Altitude deviation excursion in flight crew response to TCASII RA.

Attributes
ACN	285235
Time
Date	199410
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : dfw
State Reference	TX
Altitude	msl bound lower : 1500 msl bound upper : 2300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dfw
Operator	common carrier : air carrier
Make Model Name	Saab-Scania Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : commercial pilot : instrument
Experience	flight time last 90 days : 240 flight time total : 6000 flight time type : 4000
ASRS Report	285235
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 8000 flight time type : 3000
ASRS Report	284954
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera
Resolutory Action	flight crew : took evasive action flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

After departing runway 36R from dfw tower handed us over to departure. Departure gave us a heading of 240 degrees and climb to 3000 ft. At 2300 ft we received an RA from our TCASII. The rate of descent required by the TCASII RA was 2200 FPM. The TCASII screen showed a target right on top of us at our altitude. A descent was immediately begun (I, the first officer flying) as instructed by the TCASII. The captain immediately informed departure we were descending in response to an RA. The controller told us there was nothing out there.' as we descended the traffic continued to match our altitude and the RA continued. As we approached 1500 ft MSL the controller told us to immediately climb as he was receiving an altitude alert on us. Again we replied no because we were still following our RA we were VMC, so there was never a danger of inadvertently flying into the ground. The controller insisted we climb. We decided at this point, since we have yet to see the intruder and even with our 2200 FPM rate of descent 'he' had continued to stay at our altitude, that it must be a false target. We then initiated a climb. The 'intruder' followed us up matching our altitude. We turned the TCASII to TA only and climbed to 3000 ft. Upon reaching 3000 ft, the target disappeared. We both believe the target issued on the TCASII was in fact ourselves. Supplemental information from acn 284954: the crew believes this event to be false but when you get an RA you don't know if it is real or not you just follow it. I still believe TCASII to be invaluable.

Original NASA ASRS Text

Title: ALTDEV EXCURSION IN FLC RESPONSE TO TCASII RA.

Narrative: AFTER DEPARTING RWY 36R FROM DFW TWR HANDED US OVER TO DEP. DEP GAVE US A HDG OF 240 DEGS AND CLB TO 3000 FT. AT 2300 FT WE RECEIVED AN RA FROM OUR TCASII. THE RATE OF DSCNT REQUIRED BY THE TCASII RA WAS 2200 FPM. THE TCASII SCREEN SHOWED A TARGET R ON TOP OF US AT OUR ALT. A DSCNT WAS IMMEDIATELY BEGUN (I, THE FO FLYING) AS INSTRUCTED BY THE TCASII. THE CAPT IMMEDIATELY INFORMED DEP WE WERE DSNDING IN RESPONSE TO AN RA. THE CTLR TOLD US THERE WAS NOTHING OUT THERE.' AS WE DSNDED THE TFC CONTINUED TO MATCH OUR ALT AND THE RA CONTINUED. AS WE APCHED 1500 FT MSL THE CTLR TOLD US TO IMMEDIATELY CLB AS HE WAS RECEIVING AN ALT ALERT ON US. AGAIN WE REPLIED NO BECAUSE WE WERE STILL FOLLOWING OUR RA WE WERE VMC, SO THERE WAS NEVER A DANGER OF INADVERTENTLY FLYING INTO THE GND. THE CTLR INSISTED WE CLB. WE DECIDED AT THIS POINT, SINCE WE HAVE YET TO SEE THE INTRUDER AND EVEN WITH OUR 2200 FPM RATE OF DSCNT 'HE' HAD CONTINUED TO STAY AT OUR ALT, THAT IT MUST BE A FALSE TARGET. WE THEN INITIATED A CLB. THE 'INTRUDER' FOLLOWED US UP MATCHING OUR ALT. WE TURNED THE TCASII TO TA ONLY AND CLBED TO 3000 FT. UPON REACHING 3000 FT, THE TARGET DISAPPEARED. WE BOTH BELIEVE THE TARGET ISSUED ON THE TCASII WAS IN FACT OURSELVES. SUPPLEMENTAL INFO FROM ACN 284954: THE CREW BELIEVES THIS EVENT TO BE FALSE BUT WHEN YOU GET AN RA YOU DON'T KNOW IF IT IS REAL OR NOT YOU JUST FOLLOW IT. I STILL BELIEVE TCASII TO BE INVALUABLE.

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.