An air carrier medium large transport ignored a TCASII command.

Attributes
ACN	256728
Time
Date	199311
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : dxo airport : dtw
State Reference	MI
Altitude	msl bound lower : 11000 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : dtw tower : pwm
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 250 flight time total : 6500 flight time type : 3000
ASRS Report	256728
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe other anomaly other other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Miss Distance	horizontal : 0 vertical : 1000
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

Approaching dtw from southeast. Vectored over field for right base for runway 21R. About 5-6 southeast of field, received TA, then RA TCASII from aircraft departing runway 21 and climbing out southeast. Captain PF took no action to comply with RA and directed first officer to request permission from approach control to deviate from altitude. Captain probably had an aircraft in sight at 12 O'clock (there were at least 10 to choose from) and determined there was no conflict. Question: 1) how do you determine with 100 percent probability the aircraft in sight is the intruder causing the RA? 2) can a TCASII RA be disregarded? Is it not a required maneuver. Callback conversation with reporter revealed the following information: the reporter is a retired fighter pilot from the air force. He believes that TCASII is even better than the radar that he carried around in his air defense fighter. He believes that all TCASII commands should be followed without question. This grizzled veteran analyst tried to disabuse him from that notion.

Original NASA ASRS Text

Title: AN ACR MLG IGNORED A TCASII COMMAND.

Narrative: APCHING DTW FROM SE. VECTORED OVER FIELD FOR R BASE FOR RWY 21R. ABOUT 5-6 SE OF FIELD, RECEIVED TA, THEN RA TCASII FROM ACFT DEPARTING RWY 21 AND CLBING OUT SE. CAPT PF TOOK NO ACTION TO COMPLY WITH RA AND DIRECTED FO TO REQUEST PERMISSION FROM APCH CTL TO DEVIATE FROM ALT. CAPT PROBABLY HAD AN ACFT IN SIGHT AT 12 O'CLOCK (THERE WERE AT LEAST 10 TO CHOOSE FROM) AND DETERMINED THERE WAS NO CONFLICT. QUESTION: 1) HOW DO YOU DETERMINE WITH 100 PERCENT PROBABILITY THE ACFT IN SIGHT IS THE INTRUDER CAUSING THE RA? 2) CAN A TCASII RA BE DISREGARDED? IS IT NOT A REQUIRED MANEUVER. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR IS A RETIRED FIGHTER PLT FROM THE AIR FORCE. HE BELIEVES THAT TCASII IS EVEN BETTER THAN THE RADAR THAT HE CARRIED AROUND IN HIS AIR DEFENSE FIGHTER. HE BELIEVES THAT ALL TCASII COMMANDS SHOULD BE FOLLOWED WITHOUT QUESTION. THIS GRIZZLED VETERAN ANALYST TRIED TO DISABUSE HIM FROM THAT NOTION.

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.