Narrative:

After an easy trip the day before, we were on our final leg dfw to mem, a short flight scheduled for 53 mins en route. We had arrived from mem that am. I had gone to bed for 4 hours, getting up early to see friends in dallas. Showed for pickup at the hotel at XX00 for a scheduled XY35 departure to mem. Preflight, start-up, and taxi were normal. As a crew, we were surprised by the light activity on the busiest travel day of the yr. As we approached the departure end of runway 35L, I, the first officer, acknowledged a 'cleared at the approach end of runway 35L, position and hold on runway 35L.' as the first officer, I then cleared the arrival path to the right visually and then looked down to put away my airport diagram. As I was putting away the chart, we heard our company aircraft en route to ind call for WX over the wrong frequency (tower frequency, which we were on). We were embarrassed for the company pilot talking on the wrong frequency. As I looked up, the captain advanced the throttles, and we began the takeoff roll. During the takeoff, the tower asked the captain to call when he got to his final destination. I asked him, 'were we cleared for takeoff?' we had just made a takeoff without clearance! Looking back, I wondered how we could have done this. My conclusions: I was tired from lack of sleep and not as alert as I normally am. The communication by our company over the tower frequency took us out of our normal flow. I didn't question the captain's advancing the throttles, even though I hadn't heard a takeoff clearance. I assumed if he was advancing the throttles, we must have been cleared.

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Original NASA ASRS Text

Title: WDB DEPARTS WITHOUT TKOF CLRNC.

Narrative: AFTER AN EASY TRIP THE DAY BEFORE, WE WERE ON OUR FINAL LEG DFW TO MEM, A SHORT FLT SCHEDULED FOR 53 MINS ENRTE. WE HAD ARRIVED FROM MEM THAT AM. I HAD GONE TO BED FOR 4 HRS, GETTING UP EARLY TO SEE FRIENDS IN DALLAS. SHOWED FOR PICKUP AT THE HOTEL AT XX00 FOR A SCHEDULED XY35 DEP TO MEM. PREFLT, START-UP, AND TAXI WERE NORMAL. AS A CREW, WE WERE SURPRISED BY THE LIGHT ACTIVITY ON THE BUSIEST TRAVEL DAY OF THE YR. AS WE APCHED THE DEP END OF RWY 35L, I, THE FO, ACKNOWLEDGED A 'CLRED AT THE APCH END OF RWY 35L, POS AND HOLD ON RWY 35L.' AS THE FO, I THEN CLRED THE ARR PATH TO THE R VISUALLY AND THEN LOOKED DOWN TO PUT AWAY MY ARPT DIAGRAM. AS I WAS PUTTING AWAY THE CHART, WE HEARD OUR COMPANY ACFT ENRTE TO IND CALL FOR WX OVER THE WRONG FREQ (TWR FREQ, WHICH WE WERE ON). WE WERE EMBARRASSED FOR THE COMPANY PLT TALKING ON THE WRONG FREQ. AS I LOOKED UP, THE CAPT ADVANCED THE THROTTLES, AND WE BEGAN THE TKOF ROLL. DURING THE TKOF, THE TWR ASKED THE CAPT TO CALL WHEN HE GOT TO HIS FINAL DEST. I ASKED HIM, 'WERE WE CLRED FOR TKOF?' WE HAD JUST MADE A TKOF WITHOUT CLRNC! LOOKING BACK, I WONDERED HOW WE COULD HAVE DONE THIS. MY CONCLUSIONS: I WAS TIRED FROM LACK OF SLEEP AND NOT AS ALERT AS I NORMALLY AM. THE COM BY OUR COMPANY OVER THE TWR FREQ TOOK US OUT OF OUR NORMAL FLOW. I DIDN'T QUESTION THE CAPT'S ADVANCING THE THROTTLES, EVEN THOUGH I HADN'T HEARD A TKOF CLRNC. I ASSUMED IF HE WAS ADVANCING THE THROTTLES, WE MUST HAVE BEEN CLRED.

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.