TCASII RA descent to avoid conflict with descending aircraft.

Attributes
ACN	185142
Time
Date	199107
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : gbn
State Reference	NM
Altitude	msl bound lower : 27200 msl bound upper : 28000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zab
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Flight Plan	IFR
Aircraft 2
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 : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 10000 flight time type : 500
ASRS Report	185142
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	conflict : airborne less severe
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 1000 vertical : 2000
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

In cruise at FL280 TCAS issued a traffic advisory for an aircraft at 12 O'clock and 10 mi. Traffic was 2000 ft above us and descending. At 5 mi separation and traffic 1500 ft above and descending, TCAS issued a resolution advisory to descend. Descended 800 ft and traffic passed by to our left. Was unable to make radio contact with ATC during this due to congestion on frequency. After climbing back to FL280 ATC was advised of our actions.

Original NASA ASRS Text

Title: TCASII RA DSCNT TO AVOID CONFLICT WITH DSNDING ACFT.

Narrative: IN CRUISE AT FL280 TCAS ISSUED A TFC ADVISORY FOR AN ACFT AT 12 O'CLOCK AND 10 MI. TFC WAS 2000 FT ABOVE US AND DSNDING. AT 5 MI SEPARATION AND TFC 1500 FT ABOVE AND DSNDING, TCAS ISSUED A RESOLUTION ADVISORY TO DSND. DSNDED 800 FT AND TFC PASSED BY TO OUR L. WAS UNABLE TO MAKE RADIO CONTACT WITH ATC DURING THIS DUE TO CONGESTION ON FREQ. AFTER CLBING BACK TO FL280 ATC WAS ADVISED OF OUR ACTIONS.

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.