DC9 crew had TCASII RA in ZOB class a.

Attributes
ACN	490499
Time
Date	200010
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : djb.vortac
State Reference	OH
Altitude	msl bound lower : 23400 msl bound upper : 24000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob.artcc tower : bdr.tower
Operator	common carrier : air carrier
Make Model Name	DC-9 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zob.artcc
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	descent : vacating altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 200 flight time total : 15000 flight time type : 200
ASRS Report	490499
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : cfi pilot : atp
Experience	flight time last 90 days : 250 flight time total : 6200 flight time type : 900
ASRS Report	490860
Events
Anomaly	non adherence : required legal separation
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action
Miss Distance	vertical : 1100
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Ambiguous

Narrative:

Received TCASII RA while cruising at FL240. The TCASII commanded a descent which we initiated to approximately 23400 ft. Notified ZOB of the RA and our corrective action. We never saw the other aircraft that appeared on TCASII and caused the RA. Supplemental information from acn 490860: opposing traffic was descending into us rapidly, and closing rapidly. We were cruising at FL240. TCASII commanded a descent RA and we descended approximately 600 ft. TCASII called 'clear of conflict' and we returned to FL240. ARTCC did not seem to understand our call of descent due to TCASII RA initially. We explained again, and they informed us of additional traffic at FL230. We never saw the other aircraft.

Original NASA ASRS Text

Title: DC9 CREW HAD TCASII RA IN ZOB CLASS A.

Narrative: RECEIVED TCASII RA WHILE CRUISING AT FL240. THE TCASII COMMANDED A DSCNT WHICH WE INITIATED TO APPROX 23400 FT. NOTIFIED ZOB OF THE RA AND OUR CORRECTIVE ACTION. WE NEVER SAW THE OTHER ACFT THAT APPEARED ON TCASII AND CAUSED THE RA. SUPPLEMENTAL INFO FROM ACN 490860: OPPOSING TFC WAS DSNDING INTO US RAPIDLY, AND CLOSING RAPIDLY. WE WERE CRUISING AT FL240. TCASII COMMANDED A DSCNT RA AND WE DSNDED APPROX 600 FT. TCASII CALLED 'CLR OF CONFLICT' AND WE RETURNED TO FL240. ARTCC DID NOT SEEM TO UNDERSTAND OUR CALL OF DSCNT DUE TO TCASII RA INITIALLY. WE EXPLAINED AGAIN, AND THEY INFORMED US OF ADDITIONAL TFC AT FL230. WE NEVER SAW THE OTHER ACFT.

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.