Narrative:

Takeoff from pit was on runway 10C behind a B757 and DC9 in that order. While climbing through approximately 2800 ft MSL, I received a TCASII TA immediately followed by an RA. For that phase of flight we were monitoring the 2.5 NM scale and flying the runway heading as assigned. The RA instructed me to 'descend, descend now' at a vertical speed of at least 200 FPM down. I was climbing at 1500-2000 FPM and immediately lowered the nose. The nose of the aircraft was no more than 5 degrees lower in pitch when the RA disappeared. In fact, the intruder disappeared completely from my mfd. The intruder had appeared at my 5 O'clock position and almost on top of me without warning. Neither myself nor my captain were able to confirm visual contact and reasoned that the B757 and DC9 were much too fast to be the culprit. After momentarily flying at a level pitch attitude and visually scanning the sky, we resumed our climb and turned on course to tri. I suspect the whole incident was due to a TCASII system malfunction or software glitch. Upon arrival at tri, I performed the TCASII self-test function. The system tested perfectly and still leaves me in doubt to a point about the validity of the RA given the spontaneous RA and lack of traffic in the area.

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Original NASA ASRS Text

Title: LTT CREW HAD TCASII RA IN PIT CLASS B AIRSPACE.

Narrative: TKOF FROM PIT WAS ON RWY 10C BEHIND A B757 AND DC9 IN THAT ORDER. WHILE CLBING THROUGH APPROX 2800 FT MSL, I RECEIVED A TCASII TA IMMEDIATELY FOLLOWED BY AN RA. FOR THAT PHASE OF FLT WE WERE MONITORING THE 2.5 NM SCALE AND FLYING THE RWY HDG AS ASSIGNED. THE RA INSTRUCTED ME TO 'DSND, DSND NOW' AT A VERT SPD OF AT LEAST 200 FPM DOWN. I WAS CLBING AT 1500-2000 FPM AND IMMEDIATELY LOWERED THE NOSE. THE NOSE OF THE ACFT WAS NO MORE THAN 5 DEGS LOWER IN PITCH WHEN THE RA DISAPPEARED. IN FACT, THE INTRUDER DISAPPEARED COMPLETELY FROM MY MFD. THE INTRUDER HAD APPEARED AT MY 5 O'CLOCK POS AND ALMOST ON TOP OF ME WITHOUT WARNING. NEITHER MYSELF NOR MY CAPT WERE ABLE TO CONFIRM VISUAL CONTACT AND REASONED THAT THE B757 AND DC9 WERE MUCH TOO FAST TO BE THE CULPRIT. AFTER MOMENTARILY FLYING AT A LEVEL PITCH ATTITUDE AND VISUALLY SCANNING THE SKY, WE RESUMED OUR CLB AND TURNED ON COURSE TO TRI. I SUSPECT THE WHOLE INCIDENT WAS DUE TO A TCASII SYS MALFUNCTION OR SOFTWARE GLITCH. UPON ARR AT TRI, I PERFORMED THE TCASII SELF-TEST FUNCTION. THE SYS TESTED PERFECTLY AND STILL LEAVES ME IN DOUBT TO A POINT ABOUT THE VALIDITY OF THE RA GIVEN THE SPONTANEOUS RA AND LACK OF TFC IN THE AREA.

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.