<< >> NASA ASRS Report 270875, March 1994

TCASII logic caused air carrier X to respond to TCASII RA when standard separation existed from air carrier Y.

Attributes
ACN	270875
Time
Date	199403
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : bdf
State Reference	IL
Altitude	msl bound lower : 28000 msl bound upper : 29000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau artcc : zoa
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	270875
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	vertical : 1000
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Air carrier X at FL280 on J64 wbound reported a TCASII RA and was responding to it. Air carrier Y when I looked was level at FL290 eastbound passing over the top of X. Because of the workload I didn't catch the call sign at first. When I questioned who it was the aircraft were past each other. The aircraft were vertical separated. There was no need for an RA because the aircraft were separated by appropriate standards. The sector was busy with inbound traffic and we also had an aircraft with hydraulic problems in the sector. The TCASII incident took me away from my other tasks putting me in a panic looking and trying to find out who was responding to an RA. This incident added to the stress level and workload of the sector.

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Original NASA ASRS Text

Title: TCASII LOGIC CAUSED ACR X TO RESPOND TO TCASII RA WHEN STANDARD SEPARATION EXISTED FROM ACR Y.

Narrative: ACR X AT FL280 ON J64 WBOUND RPTED A TCASII RA AND WAS RESPONDING TO IT. ACR Y WHEN I LOOKED WAS LEVEL AT FL290 EBOUND PASSING OVER THE TOP OF X. BECAUSE OF THE WORKLOAD I DIDN'T CATCH THE CALL SIGN AT FIRST. WHEN I QUESTIONED WHO IT WAS THE ACFT WERE PAST EACH OTHER. THE ACFT WERE VERT SEPARATED. THERE WAS NO NEED FOR AN RA BECAUSE THE ACFT WERE SEPARATED BY APPROPRIATE STANDARDS. THE SECTOR WAS BUSY WITH INBOUND TFC AND WE ALSO HAD AN ACFT WITH HYD PROBS IN THE SECTOR. THE TCASII INCIDENT TOOK ME AWAY FROM MY OTHER TASKS PUTTING ME IN A PANIC LOOKING AND TRYING TO FIND OUT WHO WAS RESPONDING TO AN RA. THIS INCIDENT ADDED TO THE STRESS LEVEL AND WORKLOAD OF THE SECTOR.

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.