An air carrier B-737 used its TCASII to avoid a dhc-8.

Attributes
ACN	266720
Time
Date	199403
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : den
State Reference	CO
Altitude	msl bound lower : 13600 msl bound upper : 13600
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : edw
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	enroute airway : zdv
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Dash 8 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 135
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Experience	flight time last 90 days : 200 flight time total : 6000
ASRS Report	266720
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : took evasive action other
Consequence	Other
Miss Distance	horizontal : 6000 vertical : 200
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

Received and complied with TCASII RA 'descend' command while navigating northeast direct to den VOR and descending through 13600 ft for assigned altitude 11000 ft. Dash 8 in shallow left turn and climb passed to our right about 1 mi and opposite direction and slightly above our altitude. TCASII target indicated 13100 ft when first TA sounded. Den approach made first call to us, apparently with intent of issuing TA, sometime after our initial TCASII TA. Normal maneuvers were sufficient.

Original NASA ASRS Text

Title: AN ACR B-737 USED ITS TCASII TO AVOID A DHC-8.

Narrative: RECEIVED AND COMPLIED WITH TCASII RA 'DSND' COMMAND WHILE NAVING NE DIRECT TO DEN VOR AND DSNDING THROUGH 13600 FT FOR ASSIGNED ALT 11000 FT. DASH 8 IN SHALLOW L TURN AND CLB PASSED TO OUR R ABOUT 1 MI AND OPPOSITE DIRECTION AND SLIGHTLY ABOVE OUR ALT. TCASII TARGET INDICATED 13100 FT WHEN FIRST TA SOUNDED. DEN APCH MADE FIRST CALL TO US, APPARENTLY WITH INTENT OF ISSUING TA, SOMETIME AFTER OUR INITIAL TCASII TA. NORMAL MANEUVERS WERE SUFFICIENT.

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.