B727 takes evasive action in response to TCASII RA while holding in ZOB airspace.

Attributes
ACN	427701
Time
Date	199902
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mbs
State Reference	MI
Altitude	msl bound lower : 15500 msl bound upper : 16000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : cak.tower
Operator	common carrier : air carrier
Flight Phase	cruise other other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Flight Phase	descent other other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 210 flight time total : 9000
ASRS Report	427761
Person 2
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : instrument pilot : flight engineer pilot : commercial
Experience	flight time last 90 days : 220 flight time total : 5000 flight time type : 2000
ASRS Report	428212
Events
Anomaly	altitude deviation : overshoot conflict : ground less severe conflict : airborne less severe other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Consequence	Other
Miss Distance	horizontal : 4500 vertical : 500
Supplementary
Air Traffic Incident	Pilot Deviation

Narrative:

While holding at polar intersection (dtw arrival fix, approximately 40 DME northwest dtw), intruder aircraft descended directly toward us, causing a TCASII RA. Had to take evasive action and TCASII showed 500 ft separation and less than 1 mi horizontal. ATC notified. Descended 400-500 ft for RA. Supplemental information from acn 427943: we were holding at polar intersection inbound leg to dtw at FL190. Misinterped controller descent clearance to 13000 ft when cleared to 17000 ft. Noted traffic on TCASII, inquired ATC and immediately recovered to 17000 ft. TCASII RA was followed. PNF was receiving ATIS and did not hear original ATC call for altitude of 17000 ft.

Original NASA ASRS Text

Title: B727 TAKES EVASIVE ACTION IN RESPONSE TO TCASII RA WHILE HOLDING IN ZOB AIRSPACE.

Narrative: WHILE HOLDING AT POLAR INTXN (DTW ARR FIX, APPROX 40 DME NW DTW), INTRUDER ACFT DSNDED DIRECTLY TOWARD US, CAUSING A TCASII RA. HAD TO TAKE EVASIVE ACTION AND TCASII SHOWED 500 FT SEPARATION AND LESS THAN 1 MI HORIZ. ATC NOTIFIED. DSNDED 400-500 FT FOR RA. SUPPLEMENTAL INFO FROM ACN 427943: WE WERE HOLDING AT POLAR INTXN INBOUND LEG TO DTW AT FL190. MISINTERPED CTLR DSCNT CLRNC TO 13000 FT WHEN CLRED TO 17000 FT. NOTED TFC ON TCASII, INQUIRED ATC AND IMMEDIATELY RECOVERED TO 17000 FT. TCASII RA WAS FOLLOWED. PNF WAS RECEIVING ATIS AND DID NOT HEAR ORIGINAL ATC CALL FOR ALT OF 17000 FT.

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.