Possible false TCASII alarm, possible less than standard separation in the traffic pattern.

Attributes
ACN	310542
Time
Date	199507
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dfw
State Reference	TX
Altitude	agl bound lower : 1000 agl bound upper : 1000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dfw tower : dfw tracon : grr
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	climbout : initial cruise other
Route In Use	departure other departure sid : sid enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
ASRS Report	310542
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 10000 flight time type : 4000
ASRS Report	310543
Events
Anomaly	aircraft equipment problem : less severe conflict : airborne less severe non adherence : clearance non adherence : required legal separation other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa
Resolutory Action	aircraft : equipment problem dissipated flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 5000 vertical : 100
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	other

Narrative:

We were cleared for takeoff on runway 18L at dfw with a 185 degree heading at the marker. After flaps up and climb power, we received an RA shortly after 1000 ft AGL. Target was less than 1 mi at 3 O'clock and 100 ft above. TCASII gave 1 'descend' and commanded massive (1200 ft plus) rate down. There never was another 'descend,' 'monitor vertical speed' or clear of conflict.' neither tower or departure had any traffic in our area at the time. Supplemental information from acn 310543: we never had visual contact and only had the 1 verbal command from TCASII. Departure control only had the wbound commuter on radar. Callback conversation with reporter from acn #310543 revealed the following information from 310543: the reporter was the non- flying captain on this trip. He has been so pleased with TCASII and its operation that he never considered the possibility of a false alarm. He now agrees that this could have been the situation as neither he, the flying first officer, nor ATC saw any other traffic. The WX was 'good,' he 'should have been able to see any traffic.' the TCASII was not written up in the logbook as the reporter did not consider a false alarm.

Original NASA ASRS Text

Title: POSSIBLE FALSE TCASII ALARM, POSSIBLE LTSS IN THE TFC PATTERN.

Narrative: WE WERE CLRED FOR TKOF ON RWY 18L AT DFW WITH A 185 DEG HDG AT THE MARKER. AFTER FLAPS UP AND CLB PWR, WE RECEIVED AN RA SHORTLY AFTER 1000 FT AGL. TARGET WAS LESS THAN 1 MI AT 3 O'CLOCK AND 100 FT ABOVE. TCASII GAVE 1 'DSND' AND COMMANDED MASSIVE (1200 FT PLUS) RATE DOWN. THERE NEVER WAS ANOTHER 'DSND,' 'MONITOR VERT SPD' OR CLR OF CONFLICT.' NEITHER TWR OR DEP HAD ANY TFC IN OUR AREA AT THE TIME. SUPPLEMENTAL INFO FROM ACN 310543: WE NEVER HAD VISUAL CONTACT AND ONLY HAD THE 1 VERBAL COMMAND FROM TCASII. DEP CTL ONLY HAD THE WBOUND COMMUTER ON RADAR. CALLBACK CONVERSATION WITH RPTR FROM ACN #310543 REVEALED THE FOLLOWING INFO FROM 310543: THE RPTR WAS THE NON- FLYING CAPT ON THIS TRIP. HE HAS BEEN SO PLEASED WITH TCASII AND ITS OP THAT HE NEVER CONSIDERED THE POSSIBILITY OF A FALSE ALARM. HE NOW AGREES THAT THIS COULD HAVE BEEN THE SIT AS NEITHER HE, THE FLYING FO, NOR ATC SAW ANY OTHER TFC. THE WX WAS 'GOOD,' HE 'SHOULD HAVE BEEN ABLE TO SEE ANY TFC.' THE TCASII WAS NOT WRITTEN UP IN THE LOGBOOK AS THE RPTR DID NOT CONSIDER A FALSE ALARM.

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.