Narrative:

This event happened in slc during takeoff on runway 34L. The flight was departing slc en route for twf. We taxied out to the active runway where an intersection takeoff clearance was issued. Runway 16R was the active runway at the time while runway 34L/right was in use for most of the day. This was our 5TH leg of the day and 3RD time to twf that day. No other aircraft was at the active runway or txwys on that side of the field and the closest aircraft was 10-15 mi away (not in sight until after takeoff). The clearance was given as 'cleared for takeoff at alpha 6 runway 16R. Turn right heading 280 degrees.' the first officer read back a garbled 'cleared for takeoff, turn left heading 280 degrees.' (a cargo aircraft incidentally was being cleared for takeoff on runway 34R, while runways 16R/left and 17 were in use.) miscom prevailed leading us to depart from the intersection on runway 34L (not 16R). We turned to 280 degrees immediately and realized our mistake. No other aircraft were within at least 6-10 mi and no action nor avoidance was taken nor necessary. The TCASII showed an aircraft 7-8 mi on base to runway 16R and we were not even close. We had the aircraft visually as well. We were not informed by ATC that we had erred and the flight continued event and incident free to twf. We landed on time at XX25 MST. We were then informed of the mishap the following morning by our chief pilot and FAA personnel upon arrival at slc. Both crew members (myself and first officer) were given line checks on the following flight to pih. Contributing factors that possibly led to this event: 1) miscom between pilots and controller. 2) a wrong readback by first officer and not acknowledged or addressed by captain or ATC controller. 3) a cargo aircraft was cleared for takeoff on runway 34R possibly leading to a subliminal understanding that the north runways were in use again. 4) multiple redundant takeoffs and lndgs from only slc and twf and the fact that runway 34R/left were in use for most of the day. 5) complacency on both pilots and the controller regarding readback and verification of runway assignment. 6) winds were calm and no other aircraft in the vicinity of the active runway and txwys. 7) intersection departure at runways mid-point with 2 high speeds from different runways (16R/34L) intersecting into the one intersection at A6 -- (angle of departure paths) from either direction.

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Original NASA ASRS Text

Title: FLC OF EMB120 MAKES AN INTXN TKOF IN THE WRONG DIRECTION. TFC USING RWYS IN BOTH DIRECTIONS AT THE TIME.

Narrative: THIS EVENT HAPPENED IN SLC DURING TKOF ON RWY 34L. THE FLT WAS DEPARTING SLC ENRTE FOR TWF. WE TAXIED OUT TO THE ACTIVE RWY WHERE AN INTXN TKOF CLRNC WAS ISSUED. RWY 16R WAS THE ACTIVE RWY AT THE TIME WHILE RWY 34L/R WAS IN USE FOR MOST OF THE DAY. THIS WAS OUR 5TH LEG OF THE DAY AND 3RD TIME TO TWF THAT DAY. NO OTHER ACFT WAS AT THE ACTIVE RWY OR TXWYS ON THAT SIDE OF THE FIELD AND THE CLOSEST ACFT WAS 10-15 MI AWAY (NOT IN SIGHT UNTIL AFTER TKOF). THE CLRNC WAS GIVEN AS 'CLRED FOR TKOF AT ALPHA 6 RWY 16R. TURN R HDG 280 DEGS.' THE FO READ BACK A GARBLED 'CLRED FOR TKOF, TURN L HDG 280 DEGS.' (A CARGO ACFT INCIDENTALLY WAS BEING CLRED FOR TKOF ON RWY 34R, WHILE RWYS 16R/L AND 17 WERE IN USE.) MISCOM PREVAILED LEADING US TO DEPART FROM THE INTXN ON RWY 34L (NOT 16R). WE TURNED TO 280 DEGS IMMEDIATELY AND REALIZED OUR MISTAKE. NO OTHER ACFT WERE WITHIN AT LEAST 6-10 MI AND NO ACTION NOR AVOIDANCE WAS TAKEN NOR NECESSARY. THE TCASII SHOWED AN ACFT 7-8 MI ON BASE TO RWY 16R AND WE WERE NOT EVEN CLOSE. WE HAD THE ACFT VISUALLY AS WELL. WE WERE NOT INFORMED BY ATC THAT WE HAD ERRED AND THE FLT CONTINUED EVENT AND INCIDENT FREE TO TWF. WE LANDED ON TIME AT XX25 MST. WE WERE THEN INFORMED OF THE MISHAP THE FOLLOWING MORNING BY OUR CHIEF PLT AND FAA PERSONNEL UPON ARR AT SLC. BOTH CREW MEMBERS (MYSELF AND FO) WERE GIVEN LINE CHKS ON THE FOLLOWING FLT TO PIH. CONTRIBUTING FACTORS THAT POSSIBLY LED TO THIS EVENT: 1) MISCOM BTWN PLTS AND CTLR. 2) A WRONG READBACK BY FO AND NOT ACKNOWLEDGED OR ADDRESSED BY CAPT OR ATC CTLR. 3) A CARGO ACFT WAS CLRED FOR TKOF ON RWY 34R POSSIBLY LEADING TO A SUBLIMINAL UNDERSTANDING THAT THE N RWYS WERE IN USE AGAIN. 4) MULTIPLE REDUNDANT TKOFS AND LNDGS FROM ONLY SLC AND TWF AND THE FACT THAT RWY 34R/L WERE IN USE FOR MOST OF THE DAY. 5) COMPLACENCY ON BOTH PLTS AND THE CTLR REGARDING READBACK AND VERIFICATION OF RWY ASSIGNMENT. 6) WINDS WERE CALM AND NO OTHER ACFT IN THE VICINITY OF THE ACTIVE RWY AND TXWYS. 7) INTXN DEP AT RWYS MID-POINT WITH 2 HIGH SPDS FROM DIFFERENT RWYS (16R/34L) INTERSECTING INTO THE ONE INTXN AT A6 -- (ANGLE OF DEP PATHS) FROM EITHER DIRECTION.

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.