Narrative:

I was dispatched as PIC of a CL60. At our departure time of around XA30, the sky was clear and visibility was nearly unrestr. During my departure briefing, I briefed my copilot of my intention to depart VFR and pick our instrument clearance up once airborne. Our takeoff went well. After gear and flap retraction, I reduced power and leveled at approximately 2500 ft MSL (spa field elevation is 801 ft MSL), while my copilot finished the after takeoff and began the climb checklists. Departing the pattern to the northwest, we noticed traffic on the TCASII display, 2 aircraft ahead both less than 2000 ft above us. As one aircraft showed slightly right of our course 700 ft above, and the other was about 1900 ft above us to the left (both nearing our aircraft on apparently constant bearings on the TCASII display), I elected to descend approximately 200-300 ft to place 1000 vertical separation between our aircraft and the closer target until we got it in sight visually. Just as I was about to begin the descent, we got a momentary TA from TCASII. We descended to approximately 2200 ft MSL and continued searching visually for both targets. Still thinking of the elevation at the spa airport (which is 801 ft), I estimated our altitude above the ground was still over 1400 ft AGL. Due to the subtly rising uneven terrain northwest of the airport, our visually maintaining altitude resulted in the aircraft's apparently touching 1000 ft AGL ('1000' was reported by the voice advisory system). Upon hearing the audio callout, my copilot restated '1000 ft, climb.' I initiated a near maximum performance climb.

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Original NASA ASRS Text

Title: WHILE OCCUPIED WITH LOCATING VISUALLY 2 ACFT DISPLAYING ON TCASII, FLC OF LTT ACFT COMES WITHIN 1000 FT AGL AND GETS GPWS WARNING.

Narrative: I WAS DISPATCHED AS PIC OF A CL60. AT OUR DEP TIME OF AROUND XA30, THE SKY WAS CLR AND VISIBILITY WAS NEARLY UNRESTR. DURING MY DEP BRIEFING, I BRIEFED MY COPLT OF MY INTENTION TO DEPART VFR AND PICK OUR INST CLRNC UP ONCE AIRBORNE. OUR TKOF WENT WELL. AFTER GEAR AND FLAP RETRACTION, I REDUCED PWR AND LEVELED AT APPROX 2500 FT MSL (SPA FIELD ELEVATION IS 801 FT MSL), WHILE MY COPLT FINISHED THE AFTER TKOF AND BEGAN THE CLB CHKLISTS. DEPARTING THE PATTERN TO THE NW, WE NOTICED TFC ON THE TCASII DISPLAY, 2 ACFT AHEAD BOTH LESS THAN 2000 FT ABOVE US. AS ONE ACFT SHOWED SLIGHTLY R OF OUR COURSE 700 FT ABOVE, AND THE OTHER WAS ABOUT 1900 FT ABOVE US TO THE L (BOTH NEARING OUR ACFT ON APPARENTLY CONSTANT BEARINGS ON THE TCASII DISPLAY), I ELECTED TO DSND APPROX 200-300 FT TO PLACE 1000 VERT SEPARATION BTWN OUR ACFT AND THE CLOSER TARGET UNTIL WE GOT IT IN SIGHT VISUALLY. JUST AS I WAS ABOUT TO BEGIN THE DSCNT, WE GOT A MOMENTARY TA FROM TCASII. WE DSNDED TO APPROX 2200 FT MSL AND CONTINUED SEARCHING VISUALLY FOR BOTH TARGETS. STILL THINKING OF THE ELEVATION AT THE SPA ARPT (WHICH IS 801 FT), I ESTIMATED OUR ALT ABOVE THE GND WAS STILL OVER 1400 FT AGL. DUE TO THE SUBTLY RISING UNEVEN TERRAIN NW OF THE ARPT, OUR VISUALLY MAINTAINING ALT RESULTED IN THE ACFT'S APPARENTLY TOUCHING 1000 FT AGL ('1000' WAS RPTED BY THE VOICE ADVISORY SYS). UPON HEARING THE AUDIO CALLOUT, MY COPLT RESTATED '1000 FT, CLB.' I INITIATED A NEAR MAX PERFORMANCE CLB.

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.