By the time the student pilot and instructor taxiing in the Cessna 172 had switched from ground control to the tower frequency for their takeoff clearance, takeoff instructions were already being issued by the tower controller.
The occupants of the aircraft, which was No. 1 for departure on Runway 9L, read back the clearance and began to taxi onto the runway.
In nearly triggering a mishap, the occupants of the taxiing aircraft had become victims of the unlikely combination of a technical glitch (without its usual telltale indications) and their own logical—but incorrect—assumptions about the situation on the ground at their Florida airport.
This they came to realize after listening to an audio recording. It demonstrated that their readback of the takeoff clearance had been blocked by a transmission from another aircraft. But, “At the time we were giving the clearance back on our radio, we did not hear any interference in the transmission,” the ASRS report noted, explaining why they had remained unaware that their transmission had been stepped on.
As for their erroneous assumption: When tuning in the tower frequency and hearing a takeoff clearance already in the process of being issued, the instructor and student had been certain that it must be for them because they were “number one” for takeoff—a conclusion reinforced by the tower’s silence.
“Since we were first for departure and there was no indication of negative clearance we then started to cross hold short line,” said their joint ASRS report.
Recall, however, that this event occurred at a busy multiple-runway airport where any uncertainty should be clarified before proceeding—a practice to follow at any airport.
Follow it when airborne as well. It’s not uncommon on a congested air traffic control frequency for a flight crew to query ATC whether instructions were for them, and for a controller to inquire of a crew, “Did you copy?”
All the back-and-forth takes time and may make other pilots in need of attention impatient, but it’s still preferable to an incursion or worse resulting from a chain of missed opportunities to keep everyone safe.