanics to remove and replace the damaged wing sections, and returned the plane to service after testing.

Boeing recommends a light maintenance inspection of the 777 after about 500 hours of flight time. Known as an “A check,” the inspection usually is conducted in a hangar by a team of about 15 engineers working about 10 hours, often overnight. Malaysia Airlines said the jet’s last A check took place on Feb. 23, and uncovered no problems.

By the time it pulled up to the gate at Kuala Lumpur International Airport on March 8, the plane had completed more than 7,500 flights and clocked over 53,400 hours in the air, according to Flightglobal, a news and data service for the aviation sector. That put it well within the average economic life of 23 years for a wide-body passenger jet.

In other words, there was little to distinguish this plane from the roughly 1,170 other Boeing 777s in use. That is why it is so crucial to determine if the plane’s disappearance was due to any malfunction or defect related to its design, build or engineering. “The industry does not like uncertainty,” said Mark Rosenker, a former chairman of the National Transportation Safety Board. “We will find out what happened.”

Boarding

As they stepped onto the plane, the 227 passengers of Flight 370 were greeted by the flight attendants, four women in sarong kebayas and six men in gray three-piece suits. Some distributed hand towels, juice and newspapers in business class; others helped those in economy find their seats.