Flight instructor and local controller reported the instructor's flight departed without clearance w...

Attributes
ACN	1767378
Time
Date	202010
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft High Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	Takeoff
Aircraft 2
Make Model Name	Small Aircraft High Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	Landing
Flight Plan	IFR
Person 1
Function	Pilot Not Flying Instructor
Qualification	Flight Crew Instrument Flight Crew Flight Instructor Flight Crew Commercial Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 560 Flight Crew Type 536
Person 2
Function	Local
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 6
Events
Anomaly	ATC Issue All Types Deviation - Procedural Clearance Ground Incursion Runway

Narrative:

I was conducting a flight training event with my student pilot. We just returned to the airport to practice performance takeoff and landings. We had just made a full stop - taxi back. We called holding short that we were ready for touch and goes. We were told to hold short for landing traffic. Several planes land and depart. Both my student and I hear what we believe to be our abbreviated tail number being cleared for takeoff. We read back cleared for takeoff instructions; finish final items on the checklist; and take the runway. On our takeoff roll we hear tower ask who is on the runway and I respond with our tail number. Tower then advises to either exit the runway or begin our roll. We were already on the roll; so we continued the takeoff. After our lap in the pattern we terminate the training flight and contact the ATC number. I believe I heard our tail number and believed it was a takeoff clearance. However; due to a high volume of traffic the morning of the event due to a lengthy tfr that lasted most of the day; there was a lot of training and jet traffic. I could have heard a similar call sign and my student could have stepped on the intended recipient of the ATC instruction. I know when there is a high volume of traffic waiting to arrive and depart it could be best to use my full tail number to lessen confusion; and take extra measures to ensure all radio communications are properly received and copied.

Original NASA ASRS Text

Title: Flight Instructor and Local Controller reported the instructor's flight departed without clearance with traffic on very short final after mistakenly taking another aircraft's clearance for takeoff.

Narrative: I was conducting a flight training event with my student pilot. We just returned to the airport to practice performance takeoff and landings. We had just made a full stop - taxi back. We called holding short that we were ready for touch and goes. We were told to hold short for landing traffic. Several planes land and depart. Both my student and I hear what we believe to be our abbreviated tail number being cleared for takeoff. We read back cleared for takeoff instructions; finish final items on the checklist; and take the runway. On our takeoff roll we hear Tower ask who is on the runway and I respond with our tail number. Tower then advises to either exit the runway or begin our roll. We were already on the roll; so we continued the takeoff. After our lap in the pattern we terminate the training flight and contact the ATC number. I believe I heard our tail number and believed it was a takeoff clearance. However; due to a high volume of traffic the morning of the event due to a lengthy TFR that lasted most of the day; there was a lot of training and jet traffic. I could have heard a similar call sign and my student could have stepped on the intended recipient of the ATC instruction. I know when there is a high volume of traffic waiting to arrive and depart it could be best to use my full tail number to lessen confusion; and take extra measures to ensure all radio communications are properly received and copied.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Flight instructor and local controller reported the instructor's flight departed without clearance with traffic on very short final after mistakenly taking another aircraft's clearance for takeoff.