Narrative:

I received an initial clearance to 5000 ft MSL. The clearance was amended to 4000 ft. I was instructed that after 4000 ft, turn to a 250 degree heading. For a brief moment, I believed that after 4000 ft and climbing to 5000 ft, turn to 250 degrees. Quickly realizing I was not cleared to 5000 ft but rather maintain 4000 ft, I maneuvered to maintain 4000 ft. At the time of correction, I was through 4000 ft and correcting back to 4000 ft. I believe the event occurred because another aircraft was being sequenced for the approach while I was on the departure. Both the approach and this particular departure use the exact same airspace. Subsequently, because of additional traffic in the airspace, I needed to be vectored off of the SID for traffic avoidance. At all times I had the traffic in sight and was maintaining visual separation. I believe the mistake occurred because of communication breakdown between pilot and controller. The phrase 'maintain' instead of 'after' would have added clarity to the situation. Additionally, if there was going to be a potential traffic conflict, then my aircraft should have been held on the ground awaiting release. This event could be prevented in the future by possibly giving greater spacing between departing jet traffic and slower GA aircraft. If traffic is going to be a factor on a turbine aircraft SID departure requiring radical vector off the SID to maintain traffic separation, then possibly the turbine aircraft should be held on the ground or the other traffic should be well clear of the SID.

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Original NASA ASRS Text

Title: PLT MOMENTARILY CLBED THROUGH CLRED ALT. BELIEVES CTLR PHRASEOLOGY WAS MISLEADING.

Narrative: I RECEIVED AN INITIAL CLRNC TO 5000 FT MSL. THE CLRNC WAS AMENDED TO 4000 FT. I WAS INSTRUCTED THAT AFTER 4000 FT, TURN TO A 250 DEG HDG. FOR A BRIEF MOMENT, I BELIEVED THAT AFTER 4000 FT AND CLBING TO 5000 FT, TURN TO 250 DEGS. QUICKLY REALIZING I WAS NOT CLRED TO 5000 FT BUT RATHER MAINTAIN 4000 FT, I MANEUVERED TO MAINTAIN 4000 FT. AT THE TIME OF CORRECTION, I WAS THROUGH 4000 FT AND CORRECTING BACK TO 4000 FT. I BELIEVE THE EVENT OCCURRED BECAUSE ANOTHER ACFT WAS BEING SEQUENCED FOR THE APCH WHILE I WAS ON THE DEP. BOTH THE APCH AND THIS PARTICULAR DEP USE THE EXACT SAME AIRSPACE. SUBSEQUENTLY, BECAUSE OF ADDITIONAL TFC IN THE AIRSPACE, I NEEDED TO BE VECTORED OFF OF THE SID FOR TFC AVOIDANCE. AT ALL TIMES I HAD THE TFC IN SIGHT AND WAS MAINTAINING VISUAL SEPARATION. I BELIEVE THE MISTAKE OCCURRED BECAUSE OF COM BREAKDOWN BTWN PLT AND CTLR. THE PHRASE 'MAINTAIN' INSTEAD OF 'AFTER' WOULD HAVE ADDED CLARITY TO THE SIT. ADDITIONALLY, IF THERE WAS GOING TO BE A POTENTIAL TFC CONFLICT, THEN MY ACFT SHOULD HAVE BEEN HELD ON THE GND AWAITING RELEASE. THIS EVENT COULD BE PREVENTED IN THE FUTURE BY POSSIBLY GIVING GREATER SPACING BTWN DEPARTING JET TFC AND SLOWER GA ACFT. IF TFC IS GOING TO BE A FACTOR ON A TURBINE ACFT SID DEP REQUIRING RADICAL VECTOR OFF THE SID TO MAINTAIN TFC SEPARATION, THEN POSSIBLY THE TURBINE ACFT SHOULD BE HELD ON THE GND OR THE OTHER TFC SHOULD BE WELL CLR OF THE SID.

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.