
Federal safety officials are investigating an American Airlines flight that caught fire on the Denver International Airport tarmac on Thursday.
The National Transportation Safety Board is sending two investigators to the scene, who will begin the long process of trying to determine what caused the incident. The investigators will examine the aircraft, conduct interviews with witnesses and crew, and obtain other data, NTSB officials wrote in an email to CPR News.
A preliminary report will be available in 30 days. But the final report, which will detail the probable cause of the event, will take a year or longer to complete.
In the meantime, here’s what we know about the Thursday incident.
4:52 p.m.
American Airlines flight 1006 took off from the Colorado Springs Airport destined for Dallas-Fort Worth International Airport. The Boeing 737 was manufactured in 2012, records show, and was carrying 172 passengers and six crew members.
5:14 p.m.
The flight diverted to Denver International Airport about 20 minutes after takeoff, according to FlightAware. The crew had reported engine vibrations, the Federal Aviation Administration said.
“Just to verify, not an emergency, correct?” an air traffic controller asked the airplane’s crew, per a recording posted on LiveATC.net.
“We just have a high engine vibration, so we are cruising slower than normal,” one of the crew members replied.
It’s not clear why the plane did not return to the Colorado Springs airport; an airport spokesman there referred a CPR News question about the diversion to American Airlines, which did not reply to a request for comment on Friday.

Denver International Airport spokesman Michael Konopasek also deferred to the airline, but added that the airport’s operations and safety teams “always stand ready when there’s diversions.”
“We're extremely proud of the teams that we have here and how quickly they jump into action when they're needed,” he said. “And we saw that yesterday.”
5:55 p.m.
The flight landed at Denver International Airport, per FlightAware. The plane was taxiing to gate C38 when it caught fire, the FAA said.
“Mayday, mayday, mayday, mayday,” someone says over the radio in another recording published on LiveATC.net. “Engine fire.”
Numerous videos on social media from airport passengers show the fire burning around and below one of the jet's turbine engines under the right wing. It's unclear what caused the fire. American Airlines called it "an engine-related issue."
"We thank our crew members, DEN team and first responders for their quick and decisive action with the safety of everyone on board and on the ground as the priority," an American Airlines spokesperson said in a statement Thursday evening.
All of the crew and passengers were evacuated and at least a dozen people were sent to hospitals in the area with minor injuries, an airport spokesperson said.
The airport continued to operate normally outside of gate C38, officials said, which was expected to reopen on Friday.
CPR’s Alejandro Alonso Galva contributed to this report.