IFR cpr aircraft experienced TCASII RA at 8500 ft with military aircraft during descent into bfl.

Attributes
ACN	633485
Time
Date	200409
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bfl.airport
State Reference	CA
Altitude	msl single value : 8500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bfl.tracon
Operator	general aviation : corporate
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Operating Under FAR Part	Part 91
Flight Phase	descent : intermediate altitude
Route In Use	arrival : on vectors
Flight Plan	IFR
Aircraft 2
Operator	other
Make Model Name	Military
Operating Under FAR Part	Part 91
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 5100 flight time type : 3000
ASRS Report	633485
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Events
Anomaly	conflict : airborne critical
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance

Narrative:

While descending into bakersfield out of approximately 8500 ft on an IFR flight plan, the controller had us turn left to a heading of 120 degrees or approximately 30 degrees left for traffic. After completing the turn, we saw traffic pop up on our TCASII display at our 12 O'clock position and 400 ft below us. We received a traffic alert from our TCASII. Then we received an RA and command to 'descend' then 'climb.' I responded by descending at a higher rate, then tried to climb. Then the TCASII reported clear of conflict. We never saw the aircraft visually. We later found out this was a military aircraft. They said our closure rate was 900+ KTS. I was indicating 230 KTS. Maybe the controller saw a different picture on his radar scope, or at those speeds, if the military aircraft made a turn it didn't show on the controller's radar that quickly. With the information he had, he must have thought this was the right way for us to turn to stay clear.

Original NASA ASRS Text

Title: IFR CPR ACFT EXPERIENCED TCASII RA AT 8500 FT WITH MIL ACFT DURING DSCNT INTO BFL.

Narrative: WHILE DSNDING INTO BAKERSFIELD OUT OF APPROX 8500 FT ON AN IFR FLT PLAN, THE CTLR HAD US TURN L TO A HDG OF 120 DEGS OR APPROX 30 DEGS L FOR TFC. AFTER COMPLETING THE TURN, WE SAW TFC POP UP ON OUR TCASII DISPLAY AT OUR 12 O'CLOCK POS AND 400 FT BELOW US. WE RECEIVED A TFC ALERT FROM OUR TCASII. THEN WE RECEIVED AN RA AND COMMAND TO 'DSND' THEN 'CLB.' I RESPONDED BY DSNDING AT A HIGHER RATE, THEN TRIED TO CLB. THEN THE TCASII RPTED CLR OF CONFLICT. WE NEVER SAW THE ACFT VISUALLY. WE LATER FOUND OUT THIS WAS A MIL ACFT. THEY SAID OUR CLOSURE RATE WAS 900+ KTS. I WAS INDICATING 230 KTS. MAYBE THE CTLR SAW A DIFFERENT PICTURE ON HIS RADAR SCOPE, OR AT THOSE SPDS, IF THE MIL ACFT MADE A TURN IT DIDN'T SHOW ON THE CTLR'S RADAR THAT QUICKLY. WITH THE INFO HE HAD, HE MUST HAVE THOUGHT THIS WAS THE RIGHT WAY FOR US TO TURN TO STAY CLR.

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.