TCASII altitude deviation in holding pattern.

Attributes
ACN	274661
Time
Date	199406
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : hmv
State Reference	TN
Altitude	msl bound lower : 25600 msl bound upper : 26000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 180 flight time total : 6000 flight time type : 2500
ASRS Report	274661
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 180 flight time total : 10360 flight time type : 8000
ASRS Report	274130
Events
Anomaly	altitude deviation : overshoot altitude deviation : excursion from assigned altitude non adherence : required legal separation non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

Flight cmh to clt, holding instructions issued by ATC center to hold at hmv VOR north 360 degrees right, 10 mi legs right turns FL260, efc XA50 Z. At approximately XA47 and in about our 3RD turn inbound to hmz, TCASII issued TA. We had heard ATC instructions to intruder aircraft to descend to FL270 TA. Turned to RA to 'descend' traffic was approximately 800 ft above us and descending into our flight path. I disengaged the autoplt and initiated descent according to TCASII commands. At approximately FL257, captain visually acquired intruder traffic and halted descent for concern for possible traffic holding below us. Descent halted at approximately FL256. TCASII indicated intruder was 800 ft above us. TCASII was still issuing descent commands, (aural and visual). Intruder then went back to FL270, and we returned to FL260. Captain notified atl center that we had a TCASII descent command and deviation. Center was very busy with numerous other traffic deviating for WX and holding. Contributing to this was numerous company aircraft with like call signs, such as air carrier xxa, air carrier xxc, air carrier xxd, etc. Nothing was mentioned by center as to our altitude deviation to avoid intruder aircraft or to other aircraft concerning this matter. We were issued a heading to depart the hold, then switched to clt approach. Supplemental information from acn 274130: at FL257 I acquired traffic visually and stopped aircraft at FL256. TCASII indicated traffic at 800 ft above us (FL264). TCASII was still issuing us a maximum descent.

Original NASA ASRS Text

Title: TCASII ALTDEV IN HOLDING PATTERN.

Narrative: FLT CMH TO CLT, HOLDING INSTRUCTIONS ISSUED BY ATC CTR TO HOLD AT HMV VOR N 360 DEGS R, 10 MI LEGS R TURNS FL260, EFC XA50 Z. AT APPROX XA47 AND IN ABOUT OUR 3RD TURN INBOUND TO HMZ, TCASII ISSUED TA. WE HAD HEARD ATC INSTRUCTIONS TO INTRUDER ACFT TO DSND TO FL270 TA. TURNED TO RA TO 'DSND' TFC WAS APPROX 800 FT ABOVE US AND DSNDING INTO OUR FLT PATH. I DISENGAGED THE AUTOPLT AND INITIATED DSCNT ACCORDING TO TCASII COMMANDS. AT APPROX FL257, CAPT VISUALLY ACQUIRED INTRUDER TFC AND HALTED DSCNT FOR CONCERN FOR POSSIBLE TFC HOLDING BELOW US. DSCNT HALTED AT APPROX FL256. TCASII INDICATED INTRUDER WAS 800 FT ABOVE US. TCASII WAS STILL ISSUING DSCNT COMMANDS, (AURAL AND VISUAL). INTRUDER THEN WENT BACK TO FL270, AND WE RETURNED TO FL260. CAPT NOTIFIED ATL CTR THAT WE HAD A TCASII DSCNT COMMAND AND DEV. CTR WAS VERY BUSY WITH NUMEROUS OTHER TFC DEVIATING FOR WX AND HOLDING. CONTRIBUTING TO THIS WAS NUMEROUS COMPANY ACFT WITH LIKE CALL SIGNS, SUCH AS ACR XXA, ACR XXC, ACR XXD, ETC. NOTHING WAS MENTIONED BY CTR AS TO OUR ALTDEV TO AVOID INTRUDER ACFT OR TO OTHER ACFT CONCERNING THIS MATTER. WE WERE ISSUED A HDG TO DEPART THE HOLD, THEN SWITCHED TO CLT APCH. SUPPLEMENTAL INFO FROM ACN 274130: AT FL257 I ACQUIRED TFC VISUALLY AND STOPPED ACFT AT FL256. TCASII INDICATED TFC AT 800 FT ABOVE US (FL264). TCASII WAS STILL ISSUING US A MAX DSCNT.

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.