Federal investigators are examining whether an air traffic controller at LaGuardia Airport stepped away from his console to use an emergency phone just before the deadly collision between an Air Canada Express jet and a fire truck on March 22. The National Transportation Safety Board is pursuing multiple avenues of inquiry, including staffing levels and communication protocols, as they reconstruct the events leading to the deaths of two pilots.

LaGuardia's standard overnight shift requires two controllers, but investigators are scrutinizing whether a third controller had to leave his post during the critical moments before impact. The fire truck was responding to an emergency call from a United Airlines plane reporting a strange odor on board. Investigators are also analyzing the positioning of the lead fire truck near the runway, the communication devices used by drivers, and whether weather conditions and light pollution played a role in the accident.

The crash marked LaGuardia's first deadly accident in more than 30 years. Investigators are reviewing cockpit voice recordings, interviewing controllers and firefighters, and examining the fire truck's electronic data recorder. The NTSB is particularly focused on whether the lead truck's operators could have seen the oncoming plane given the awkward approach angle and whether they missed critical instructions from the control tower.