Narrative:

Location: bgi 090 degree radial, 1 DME. While position and hold runway 9, amended clearance vector heading 345 degrees given. After takeoff, turned left to 345 degree heading at 400 ft per clearance. Captain kept flaps at 15 degrees to expedite turn. While in turn, we realized the light twin piston commander would be ahead of us, with a surprisingly high rate of climb. The captain realized the conflict potential and continued his turn further west to a heading of 270 degrees to maintain separation because a turn to the east would have diminished the existing separation. It was then we both realized the 345 degree heading after takeoff was not intended to supersede the noise abatement procedure requiring a climb to 2500 ft or crossing 7 DME before turning to a north heading. We failed to follow the noise abatement procedure, in error, believing the tower clearance superseded the published procedure. More importantly, we failed to use common sense. We should have queried the tower's issuance of a heading after takeoff that would put us directly behind a slower piston. Captain and I errantly assumed we could outclb the light twin. In addition to our failure to use common sense, we were mislead by the united states procedure whereby an amended heading after takeoff may sometimes supersede the published procedure. Supplemental information from acn 496158: it was then that we both realized the departure heading was not intended to supersede the noise abatement restr on turns below 2500 ft or 7 DME. Attaining either one was the appropriate time to turn to 345 degrees. At this point, it was too late to turn back. I continued to turn to 270 degrees to stay away from the other aircraft while we maintained visual contact. We crossed his altitude showing just over 2 mi separation on TCASII -- again, in visual contact.

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Original NASA ASRS Text

Title: A B757-200 PIC EXPERIENCES A POTENTIAL CONFLICT WITH DEP TFC AS HE TURNS TOO EARLY BECAUSE OF MISINTERP OF AMENDED DEP CLRNC AT TBPB, FO.

Narrative: LOCATION: BGI 090 DEG RADIAL, 1 DME. WHILE POS AND HOLD RWY 9, AMENDED CLRNC VECTOR HDG 345 DEGS GIVEN. AFTER TKOF, TURNED L TO 345 DEG HDG AT 400 FT PER CLRNC. CAPT KEPT FLAPS AT 15 DEGS TO EXPEDITE TURN. WHILE IN TURN, WE REALIZED THE LIGHT TWIN PISTON COMMANDER WOULD BE AHEAD OF US, WITH A SURPRISINGLY HIGH RATE OF CLB. THE CAPT REALIZED THE CONFLICT POTENTIAL AND CONTINUED HIS TURN FURTHER W TO A HDG OF 270 DEGS TO MAINTAIN SEPARATION BECAUSE A TURN TO THE E WOULD HAVE DIMINISHED THE EXISTING SEPARATION. IT WAS THEN WE BOTH REALIZED THE 345 DEG HDG AFTER TKOF WAS NOT INTENDED TO SUPERSEDE THE NOISE ABATEMENT PROC REQUIRING A CLB TO 2500 FT OR XING 7 DME BEFORE TURNING TO A N HDG. WE FAILED TO FOLLOW THE NOISE ABATEMENT PROC, IN ERROR, BELIEVING THE TWR CLRNC SUPERSEDED THE PUBLISHED PROC. MORE IMPORTANTLY, WE FAILED TO USE COMMON SENSE. WE SHOULD HAVE QUERIED THE TWR'S ISSUANCE OF A HDG AFTER TKOF THAT WOULD PUT US DIRECTLY BEHIND A SLOWER PISTON. CAPT AND I ERRANTLY ASSUMED WE COULD OUTCLB THE LIGHT TWIN. IN ADDITION TO OUR FAILURE TO USE COMMON SENSE, WE WERE MISLEAD BY THE UNITED STATES PROC WHEREBY AN AMENDED HDG AFTER TKOF MAY SOMETIMES SUPERSEDE THE PUBLISHED PROC. SUPPLEMENTAL INFO FROM ACN 496158: IT WAS THEN THAT WE BOTH REALIZED THE DEP HDG WAS NOT INTENDED TO SUPERSEDE THE NOISE ABATEMENT RESTR ON TURNS BELOW 2500 FT OR 7 DME. ATTAINING EITHER ONE WAS THE APPROPRIATE TIME TO TURN TO 345 DEGS. AT THIS POINT, IT WAS TOO LATE TO TURN BACK. I CONTINUED TO TURN TO 270 DEGS TO STAY AWAY FROM THE OTHER ACFT WHILE WE MAINTAINED VISUAL CONTACT. WE CROSSED HIS ALT SHOWING JUST OVER 2 MI SEPARATION ON TCASII -- AGAIN, IN VISUAL CONTACT.

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.