Seven British, five Chinese and four Nepalese passengers were reported to have been killed, as were three crew members. The plane, which was headed to Lukla, a gateway to Mount Everest, was a propeller-driven Dornier owned by Sita Air, a domestic carrier.



It was the seventh fatal plane crash in Nepal since August 2010, according to the Aviation Safety Network, a research organization. Nepal is a popular trekking destination and a number of its small airports are tucked between mountains and often shrouded in fog.



An air traffic control official said the plane took off from Tribhuvan International Airport in Katmandu at 6:17 a.m. and appeared to be in trouble almost immediately.



“We noticed unusual maneuvering of the aircraft from the tower,” said the official, who spoke on condition of anonymity because he was not authorized to speak to the news media. “When asked, the pilot only managed to say it was a bird hit,” he said. “Within two seconds, the aircraft crashed.”



Ratish Chandra Lal Suman, the airport’s general manager, told The Associated Press the plane had struck a vulture.



The plane was on fire when it crashed onto a bank of the Manohara River about 500 meters southeast of the runway, according to witnesses, who said the pilot appeared to swerve to avoid a settlement.



Nepal’s aviation safety standards lag far behind the global average, according to an International Civil Aviation Organization audit released last year, which ranked it as one of the most dangerous countries for air travel in the Asia-Pacific region.



Heather Timmons reported from New Delhi.