NTSB investigators released their initial findings after examining the wreckage and the plane's data recorders.

Federal transportation investigators on Tuesday pointed to two key areas under scrutiny in Sunday's deadly runway collision at LaGuardia Airport: The fire truck involved was not equipped with a transponder and only two air traffic controllers were on duty at the time.

Investigators are still working to answer critical questions about air traffic control roles on the night an Air Canada flight hit a fire truck.

Investigators found that a safety system designed to alert air traffic control of impending collisions didn't activate before the Air Canada crash.

NTSB Chair Jennifer Homendy says investigators have “conflicting information” about who was performing ground control duties. She also revealed analysis shows the ASDE-X system did not issue an alert due to the close proximity of vehicles merging,