Narrative:

Tower asked if I could accept an immediate takeoff. I acknowledged that I could and was cleared, I thought. Tower was communicating to another aircraft with similar call sign. When tower saw my aircraft take the active she canceled the takeoff clearance, I exited the runway and was informed of my error. Obviously, this was my mistake. Contributing factors, include the following: I am a low time instructor and this was my first flight with this student. Occurrence happened at nzy where military traffic uses one frequency and civil aircraft use another. Had I heard the military traffic acknowledge the tower, this would not have happened. Human factors were: I was concerned/preoccupied with the new student and the WX which was marginal. Although legal I think it would have been better not to fly in marginal conditions with a student. It was a bad example I will not repeat. To keep this from ever reoccurring, I make sure I repeat clrncs fully and give ATC sufficient opportunity/time to correct any mistakes/misreads on mine or their part. I also am more conscious of other aircraft especially when accepting midfield departures.

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Original NASA ASRS Text

Title: A PA28 INSTRUCTOR PLT WITH STUDENT TAKES THE RWY WHEN SIMPLY ASKED BY THE TWR CTLR IF THEY COULD ACCEPT AN IMMEDIATE TKOF AT NZY, CA.

Narrative: TWR ASKED IF I COULD ACCEPT AN IMMEDIATE TKOF. I ACKNOWLEDGED THAT I COULD AND WAS CLRED, I THOUGHT. TWR WAS COMMUNICATING TO ANOTHER ACFT WITH SIMILAR CALL SIGN. WHEN TWR SAW MY ACFT TAKE THE ACTIVE SHE CANCELED THE TKOF CLRNC, I EXITED THE RWY AND WAS INFORMED OF MY ERROR. OBVIOUSLY, THIS WAS MY MISTAKE. CONTRIBUTING FACTORS, INCLUDE THE FOLLOWING: I AM A LOW TIME INSTRUCTOR AND THIS WAS MY FIRST FLT WITH THIS STUDENT. OCCURRENCE HAPPENED AT NZY WHERE MIL TFC USES ONE FREQ AND CIVIL ACFT USE ANOTHER. HAD I HEARD THE MIL TFC ACKNOWLEDGE THE TWR, THIS WOULD NOT HAVE HAPPENED. HUMAN FACTORS WERE: I WAS CONCERNED/PREOCCUPIED WITH THE NEW STUDENT AND THE WX WHICH WAS MARGINAL. ALTHOUGH LEGAL I THINK IT WOULD HAVE BEEN BETTER NOT TO FLY IN MARGINAL CONDITIONS WITH A STUDENT. IT WAS A BAD EXAMPLE I WILL NOT REPEAT. TO KEEP THIS FROM EVER REOCCURRING, I MAKE SURE I REPEAT CLRNCS FULLY AND GIVE ATC SUFFICIENT OPPORTUNITY/TIME TO CORRECT ANY MISTAKES/MISREADS ON MINE OR THEIR PART. I ALSO AM MORE CONSCIOUS OF OTHER ACFT ESPECIALLY WHEN ACCEPTING MIDFIELD DEPS.

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.