TCASII warning causes medium large transport to climb from a conflict.

Attributes
ACN	251945
Time
Date	199309
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : pns
State Reference	FL
Altitude	msl bound lower : 9000 msl bound upper : 10000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : pns
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Aircraft 2
Operator	other
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Plan	None
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 210 flight time total : 10500 flight time type : 3800
ASRS Report	251945
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : nmac
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	vertical : 200
Supplementary
Primary Problem	Flight Crew Human Performance

Narrative:

During descent to pensacola, we were cleared all the way to 3000 ft, then approach mentioned there was traffic and we were told to stop our descent at 9000 ft. While leveled at this altitude, we heard a TCASII TA followed by a 'climb, do not descend' command. A blip suddenly appeared on the screen showing 200 ft below our altitude. The captain, who was flying the aircraft, immediately climbed to 10000 ft and reported this to ATC. Upon landing the captain contacted ATC and was told over the telephone that a few seconds before this occurred, a military plane was in the area and had cancelled its flight plan, and proceeded VFR. They also concurred that the altitude of this unknown aircraft was 8800 ft.

Original NASA ASRS Text

Title: TCASII WARNING CAUSES MLG TO CLB FROM A CONFLICT.

Narrative: DURING DSCNT TO PENSACOLA, WE WERE CLRED ALL THE WAY TO 3000 FT, THEN APCH MENTIONED THERE WAS TFC AND WE WERE TOLD TO STOP OUR DSCNT AT 9000 FT. WHILE LEVELED AT THIS ALT, WE HEARD A TCASII TA FOLLOWED BY A 'CLB, DO NOT DSND' COMMAND. A BLIP SUDDENLY APPEARED ON THE SCREEN SHOWING 200 FT BELOW OUR ALT. THE CAPT, WHO WAS FLYING THE ACFT, IMMEDIATELY CLBED TO 10000 FT AND RPTED THIS TO ATC. UPON LNDG THE CAPT CONTACTED ATC AND WAS TOLD OVER THE TELEPHONE THAT A FEW SECONDS BEFORE THIS OCCURRED, A MIL PLANE WAS IN THE AREA AND HAD CANCELLED ITS FLT PLAN, AND PROCEEDED VFR. THEY ALSO CONCURRED THAT THE ALT OF THIS UNKNOWN ACFT WAS 8800 FT.

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.