Flight crew of air carrier large transport aircraft deviated from assigned altitude in response to a...

Attributes
ACN	223205
Time
Date	199210
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : alo
State Reference	IA
Altitude	msl bound lower : 26500 msl bound upper : 28000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zau
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other
Flight Plan	IFR
Aircraft 2
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : commercial pilot : cfi pilot : atp pilot : instrument
Experience	flight time last 90 days : 210 flight time total : 14000
ASRS Report	223205
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial pilot : instrument
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 other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 500 vertical : 1000
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

TCASII properly idented traffic. TCASII could not anticipate traffic would level 1000 ft above us and we had no way in night VMC to determine closing acfts altitude visually. ATC did not call traffic for us. TCASII went into RA mode and commanded a 1500 FPM descent which we complied with. We descended from assigned altitude of FL280 to FL26.5 until receiving a clear of conflict from TCASII. Advised ATC of the RA and our deviation. Controller ordered us back to FL280. I did not comply until TCASII gave a clear of conflict aural alert. I feel we had no choice but to comply with TCASII RA.

Original NASA ASRS Text

Title: FLC OF ACR LGT ACFT DEVIATED FROM ASSIGNED ALT IN RESPONSE TO A TCASII RA.

Narrative: TCASII PROPERLY IDENTED TFC. TCASII COULD NOT ANTICIPATE TFC WOULD LEVEL 1000 FT ABOVE US AND WE HAD NO WAY IN NIGHT VMC TO DETERMINE CLOSING ACFTS ALT VISUALLY. ATC DID NOT CALL TFC FOR US. TCASII WENT INTO RA MODE AND COMMANDED A 1500 FPM DSCNT WHICH WE COMPLIED WITH. WE DSNDED FROM ASSIGNED ALT OF FL280 TO FL26.5 UNTIL RECEIVING A CLR OF CONFLICT FROM TCASII. ADVISED ATC OF THE RA AND OUR DEV. CTLR ORDERED US BACK TO FL280. I DID NOT COMPLY UNTIL TCASII GAVE A CLR OF CONFLICT AURAL ALERT. I FEEL WE HAD NO CHOICE BUT TO COMPLY WITH TCASII RA.

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.

Flight crew of air carrier large transport aircraft deviated from assigned altitude in response to a TCASII RA.