Instructor pilot with a student does not hear hold short instructions from tower and makes an unauth...

Attributes
ACN	420390
Time
Date	199811
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ffz airport : ffz
State Reference	AZ
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : instructional
Make Model Name	PA-28 Cherokee/Archer II/Dakota/Pillan/Warrior
Flight Phase	climbout : takeoff
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot instruction : instructor
Qualification	pilot : cfi pilot : instrument pilot : commercial
Experience	flight time last 90 days : 200 flight time total : 1400 flight time type : 500
ASRS Report	420390
Person 2
Affiliation	Other
Function	flight crew : single pilot instruction : trainee
Qualification	pilot : student
Events
Anomaly	incursion : runway non adherence : far non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Requested takeoff clearance from tower. Radio traffic was very busy at the time. Tower may have issued a hold short instruction which, due to garbling of the transmission, was misinterped, thinking we had a takeoff clearance. The hold short instruction was not read back. Tower later said we were told to 'hold short' and we replied we did not read back a 'hold short,' indicating that we never realized the instruction was given.

Original NASA ASRS Text

Title: INSTRUCTOR PLT WITH A STUDENT DOES NOT HEAR HOLD SHORT INSTRUCTIONS FROM TWR AND MAKES AN UNAUTH TKOF.

Narrative: REQUESTED TKOF CLRNC FROM TWR. RADIO TFC WAS VERY BUSY AT THE TIME. TWR MAY HAVE ISSUED A HOLD SHORT INSTRUCTION WHICH, DUE TO GARBLING OF THE XMISSION, WAS MISINTERPED, THINKING WE HAD A TKOF CLRNC. THE HOLD SHORT INSTRUCTION WAS NOT READ BACK. TWR LATER SAID WE WERE TOLD TO 'HOLD SHORT' AND WE REPLIED WE DID NOT READ BACK A 'HOLD SHORT,' INDICATING THAT WE NEVER REALIZED THE INSTRUCTION WAS GIVEN.

Data retrieved from NASA's ASRS site as of July 2007 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.

Instructor pilot with a student does not hear hold short instructions from tower and makes an unauthorized takeoff.