Pilots Zaharie Ahmad Shah, 53, and Fariq Abdul Hamid were described as respectable, community-minded men.
Fariq has drawn the greatest scrutiny after the revelation that in 2011, he and another pilot invited two women boarding their aircraft to sit in the cockpit for a flight from Phuket, Thailand, to Kuala Lumpur.
During the flight, the pilots smoked and flirted, one of the women, South African Jonti Roo, said in an interview broadcast by Australia's Nine Network. The claims were backed up with numerous photos showing Roos and her friend posing in the cockpit.
Alhough initially thrilled by the experience, Roos also described it as "possibly a little bit sleazy."
Malaysia Airlines said it was shocked by the report and was investigating.
Fariq was a "good boy, a good Muslim, humble and quiet," said Ahmad Sarafi Ali Asrah, the head of a mosque near Fariq's two-story home in a middle-class neighborhood on the outskirts of Kuala Lumpur.
"I don't think he is a playboy. But I don't know about his personal life." the imam added,
He described Fariq's parents as distraught over the missing plane and said the community was solidly supporting the family with prayers.
Fariq, the son of a high-ranking civil servant in Selangor state, joined Malaysia Airlines in 2007. With 2,763 hours of flight experience, he had only recently started co-piloting the sophisticated Boeing 777.
"His father still cries when he talks about Fariq. His mother too," Ahmad Sarafi saod.
Fariq had a brush with fame when he was filmed recently by a crew from "CNN Business Traveler," and reporter Richard Quest described it as a perfect landing of a Boeing 777-200, the same model as the plane that vanished. An online tribute page to the pilots shows a photo of Fariq in the cockpit with Quest, both smiling.
Neighbor Ayop Jantan said he had heard that Fariq was engaged and planning his wedding. The eldest of five children, Fariq's professional achievements were a source of pride for his father, Ayop said.
Zaharie, the pilot of MH370, joined Malaysia Airlines in 1981 and had more than 18,000 hours of experience.
His Facebook page showed an aviation enthusiast who flew remote-controlled aircraft, posting pictures of his collection, which included a lightweight twin-engine helicopter and an amphibious aircraft.
Born in northern Penang state, the captain and grandfather was an enthusiastic handyman and proud home cook. As part of what he called "community service," he had posted several YouTube videos including how to make air conditioners more efficient to cut electricity bills, how to waterproof window panes, and how to repair a refrigerator icemaker.