Narrative:

During the preparation for an early morning flight, I started the airplane after a standard preflight, got the AWOS and tried to contact mccollum ground on 119.0. As I could not get any answer, I switched to the tower frequency 125.9 and tried again. The official time at which the tower opens is XX00Z (in the airport facility directory) or XA00 am local time, but I knew this was wrong as I had operated from the field a few days ago between XA00 am and XB00 am and had communicated with other airplanes on the CTAF (125.90). Unable to get any answer from the tower (and assuming the radio worked fine as I just got the AWOS), I proceeded as if the field was uncontrolled, taxied to the run-up pad, did the checklists for pre-takeoff, called my intentions on the CTAF frequency, made sure nobody was in the pattern and took off. Arriving at 1000 ft AGL, I heard the tower calling me -- it did not take long to realize what had happened. Although I tried to radio back, they could not hear me until 15-20 seconds later. They asked me my intentions and things went back to normal from then on. I called the controller at my next stop to apologize. It turned out that they could not hear me and I could not hear them either while they were trying to call me prior to the takeoff. Prior to the flight, the aircraft had been sitting in the rain for 48 hours, and the radio behavior surprised me as this was not a stuck microphone, low volume or other classic VHF malfunction. The problem was caused by poor judgement from myself (relying on electronic equipment to determine the tower was closed, from an aircraft that had been exposed to the rain for 2 days). The contributing factors were the lack of accurate information for the tower operating hours in the airport facility directory, and a still unexplained malfunction in the aircraft's radio equipment (the radios worked fine after the departure and no further problem arose from then on).

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Original NASA ASRS Text

Title: PLT OF SMA UNABLE TO CONTACT TWR BELIEVES IT IS CLOSED AND TAXIES AND DEPARTS WITHOUT CONTACT.

Narrative: DURING THE PREPARATION FOR AN EARLY MORNING FLT, I STARTED THE AIRPLANE AFTER A STANDARD PREFLT, GOT THE AWOS AND TRIED TO CONTACT MCCOLLUM GND ON 119.0. AS I COULD NOT GET ANY ANSWER, I SWITCHED TO THE TWR FREQ 125.9 AND TRIED AGAIN. THE OFFICIAL TIME AT WHICH THE TWR OPENS IS XX00Z (IN THE ARPT FACILITY DIRECTORY) OR XA00 AM LCL TIME, BUT I KNEW THIS WAS WRONG AS I HAD OPERATED FROM THE FIELD A FEW DAYS AGO BTWN XA00 AM AND XB00 AM AND HAD COMMUNICATED WITH OTHER AIRPLANES ON THE CTAF (125.90). UNABLE TO GET ANY ANSWER FROM THE TWR (AND ASSUMING THE RADIO WORKED FINE AS I JUST GOT THE AWOS), I PROCEEDED AS IF THE FIELD WAS UNCTLED, TAXIED TO THE RUN-UP PAD, DID THE CHKLISTS FOR PRE-TKOF, CALLED MY INTENTIONS ON THE CTAF FREQ, MADE SURE NOBODY WAS IN THE PATTERN AND TOOK OFF. ARRIVING AT 1000 FT AGL, I HEARD THE TWR CALLING ME -- IT DID NOT TAKE LONG TO REALIZE WHAT HAD HAPPENED. ALTHOUGH I TRIED TO RADIO BACK, THEY COULD NOT HEAR ME UNTIL 15-20 SECONDS LATER. THEY ASKED ME MY INTENTIONS AND THINGS WENT BACK TO NORMAL FROM THEN ON. I CALLED THE CTLR AT MY NEXT STOP TO APOLOGIZE. IT TURNED OUT THAT THEY COULD NOT HEAR ME AND I COULD NOT HEAR THEM EITHER WHILE THEY WERE TRYING TO CALL ME PRIOR TO THE TKOF. PRIOR TO THE FLT, THE ACFT HAD BEEN SITTING IN THE RAIN FOR 48 HRS, AND THE RADIO BEHAVIOR SURPRISED ME AS THIS WAS NOT A STUCK MIKE, LOW VOLUME OR OTHER CLASSIC VHF MALFUNCTION. THE PROB WAS CAUSED BY POOR JUDGEMENT FROM MYSELF (RELYING ON ELECTRONIC EQUIP TO DETERMINE THE TWR WAS CLOSED, FROM AN ACFT THAT HAD BEEN EXPOSED TO THE RAIN FOR 2 DAYS). THE CONTRIBUTING FACTORS WERE THE LACK OF ACCURATE INFO FOR THE TWR OPERATING HRS IN THE ARPT FACILITY DIRECTORY, AND A STILL UNEXPLAINED MALFUNCTION IN THE ACFT'S RADIO EQUIP (THE RADIOS WORKED FINE AFTER THE DEP AND NO FURTHER PROB AROSE FROM THEN ON).

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.