Altitude deviation altitude excursion after air carrier large transport receives a TCASII RA.

Attributes
ACN	240153
Time
Date	199304
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : mco
State Reference	FL
Altitude	msl bound lower : 10000 msl bound upper : 10500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : mco
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	general aviation : corporate
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 200 flight time total : 15500 flight time type : 2500
ASRS Report	240153
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 6000 vertical : 1500
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

After being switched to approach control (orlando) and on vectors toward the downwind for landing north, runway 36R, we received a TA from approach control who advised of approaching traffic, an light transport jet Y, climbing to 9000 ft. We were then leveling at 10000 ft, a gradual descent and step-down from cruise at 37000 ft. While trying to visually acquire the traffic, our TCASII system issued an RA and commanded a climb at 1000-1500 FPM. We did not have the approaching traffic visually and obeyed the climb command to 10500 ft, at which time the RA was resolved and the first officer saw the traffic at about 2 O'clock, approximately 1 mi away. Altitude deviation reported to approach control and descended back to 10000 ft. Landing accomplished with no further complications. Problems with TCASII in my opinion: while we were just breaking a descent, and apparently the light transport Y was discontinuing climb to level at 9000 ft, the TCASII system had no way of knowing these intentions, and thus indicated a possible conflict. Without seeing the traffic, we had no choice but to obey.

Original NASA ASRS Text

Title: ALTDEV ALT EXCURSION AFTER ACR LGT RECEIVES A TCASII RA.

Narrative: AFTER BEING SWITCHED TO APCH CTL (ORLANDO) AND ON VECTORS TOWARD THE DOWNWIND FOR LNDG N, RWY 36R, WE RECEIVED A TA FROM APCH CTL WHO ADVISED OF APCHING TFC, AN LTT JET Y, CLBING TO 9000 FT. WE WERE THEN LEVELING AT 10000 FT, A GRADUAL DSCNT AND STEP-DOWN FROM CRUISE AT 37000 FT. WHILE TRYING TO VISUALLY ACQUIRE THE TFC, OUR TCASII SYS ISSUED AN RA AND COMMANDED A CLB AT 1000-1500 FPM. WE DID NOT HAVE THE APCHING TFC VISUALLY AND OBEYED THE CLB COMMAND TO 10500 FT, AT WHICH TIME THE RA WAS RESOLVED AND THE FO SAW THE TFC AT ABOUT 2 O'CLOCK, APPROX 1 MI AWAY. ALTDEV RPTED TO APCH CTL AND DSNDED BACK TO 10000 FT. LNDG ACCOMPLISHED WITH NO FURTHER COMPLICATIONS. PROBS WITH TCASII IN MY OPINION: WHILE WE WERE JUST BREAKING A DSCNT, AND APPARENTLY THE LTT Y WAS DISCONTINUING CLB TO LEVEL AT 9000 FT, THE TCASII SYS HAD NO WAY OF KNOWING THESE INTENTIONS, AND THUS INDICATED A POSSIBLE CONFLICT. WITHOUT SEEING THE TFC, WE HAD NO CHOICE BUT TO OBEY.

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.