"We're not taking any chances," said Valerie Wunder, a spokeswoman for US Airways.
In a statement, the Air Transport Association, which represents 19 US airlines, said: "Decisions to divert aircraft for security reasons are made for a wide variety of reasons. While the reasons for these decisions will vary, the common factor is the overarching importance of assuring the safety of our passengers and crews."
A sampling of passengers last night at Logan Airport found a sense of resignation that such occurrences are part of traveling in this era of terrorism.
"I think it probably is becoming a way of life, probably more so because you're getting people calling in threats," said Helen Connaughton, 29, a Boston resident who was going to visit family in Ireland. "You can't distinguish between what's serious and not."
Allen Costa, 21, of Boston, who was also flying to Ireland, said flight diversions would taper off.
"I don't think planes being diverted is going to be the norm," he said. "There aren't that many legitimate threats that necessitate those precautions. I think things will settle back down again."
In any case, passengers said they would keep flying. "It's going to be there in the back of your mind, but I wouldn't let it dictate whether you fly or not," said Fiona O'Donnell, 30, of Galway, Ireland. "I don't even think like that. I just go and hope to God I get there. It wouldn't stop me from flying."