Narrative:

While in level cruise at FL270, our TCASII picked up traffic at 12 'clock and approximately 20 NM and climbing. When the traffic was approximately 15 NM away, TCASII issued a TA followed shortly by an RA commanding a climb to elude traffic. RA command was followed with a level off at 27800 ft. Our aircraft was returned to FL270 after cle center was advised of our RA and climb. ATC then advised us that the traffic climbing toward us was to level off at FL260. The opposing traffic also received a TCASII RA command to level off. Our RA was received while the intruder traffic was still 1900 ft below us. It appears that the TCASII system worked as advertised, but we followed a mandatory climb alert that caused us to be almost a thousand ft above our assigned altitude. Fortunately we did not come in conflict with traffic above us, however, I have to be very concerned about a similar situation occurring again, especially in a crowded traffic area around a busy airport.

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Original NASA ASRS Text

Title: MLG AT CRUISE HAS TCASII TFC SHOW AT 12 O'CLOCK. RECEIVES TA, THEN RA TO CLB. COMPLIES.

Narrative: WHILE IN LEVEL CRUISE AT FL270, OUR TCASII PICKED UP TFC AT 12 'CLOCK AND APPROX 20 NM AND CLBING. WHEN THE TFC WAS APPROX 15 NM AWAY, TCASII ISSUED A TA FOLLOWED SHORTLY BY AN RA COMMANDING A CLB TO ELUDE TFC. RA COMMAND WAS FOLLOWED WITH A LEVEL OFF AT 27800 FT. OUR ACFT WAS RETURNED TO FL270 AFTER CLE CTR WAS ADVISED OF OUR RA AND CLB. ATC THEN ADVISED US THAT THE TFC CLBING TOWARD US WAS TO LEVEL OFF AT FL260. THE OPPOSING TFC ALSO RECEIVED A TCASII RA COMMAND TO LEVEL OFF. OUR RA WAS RECEIVED WHILE THE INTRUDER TFC WAS STILL 1900 FT BELOW US. IT APPEARS THAT THE TCASII SYS WORKED AS ADVERTISED, BUT WE FOLLOWED A MANDATORY CLB ALERT THAT CAUSED US TO BE ALMOST A THOUSAND FT ABOVE OUR ASSIGNED ALT. FORTUNATELY WE DID NOT COME IN CONFLICT WITH TFC ABOVE US, HOWEVER, I HAVE TO BE VERY CONCERNED ABOUT A SIMILAR SITUATION OCCURRING AGAIN, ESPECIALLY IN A CROWDED TFC AREA AROUND A BUSY ARPT.

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.