Narrative:

Aircraft was holding short of taxiway a after starting and completing pre-taxi checks. ATIS was obtained. Student switched to ground frequency in order to call for taxi clearance. The frequency was monitored for about ten seconds to ensure a transmission would not be interrupted. The frequency was quiet and the student transmitted; 'bozeman tower (meaning to say ground) this is da-20 ready for taxi with information G; remaining in the pattern.' after a brief pause a transmission was heard; 'taxi runway 12 via a; verify you have information G'. After clearing left and right; student began rolling toward taxiway a and stated; 'that's correct we have G; taxi via a; da-20.' now on taxiway a ground transmitted; 'is da-20 calling ground?' instructor replied; 'affirmative; da-20.' ground replied; 'what did you want?' at this time instructor realized we had not been given clearance to taxi; stopped the plane and replied; 'we just called and got taxi clearance to 12 with G.' controller replied; 'okay; I just gave taxi clearance to aircraft Y. Da-20 taxi to 12 via alpha; say intentions.' instructor replied; '12 via a; we have G; remaining in the pattern; da-20'. After listening to the recording on liveatc.net it became apparent that the student's initial transmission was blocked by ground issuing a taxi clearance to aircraft Y. This caused us to hear only the words 'taxi runway 12 via a verify you have information G.' the cause of the problem was the instructor's failure to either verify that the transmission was for the correct aircraft or have the student do so. A recurrence of this event can be avoided by obtaining verification from ATC if ever in doubt.

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Original NASA ASRS Text

Title: Flight Instructor describes the circumstances of a missed communication with Ground Control when his student called for taxi clearance.

Narrative: Aircraft was holding short of Taxiway A after starting and completing pre-taxi checks. ATIS was obtained. Student switched to Ground frequency in order to call for taxi clearance. The frequency was monitored for about ten seconds to ensure a transmission would not be interrupted. The frequency was quiet and the student transmitted; 'Bozeman Tower (meaning to say Ground) this is DA-20 ready for taxi with information G; remaining in the pattern.' After a brief pause a transmission was heard; 'Taxi Runway 12 via A; verify you have information G'. After clearing left and right; student began rolling toward taxiway A and stated; 'That's correct we have G; taxi via A; DA-20.' Now on Taxiway A Ground transmitted; 'Is DA-20 calling ground?' Instructor replied; 'Affirmative; DA-20.' Ground replied; 'What did you want?' At this time Instructor realized we had not been given clearance to taxi; stopped the plane and replied; 'We just called and got taxi clearance to 12 with G.' Controller replied; 'Okay; I just gave taxi clearance to aircraft Y. DA-20 taxi to 12 via Alpha; say intentions.' Instructor replied; '12 via A; we have G; remaining in the pattern; DA-20'. After listening to the recording on liveATC.net it became apparent that the student's initial transmission was blocked by Ground issuing a taxi clearance to aircraft Y. This caused us to hear only the words 'taxi Runway 12 via A verify you have information G.' The cause of the problem was the instructor's failure to either verify that the transmission was for the correct aircraft or have the student do so. A recurrence of this event can be avoided by obtaining verification from ATC if ever in doubt.

Data retrieved from NASA's ASRS site as of July 2013 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.