An air carrier medium large transport crew descended in response to a TCASII command.

Attributes
ACN	244544
Time
Date	199306
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : rod
State Reference	OH
Altitude	msl bound lower : 27500 msl bound upper : 28000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other descent other
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other 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 : 200 flight time total : 16500 flight time type : 5100
ASRS Report	244544
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 14000 flight time type : 8000
ASRS Report	244332
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : took evasive action
Consequence	Other
Miss Distance	vertical : 1000
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

TCASII gave us a dive command. We had traffic at our 12 O'clock, descending to FL290. We were at FL280. After visually sighting our traffic, I could not determine if he had stopped at FL290 and TCASII was giving a resolution to dive. I descended 500 ft and that satisfied TCASII. No other aircraft were in the area. In the future, I will put more dependence on the altitude difference readout on the TCASII scope and will disregard the RA.

Original NASA ASRS Text

Title: AN ACR MLG CREW DSNDED IN RESPONSE TO A TCASII COMMAND.

Narrative: TCASII GAVE US A DIVE COMMAND. WE HAD TFC AT OUR 12 O'CLOCK, DSNDING TO FL290. WE WERE AT FL280. AFTER VISUALLY SIGHTING OUR TFC, I COULD NOT DETERMINE IF HE HAD STOPPED AT FL290 AND TCASII WAS GIVING A RESOLUTION TO DIVE. I DSNDED 500 FT AND THAT SATISFIED TCASII. NO OTHER ACFT WERE IN THE AREA. IN THE FUTURE, I WILL PUT MORE DEPENDENCE ON THE ALT DIFFERENCE READOUT ON THE TCASII SCOPE AND WILL DISREGARD THE 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.