Narrative:

It was the last leg of the 5 we were scheduled. After taxi checks were completed and ramp control handed us off to ground control, we received clearance to taxi to runway 16R. Somewhere along taxiway east, the captain asked if we were light enough for an intersection takeoff, and requested that I ask for it from ground. I immediately looked up our takeoff weight for an A6 intersection departure, confirmed we were light enough, and then contacted tower for clearance. As I waited for ATC clearance, I began the before takeoff checklist requiring notification of the flight attendant, flap setting and other verbal and physical checks. During my challenge and response from the captain, ATC cleared us for 'takeoff, A6 intersection departure,' and what I perceived as 'left turn 280 degrees.' I read back the clearance, but stuttered, unsure of the 'turnout' direction. The captain then entered the runway, heading north and applied power for takeoff, called 'set power' and as I struggled to clear my mind of the clearance we received, I adjusted my thinking to the takeoff roll, callouts, and watching for traffic. Takeoff was normal. After about 400 ft, tower requested 'immediate' turn 280 degrees. We noted an aircraft about our 1-2 O'clock position, and approximately 6-10 mi on our TCASII. We then began to realize our error in taking off the wrong direction. No other incidents. Possible causes: 1) dark cockpit, unable to view ATIS information. 2) confusion with ATC clearance. 3) being in too big of a hurry. 4) breakdown of crew communication/coordination during a critical phase of flight. 5) failure to maintain situational awareness. Complacency! 6) failure of ATC to verify readback or clarify it.

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Original NASA ASRS Text

Title: FLC OF AN EMBRAER BRASILIA EMB120 (E120) TOOK OFF IN THE OPPOSITE DIRECTION DURING AN INTXN TKOF. IT WAS AT NIGHTTIME, AND THE CAPT BECAME DISORIENTED WHEN TAXIING INTO POS FOR TKOF.

Narrative: IT WAS THE LAST LEG OF THE 5 WE WERE SCHEDULED. AFTER TAXI CHKS WERE COMPLETED AND RAMP CTL HANDED US OFF TO GND CTL, WE RECEIVED CLRNC TO TAXI TO RWY 16R. SOMEWHERE ALONG TXWY E, THE CAPT ASKED IF WE WERE LIGHT ENOUGH FOR AN INTXN TKOF, AND REQUESTED THAT I ASK FOR IT FROM GND. I IMMEDIATELY LOOKED UP OUR TKOF WT FOR AN A6 INTXN DEP, CONFIRMED WE WERE LIGHT ENOUGH, AND THEN CONTACTED TWR FOR CLRNC. AS I WAITED FOR ATC CLRNC, I BEGAN THE BEFORE TKOF CHKLIST REQUIRING NOTIFICATION OF THE FLT ATTENDANT, FLAP SETTING AND OTHER VERBAL AND PHYSICAL CHKS. DURING MY CHALLENGE AND RESPONSE FROM THE CAPT, ATC CLRED US FOR 'TKOF, A6 INTXN DEP,' AND WHAT I PERCEIVED AS 'L TURN 280 DEGS.' I READ BACK THE CLRNC, BUT STUTTERED, UNSURE OF THE 'TURNOUT' DIRECTION. THE CAPT THEN ENTERED THE RWY, HDG N AND APPLIED PWR FOR TKOF, CALLED 'SET PWR' AND AS I STRUGGLED TO CLR MY MIND OF THE CLRNC WE RECEIVED, I ADJUSTED MY THINKING TO THE TKOF ROLL, CALLOUTS, AND WATCHING FOR TFC. TKOF WAS NORMAL. AFTER ABOUT 400 FT, TWR REQUESTED 'IMMEDIATE' TURN 280 DEGS. WE NOTED AN ACFT ABOUT OUR 1-2 O'CLOCK POS, AND APPROX 6-10 MI ON OUR TCASII. WE THEN BEGAN TO REALIZE OUR ERROR IN TAKING OFF THE WRONG DIRECTION. NO OTHER INCIDENTS. POSSIBLE CAUSES: 1) DARK COCKPIT, UNABLE TO VIEW ATIS INFO. 2) CONFUSION WITH ATC CLRNC. 3) BEING IN TOO BIG OF A HURRY. 4) BREAKDOWN OF CREW COM/COORD DURING A CRITICAL PHASE OF FLT. 5) FAILURE TO MAINTAIN SITUATIONAL AWARENESS. COMPLACENCY! 6) FAILURE OF ATC TO VERIFY READBACK OR CLARIFY IT.

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.