The Federal Aviation Administration is investigating whether a United Airlines flight emergency distracted an air traffic controller during a fatal runway collision at LaGuardia Airport. Two controllers were working the midnight shift when a United Airlines jet reported a foul odor sickening flight attendants, prompting fire truck deployment.

As one controller cleared the fire truck to cross a major runway, an Air Canada jet was landing on the same runway. The aircraft crashed headlong into the fire truck, killing both pilots and injuring passengers. The controllers were working two positions simultaneously, reflecting typical overnight staffing levels at the airport.

National Transportation Safety Board Chair Jennifer Homendy said the midnight shift typically runs from 10:30 p.m. to 6 a.m., but investigators haven't determined how long the controllers had been on duty when the 11:37 p.m. accident occurred. Two additional controllers were in the building but not in the control room at the time.