Medium large transport has TCASII RA while at cruise.

Attributes
ACN	248033
Time
Date	199308
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : oma
State Reference	NE
Altitude	msl bound lower : 27300 msl bound upper : 28000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zmp tower : mia
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
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	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 4500 flight time type : 500
ASRS Report	248033
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude other anomaly other other spatial deviation
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 1000 vertical : 1700
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While cruising at FL280 in a clearance direct to the omaha VOR, a 'descend' RA was given by our TCASII. No TA was given. I disconnected the autoplt, started a descent, looked at the TCASII, saw a target at 11 O'clock at about 6 mi. I cleared my flight path and offset him to the left by turning right in my descent. The captain saw him above us to the left. We told ATC we were descending for an RA. We bottomed out at 27300 ft MSL and climbed back to FL280. ATC said it was air carrier flight, eastbound at FL290. I do not recall whether or not our TCASII showed him to be level or above us at the outset of the RA, due to my clearing of my flight path and monitoring of the vertical speed to comply with the RA.

Original NASA ASRS Text

Title: MLG HAS TCASII RA WHILE AT CRUISE.

Narrative: WHILE CRUISING AT FL280 IN A CLRNC DIRECT TO THE OMAHA VOR, A 'DSND' RA WAS GIVEN BY OUR TCASII. NO TA WAS GIVEN. I DISCONNECTED THE AUTOPLT, STARTED A DSCNT, LOOKED AT THE TCASII, SAW A TARGET AT 11 O'CLOCK AT ABOUT 6 MI. I CLRED MY FLT PATH AND OFFSET HIM TO THE L BY TURNING R IN MY DSCNT. THE CAPT SAW HIM ABOVE US TO THE L. WE TOLD ATC WE WERE DSNDING FOR AN RA. WE BOTTOMED OUT AT 27300 FT MSL AND CLBED BACK TO FL280. ATC SAID IT WAS ACR FLT, EBOUND AT FL290. I DO NOT RECALL WHETHER OR NOT OUR TCASII SHOWED HIM TO BE LEVEL OR ABOVE US AT THE OUTSET OF THE RA, DUE TO MY CLRING OF MY FLT PATH AND MONITORING OF THE VERT SPD TO COMPLY WITH THE RA.

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.