Air carrier at cruise has TCASII RA. Climbs.

Attributes
ACN	252547
Time
Date	199309
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : bdf
State Reference	IN
Altitude	msl bound lower : 28000 msl bound upper : 29000
Aircraft 1
Controlling Facilities	artcc : zau
Operator	common carrier : air carrier
Make Model Name	Large Transport
Flight Phase	cruise other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : cfi pilot : atp pilot : commercial pilot : flight engineer pilot : instrument
Experience	flight time last 90 days : 200 flight time total : 5000 flight time type : 1000
ASRS Report	252547
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 500 vertical : 1000
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	other

Narrative:

At cruise, we received a TCASII RA to climb due to traffic. The TCASII screen indicated an approaching opposite direction target climbing through FL270 (we were at FL280). We initiated a climb to comply with the TCASII directions and leveled at FL290. At that time the TCASII warning subsided. We notified ATC (ZAU 134.02) and began a descent back to our assigned altitude of FL280. Lesson learned: always be vigilant! It may save your life.

Original NASA ASRS Text

Title: ACR AT CRUISE HAS TCASII RA. CLBS.

Narrative: AT CRUISE, WE RECEIVED A TCASII RA TO CLB DUE TO TFC. THE TCASII SCREEN INDICATED AN APCHING OPPOSITE DIRECTION TARGET CLBING THROUGH FL270 (WE WERE AT FL280). WE INITIATED A CLB TO COMPLY WITH THE TCASII DIRECTIONS AND LEVELED AT FL290. AT THAT TIME THE TCASII WARNING SUBSIDED. WE NOTIFIED ATC (ZAU 134.02) AND BEGAN A DSCNT BACK TO OUR ASSIGNED ALT OF FL280. LESSON LEARNED: ALWAYS BE VIGILANT! IT MAY SAVE YOUR LIFE.

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.