Narrative:

Today, I departed IFR from an uncontrolled airport for practice instrument approachs. Due to the airspace restrs currently in place (wtc and pentagon), we used a cell phone (as we held short of the runway) to call minneapolis approach for our IFR clearance (normally, we depart VFR and receive clearance airborne). The person I spoke to indicated that she could not release us yet as she had traffic on a nearby approach. However she said that she could give us our clearance and to hold for release. I copied our clearance and then she started giving us a clearance void time. As she started to give me the clearance void time, a nearby B25 started its run-up creating a great deal of noise and interference to my phone. Therefore I had to ask the controller to read the void times 3 times. I repeated back to her what I had heard (valid at XA31Z void at XA33Z). I said that I would report airborne. At this point we departed runway 16 (sgs) and contacted minneapolis approach on 121.2 at which time the controller indicated that we were airborne 2 mins early. This was a surprise to me as I had never heard a current time issued when I received my void time. I incorrectly assumed that she had given us a 2 min window upon which to depart immediately. Also, when on the ground on my cell phone, I mentioned that I could not hear what was being said due to the noise of the B25 behind us. When I read back what I heard, there was not any mention of the current time to clarify and point out that the clearance was not yet valid. Contributing factors: noise from B25, lack of understanding between myself and controller, and busy airspace and flight restrs.

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Original NASA ASRS Text

Title: C172 PLT, CONDUCTING IFR TRAINING, MISUNDERSTANDS CTLR'S CLRNC INSTRUCTIONS AND DEPARTS AN UNCTLED ARPT BEFORE BEING RELEASED.

Narrative: TODAY, I DEPARTED IFR FROM AN UNCTLED ARPT FOR PRACTICE INST APCHS. DUE TO THE AIRSPACE RESTRS CURRENTLY IN PLACE (WTC AND PENTAGON), WE USED A CELL PHONE (AS WE HELD SHORT OF THE RWY) TO CALL MINNEAPOLIS APCH FOR OUR IFR CLRNC (NORMALLY, WE DEPART VFR AND RECEIVE CLRNC AIRBORNE). THE PERSON I SPOKE TO INDICATED THAT SHE COULD NOT RELEASE US YET AS SHE HAD TFC ON A NEARBY APCH. HOWEVER SHE SAID THAT SHE COULD GIVE US OUR CLRNC AND TO HOLD FOR RELEASE. I COPIED OUR CLRNC AND THEN SHE STARTED GIVING US A CLRNC VOID TIME. AS SHE STARTED TO GIVE ME THE CLRNC VOID TIME, A NEARBY B25 STARTED ITS RUN-UP CREATING A GREAT DEAL OF NOISE AND INTERFERENCE TO MY PHONE. THEREFORE I HAD TO ASK THE CTLR TO READ THE VOID TIMES 3 TIMES. I REPEATED BACK TO HER WHAT I HAD HEARD (VALID AT XA31Z VOID AT XA33Z). I SAID THAT I WOULD RPT AIRBORNE. AT THIS POINT WE DEPARTED RWY 16 (SGS) AND CONTACTED MINNEAPOLIS APCH ON 121.2 AT WHICH TIME THE CTLR INDICATED THAT WE WERE AIRBORNE 2 MINS EARLY. THIS WAS A SURPRISE TO ME AS I HAD NEVER HEARD A CURRENT TIME ISSUED WHEN I RECEIVED MY VOID TIME. I INCORRECTLY ASSUMED THAT SHE HAD GIVEN US A 2 MIN WINDOW UPON WHICH TO DEPART IMMEDIATELY. ALSO, WHEN ON THE GND ON MY CELL PHONE, I MENTIONED THAT I COULD NOT HEAR WHAT WAS BEING SAID DUE TO THE NOISE OF THE B25 BEHIND US. WHEN I READ BACK WHAT I HEARD, THERE WAS NOT ANY MENTION OF THE CURRENT TIME TO CLARIFY AND POINT OUT THAT THE CLRNC WAS NOT YET VALID. CONTRIBUTING FACTORS: NOISE FROM B25, LACK OF UNDERSTANDING BTWN MYSELF AND CTLR, AND BUSY AIRSPACE AND FLT RESTRS.

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.