Narrative:

We were on radar vectors to final at newark international (ewr) and maintaining a heading of 350 degrees at 8000 ft MSL. The autoplt was engaged and altitude hold was on. Approach control issued a TA at our 12 O'clock position and 5 mi. It was a small single engine aircraft. I was the copilot and was not flying the aircraft. I advised approach control that I had negative contact on the aircraft but had a return on our TCASII. The TCASII showed an aircraft at that position and 600 ft above our altitude. A few moments later the TCASII issued a TA on the approaching aircraft and responded with an aural 'traffic' announcement. It was at that time that I observed a small aircraft slightly above and slightly to the right of our position. I advised approach control that I had the traffic in sight. A few seconds after I acquired visual contact with the aircraft, the TCASII announced a single command 'climb'. The captain immediately advanced the throttles, disconnected the autoplt and began a climb. I continued to maintain visual contact with the light aircraft until the TCASII announced 'monitor vertical speed'. At that moment I glanced down at my vertical speed indicator and saw that we were in a high rate of climb, but the vertical speed indicator 'fly to' arc was completely red, and was now commanding a descent. I reacquired visual contact with the other aircraft and saw that it was in a left hand bank turning away from us. Our altitude was now at 10000 ft MSL. A few seconds later the TCASII announced 'clear of conflict'. I reported to approach control that we had a TCASII TA and were returning to 8000 ft MSL.

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Original NASA ASRS Text

Title: TCASII RA CREATES AN ALTDEV ALT EXCURSION BY PIC.

Narrative: WE WERE ON RADAR VECTORS TO FINAL AT NEWARK INTL (EWR) AND MAINTAINING A HDG OF 350 DEGS AT 8000 FT MSL. THE AUTOPLT WAS ENGAGED AND ALT HOLD WAS ON. APCH CTL ISSUED A TA AT OUR 12 O'CLOCK POS AND 5 MI. IT WAS A SMALL SINGLE ENG ACFT. I WAS THE COPLT AND WAS NOT FLYING THE ACFT. I ADVISED APCH CTL THAT I HAD NEGATIVE CONTACT ON THE ACFT BUT HAD A RETURN ON OUR TCASII. THE TCASII SHOWED AN ACFT AT THAT POS AND 600 FT ABOVE OUR ALT. A FEW MOMENTS LATER THE TCASII ISSUED A TA ON THE APCHING ACFT AND RESPONDED WITH AN AURAL 'TFC' ANNOUNCEMENT. IT WAS AT THAT TIME THAT I OBSERVED A SMALL ACFT SLIGHTLY ABOVE AND SLIGHTLY TO THE R OF OUR POS. I ADVISED APCH CTL THAT I HAD THE TFC IN SIGHT. A FEW SECONDS AFTER I ACQUIRED VISUAL CONTACT WITH THE ACFT, THE TCASII ANNOUNCED A SINGLE COMMAND 'CLB'. THE CAPT IMMEDIATELY ADVANCED THE THROTTLES, DISCONNECTED THE AUTOPLT AND BEGAN A CLB. I CONTINUED TO MAINTAIN VISUAL CONTACT WITH THE LIGHT ACFT UNTIL THE TCASII ANNOUNCED 'MONITOR VERT SPD'. AT THAT MOMENT I GLANCED DOWN AT MY VERT SPD INDICATOR AND SAW THAT WE WERE IN A HIGH RATE OF CLB, BUT THE VERT SPD INDICATOR 'FLY TO' ARC WAS COMPLETELY RED, AND WAS NOW COMMANDING A DSCNT. I REACQUIRED VISUAL CONTACT WITH THE OTHER ACFT AND SAW THAT IT WAS IN A L HAND BANK TURNING AWAY FROM US. OUR ALT WAS NOW AT 10000 FT MSL. A FEW SECONDS LATER THE TCASII ANNOUNCED 'CLR OF CONFLICT'. I RPTED TO APCH CTL THAT WE HAD A TCASII TA AND WERE RETURNING TO 8000 FT MSL.

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.