<< >> NASA ASRS Report 379958, September 1997

Mdt flight crew has TCASII traffic indicated while descending on IFR flight plan. ATC tells them to maintain altitude then descends another aircraft to same altitude. No visual contact and TCASII gives an RA. Operational error.

Attributes
ACN	379958
Time
Date	199709
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : cvg
State Reference	OH
Altitude	msl bound lower : 9000 msl bound upper : 9800
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : cvg tower : ind
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	descent other
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	other : unknown
Flight Phase	descent other
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 13000 flight time type : 1500
ASRS Report	379958
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation other anomaly other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 6000 vertical : 800
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

On descent passing 10000 ft for 9000 ft, TCASII indicated traffic above us. Cvg approach control, when questioned about traffic, told us to maintain 9000 ft and turn to 270 degrees and keep visual on traffic. Approach control then descended traffic to 9000 ft on top of us. We never accepted visual on overhead traffic and told them not to descend traffic because of not being able to keep visual separation. While in turn to 270 degrees we received TCASII RA requiring evasive action. It indicated only 800 ft separation and closing. This action resulted in an airspeed of 260 KTS at about 9800 ft while evasive action was taken. Flight continued to airport without further problem.

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Original NASA ASRS Text

Title: MDT FLC HAS TCASII TFC INDICATED WHILE DSNDING ON IFR FLT PLAN. ATC TELLS THEM TO MAINTAIN ALT THEN DSNDS ANOTHER ACFT TO SAME ALT. NO VISUAL CONTACT AND TCASII GIVES AN RA. OPERROR.

Narrative: ON DSCNT PASSING 10000 FT FOR 9000 FT, TCASII INDICATED TFC ABOVE US. CVG APCH CTL, WHEN QUESTIONED ABOUT TFC, TOLD US TO MAINTAIN 9000 FT AND TURN TO 270 DEGS AND KEEP VISUAL ON TFC. APCH CTL THEN DSNDED TFC TO 9000 FT ON TOP OF US. WE NEVER ACCEPTED VISUAL ON OVERHEAD TFC AND TOLD THEM NOT TO DSND TFC BECAUSE OF NOT BEING ABLE TO KEEP VISUAL SEPARATION. WHILE IN TURN TO 270 DEGS WE RECEIVED TCASII RA REQUIRING EVASIVE ACTION. IT INDICATED ONLY 800 FT SEPARATION AND CLOSING. THIS ACTION RESULTED IN AN AIRSPD OF 260 KTS AT ABOUT 9800 FT WHILE EVASIVE ACTION WAS TAKEN. FLT CONTINUED TO ARPT WITHOUT FURTHER PROB.

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.