Nine seconds. That’s all the time a LaGuardia air traffic controller had to stop a fire truck from crossing a runway — with an Air Canada jet already on the ground.The deadliest collision at LaGuardia Airport in more than three decades unfolded in under three minutes — a blur of overlapping emergencies, blocked radio transmissions, and a stop order that came too late.Federal investigators have now reconstructed almost every second of what happened, and the picture is damning.What the timeline reveals is that the collision was the final link in a chain that had been forming for nearly an hour. At the center of it all is one question that remains unanswered: Did the crew of the fire truck ever hear the order to stop?

Long before Air Canada Express Flight 8486 began its final descent, the LaGuardia control tower was already stretched thin.United Airlines Flight 2384, bound for Chicago, had been sitting on the tarmac for over two hours when it aborted its first takeoff attempt at 10:40 p.m. It then aborted a second attempt roughly 40 minutes later.At 11:31 p.m. — just minutes before the collision — the United flight declared an emergency, reporting that an onboard odor had made members of the flight crew ill and requesting an immediate gate assignment.Four minutes later, it was assigned a gate and told to wait for emergency responders. That unfolding crisis meant air traffic controllers were already managing an active emergency when the Air Canada jet began its approach.ccording to the National Transportation Safety Board, what followed was a timeline in which every second counted and not enough remained.