First officer of air carrier medium large transport aircraft deviated from assigned altitude in resp...

Attributes
ACN	223028
Time
Date	199210
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : sat
State Reference	TX
Altitude	msl bound lower : 12000 msl bound upper : 13000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sat
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival other arrival star : star enroute airway : sat
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : flight engineer pilot : commercial
Experience	flight time last 90 days : 200 flight time total : 3000 flight time type : 200
ASRS Report	223028
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : instrument pilot : atp
Experience	flight time last 90 days : 240 flight time total : 11483 flight time type : 975
ASRS Report	223189
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	atc equipment other atc equipment : unspecified aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew faa : investigated
Miss Distance	horizontal : 0 vertical : 600
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Event occurred on our atl to sat leg while flying the marcs 1 arrival from industry. We had leveled at 12000 ft to cross marcs and I was flying the aircraft (medium large transport) via the autoplt. I had begun to slow to 250 as we turned to criss. Approach control called VFR traffic at 11.5 at 12-1 O'clock and then asked if we wanted to land on 12R or 21 -- winds 210 at 10. The captain replied 'standby' and told me we should look for the traffic. We were both looking outside for a nose-on (small aircraft) when the TCASII alerted 'traffic, traffic.' I looked at the TCASII symbology and saw the yellow circle at approximately 2 mi on the nose. I was quite concerned (142 people on board) and continued to look outside. In a matter of seconds the TCASII went to a TA 'climb, climb' with a green arc at approximately 2000 FPM. In accordance with company policy and my belief that inaction would be wrong, I immediately disengaged the autoplt and hand-flew the RA to 2000 FPM. As soon as TCASII alerted 'clear of conflict,' I slowly nosed over to begin a descent. I tried to make this maneuver as smooth as possible and I'm not completely sure how high we got. I believe I started the nose over at approximately 13000 ft. Approach asked why we did this, since they called out the traffic. Quite simply, I didn't see the traffic and I wouldn't bet 142 passenger plus 6 crew that the VFR traffic was at 11.5. I would do the same again. Sat approach filed an altitude deviation. Additional considerations: will VFR traffic at 500 ft separation always give a TCASII RA? If so, should pilots not in visual contact with the VFR traffic comply with the RA? It would seem to me that 500 ft separation simply is not comfortable and approach should vector IFR carriers away from known VFR traffic in radio contact if the separation will be 500 ft. San antonio approach was upset that we deviated, but in my mind there was no other possible action unless I had a visual.

Original NASA ASRS Text

Title: FO OF ACR MLG ACFT DEVIATED FROM ASSIGNED ALT IN RESPONSE TO A TCASII RA.

Narrative: EVENT OCCURRED ON OUR ATL TO SAT LEG WHILE FLYING THE MARCS 1 ARR FROM INDUSTRY. WE HAD LEVELED AT 12000 FT TO CROSS MARCS AND I WAS FLYING THE ACFT (MLG) VIA THE AUTOPLT. I HAD BEGUN TO SLOW TO 250 AS WE TURNED TO CRISS. APCH CTL CALLED VFR TFC AT 11.5 AT 12-1 O'CLOCK AND THEN ASKED IF WE WANTED TO LAND ON 12R OR 21 -- WINDS 210 AT 10. THE CAPT REPLIED 'STANDBY' AND TOLD ME WE SHOULD LOOK FOR THE TFC. WE WERE BOTH LOOKING OUTSIDE FOR A NOSE-ON (SMA) WHEN THE TCASII ALERTED 'TFC, TFC.' I LOOKED AT THE TCASII SYMBOLOGY AND SAW THE YELLOW CIRCLE AT APPROX 2 MI ON THE NOSE. I WAS QUITE CONCERNED (142 PEOPLE ON BOARD) AND CONTINUED TO LOOK OUTSIDE. IN A MATTER OF SECONDS THE TCASII WENT TO A TA 'CLB, CLB' WITH A GREEN ARC AT APPROX 2000 FPM. IN ACCORDANCE WITH COMPANY POLICY AND MY BELIEF THAT INACTION WOULD BE WRONG, I IMMEDIATELY DISENGAGED THE AUTOPLT AND HAND-FLEW THE RA TO 2000 FPM. AS SOON AS TCASII ALERTED 'CLR OF CONFLICT,' I SLOWLY NOSED OVER TO BEGIN A DSCNT. I TRIED TO MAKE THIS MANEUVER AS SMOOTH AS POSSIBLE AND I'M NOT COMPLETELY SURE HOW HIGH WE GOT. I BELIEVE I STARTED THE NOSE OVER AT APPROX 13000 FT. APCH ASKED WHY WE DID THIS, SINCE THEY CALLED OUT THE TFC. QUITE SIMPLY, I DIDN'T SEE THE TFC AND I WOULDN'T BET 142 PAX PLUS 6 CREW THAT THE VFR TFC WAS AT 11.5. I WOULD DO THE SAME AGAIN. SAT APCH FILED AN ALTDEV. ADDITIONAL CONSIDERATIONS: WILL VFR TFC AT 500 FT SEPARATION ALWAYS GIVE A TCASII RA? IF SO, SHOULD PLTS NOT IN VISUAL CONTACT WITH THE VFR TFC COMPLY WITH THE RA? IT WOULD SEEM TO ME THAT 500 FT SEPARATION SIMPLY IS NOT COMFORTABLE AND APCH SHOULD VECTOR IFR CARRIERS AWAY FROM KNOWN VFR TFC IN RADIO CONTACT IF THE SEPARATION WILL BE 500 FT. SAN ANTONIO APCH WAS UPSET THAT WE DEVIATED, BUT IN MY MIND THERE WAS NO OTHER POSSIBLE ACTION UNLESS I HAD A VISUAL.

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.

First officer of air carrier medium large transport aircraft deviated from assigned altitude in response to a TCASII RA.