CL60 TCASII event with unknown aircraft.

Attributes
ACN	569670
Time
Date	200212
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : bwg.vortac
State Reference	TN
Altitude	msl bound lower : 25000 msl bound upper : 26000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zme.artcc
Operator	common carrier : air carrier
Make Model Name	Challenger CL600
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zme.artcc
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	observation : company check pilot
Qualification	pilot : multi engine pilot : cfi pilot : atp
Experience	flight time last 90 days : 60 flight time total : 6500 flight time type : 900
ASRS Report	569670
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne critical
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	flight crew : returned to assigned altitude
Miss Distance	vertical : 1500
Supplementary
Problem Areas	Aircraft ATC Human Performance
Primary Problem	Aircraft

Narrative:

While in cruise at FL250, approximately 25 NM south of bwg VOR, the TCASII issued an RA with instructions 'climb climb.' the target was approximately 1500 ft below us and climbing. We did not have a visual contact. There were no instructions or advisories from ZME on 124.27. We followed the RA instructions and immediately notified ATC. We climbed to FL260 before TCASII announced 'clear of conflict.' we returned to assigned altitude of FL250 without further incident.

Original NASA ASRS Text

Title: CL60 TCASII EVENT WITH UNKNOWN ACFT.

Narrative: WHILE IN CRUISE AT FL250, APPROX 25 NM S OF BWG VOR, THE TCASII ISSUED AN RA WITH INSTRUCTIONS 'CLB CLB.' THE TARGET WAS APPROX 1500 FT BELOW US AND CLIMBING. WE DID NOT HAVE A VISUAL CONTACT. THERE WERE NO INSTRUCTIONS OR ADVISORIES FROM ZME ON 124.27. WE FOLLOWED THE RA INSTRUCTIONS AND IMMEDIATELY NOTIFIED ATC. WE CLBED TO FL260 BEFORE TCASII ANNOUNCED 'CLR OF CONFLICT.' WE RETURNED TO ASSIGNED ALT OF FL250 WITHOUT FURTHER INCIDENT.

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.