Altitude deviation altitude excursion during TCASII RA.

Attributes
ACN	262264
Time
Date	199401
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : bae
State Reference	WI
Altitude	msl bound lower : 23000 msl bound upper : 23300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	descent 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 : 225 flight time total : 17000 flight time type : 1700
ASRS Report	262264
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude 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	horizontal : 4500 vertical : 2300
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

While in level cruise at FL230 TCASII advised of us traffic about 15 mi ahead, 12 O'clock, 4000 ft above us but descending. We picked up the traffic visually. (Center later told us the traffic had been cleared to FL240.) as the traffic approached our 3 O'clock position the TCASII changed to a red target, red on vsi, and a resolution command of 'climb, crossing climb.' the sighted traffic was still well above us and about 3/4 mi to the right. We complied with the resolution due to the possibility of a second, unseen aircraft. Altitude deviation about 300 ft. Center said there was no other aircraft in our vicinity and the sighted traffic went by us about FL255. Given these circumstances, I feel the TCASII software/system issued a RA that was not needed, issued it far too late to have been effective (as the traffic was almost at our 3 O'clock position when the resolution was issued) and advised us to climb although a descent would have given us more clearance from the referenced traffic.

Original NASA ASRS Text

Title: ALTDEV ALT EXCURSION DURING TCASII RA.

Narrative: WHILE IN LEVEL CRUISE AT FL230 TCASII ADVISED OF US TFC ABOUT 15 MI AHEAD, 12 O'CLOCK, 4000 FT ABOVE US BUT DSNDING. WE PICKED UP THE TFC VISUALLY. (CTR LATER TOLD US THE TFC HAD BEEN CLRED TO FL240.) AS THE TFC APCHED OUR 3 O'CLOCK POS THE TCASII CHANGED TO A RED TARGET, RED ON VSI, AND A RESOLUTION COMMAND OF 'CLB, XING CLB.' THE SIGHTED TFC WAS STILL WELL ABOVE US AND ABOUT 3/4 MI TO THE R. WE COMPLIED WITH THE RESOLUTION DUE TO THE POSSIBILITY OF A SECOND, UNSEEN ACFT. ALTDEV ABOUT 300 FT. CTR SAID THERE WAS NO OTHER ACFT IN OUR VICINITY AND THE SIGHTED TFC WENT BY US ABOUT FL255. GIVEN THESE CIRCUMSTANCES, I FEEL THE TCASII SOFTWARE/SYS ISSUED A RA THAT WAS NOT NEEDED, ISSUED IT FAR TOO LATE TO HAVE BEEN EFFECTIVE (AS THE TFC WAS ALMOST AT OUR 3 O'CLOCK POS WHEN THE RESOLUTION WAS ISSUED) AND ADVISED US TO CLB ALTHOUGH A DSCNT WOULD HAVE GIVEN US MORE CLRNC FROM THE REFED TFC.

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.