SEPANG, Malaysia — Mohammad Mallaeibasir said his goodbyes to his childhood friend from Iran at the sprawling international airport here last March 7. Parting was easy then. Both he and his friend were teenagers with their whole lives, and presumably many reunions, ahead of them.

But the friend was a passenger aboard Malaysia Airlines Flight 370 bound for Beijing, which disappeared from ground controllers’ screens less than an hour after takeoff and veered far off course, prompting a vast search operation that, nine months later, has yet to find the jet or anyone who was on it. On Sunday night, Mr. Mallaeibasir received a message on Facebook from his friend’s mother, asking him about a recent article on the aircraft, as she continues trying to learn what happened to her son.

“If they get any answer, I think it’s better than knowing nothing,” Mr. Mallaeibasir, 19, said of the search effort in a telephone interview on Monday. “Even a bad answer is better than no answer.”

Malaysians have been confronted by many unanswered questions this year about a string of aviation disasters: the disappearance of Flight 370; the crash of another Malaysia Airlines jetliner, Flight 17, in Ukraine in July; and most recently, the disappearance of AirAsia Flight 8501 on Sunday as it flew toward Singapore from Surabaya, Indonesia. The airline is Malaysian-based, though the missing aircraft belonged to an affiliated Indonesian company.

If all of Flight 8501’s passengers have perished, that would mean the three deadliest aviation disasters of 2014 were all tied to Malaysia.

No trace of Flight 8501 had been found by late Monday night, despite two days of searching, with about 30 ships and 15 planes scouring the Java Sea among the islands of Borneo, Sumatra and Java. Bambang Soelistyo, head of the Indonesian National Search and Rescue Agency, said that the plane was probably “at the bottom of the sea” and that Indonesia did not have the necessary equipment to search properly for it underwater.

At AirAsia’s hub in Kuala Lumpur on Monday, passengers and relatives of people about to board the airline’s flights to destinations from India to Australia expressed a mix of fatalism and frustration at the lack of answers about the three aviation disasters. They said they suspected they were not being told the whole story by government officials or the news media.

Julianna Chong, 19, and her brother Jufri Aminuddin Chong, 21, were seeing their younger sister off. She was bound for Melbourne, Australia, for an extended vacation. Ms. Chong, who studies art, said she was saddened and puzzled by the accidents: “Three times,” she said. “That’s not normal.”

Her brother said: “We’re really upset about it. It could be our families.” But he added: “Things happen in waves. You can’t really control it.”

Outside the AirAsia operations office at the Kuala Lumpur airport, company employees emphasized that the missing flight was operated by an affiliated Indonesian airline that is separate from the Malaysia-based parent. “We in Malaysia are AK, they are QZ,” said one female flight attendant, referring to the code letters used for each carrier’s flights. She declined to give her name, saying that employees had been told not to speak to reporters about the missing plane.

Yet the two carriers use the same logo and fly out of the same terminal in Kuala Lumpur, where 63 of the 72 flights listed on a status board late Monday evening were AirAsia flights. Tony Fernandes, the Malaysian chief executive of the parent company, further demonstrated the close ties between the affiliates when he flew to Surabaya on Monday to meet with families of relatives after visiting the search and rescue operations center in Jakarta.

“My heart bleeds for all the relatives of my crew and our passengers,” Mr. Fernandes said on Twitter on Monday. “Nothing is more important to us.”

And to Malaysian travelers, the fact that Mr. Fernandes’s company owns only 49 percent of the Indonesian affiliate made little difference. “They are all our planes,” said Ramesh Sandra, 47, a marketing manager who was on his way to India for a religious pilgrimage.

In one breath, he said the tragedies were “beyond our control” and “God’s grace.” Then he raised questions about the airlines’ decisions to put passengers in harm’s way. Why was Flight 17 routed over a war zone in Ukraine? Why did the pilot of flight 8501 fly into bad weather?

“Three times is terrible,” Mr. Sandra said. “Life is more important than money.”

Ram Karun, 37, an engineer for a food processing plant who was also bound for India on a pilgrimage, said he could not believe what he was hearing in news reports about the three air disasters. He said he thought the government knew more than it was saying.

He was also one of a minority of passengers who were not flying on AirAsia, choosing a rival budget airline instead.

“Everyone knows something is happening, but we can’t figure it out,” he said. “We don’t know exactly what is happening.”（MICHAEL FORSYTHE）