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Flight crew of a B737-400 climbed in response to a TCASII RA during a vector for the downwind leg. Approach controller gave TA. Reporting captain questioned the other aircraft's altimeter setting since ATC's altitude readout for the other aircraft was different than the reporter's TCASII indication as relative to their altimeter.
| Attributes | |
| ACN | 427266 |
| Time | |
| Date | 199901 |
| Day | Thu |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : sna |
| State Reference | CA |
| Altitude | msl bound lower : 5000 msl bound upper : 5600 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737-400 |
| Navigation In Use | Other |
| Route In Use | arrival other enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Cessna Single Piston Undifferentiated or Other Model |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : flight engineer |
| Experience | flight time last 90 days : 190 flight time total : 14000 flight time type : 10000 |
| ASRS Report | 427266 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial |
| Events | |
| Anomaly | conflict : airborne less severe other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : took evasive action flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Miss Distance | horizontal : 3000 vertical : 500 |
| Supplementary | |
| Air Traffic Incident | other |
Narrative:
Approaching shoreline nebound vector to downwind for runway 19R at john wayne airport (orange county), level at 5000 ft MSL. I noted TCASII traffic passing right to left ahead about 3 mi indicating 300 ft below (-03) or 4700 ft. Socal advised. We initially did not see traffic. A TCASII TA transitioned to an RA. TCASII indicated aircraft 200 ft below (-02) 4800 ft and slightly to right. PF (first officer) responded to RA initially climbing to 5600 ft and then returning to altitude when clear of conflict. Socal queried traffic and traffic responded he was at 4500 ft. First officer saw traffic after responding to TCASII RA. Question: local altimeter was 30.17. Could conflicting traffic have misset altimeter? Could this result in the apparent discrepancy in crossing altitudes between our TCASII display and what socal approach saw on radar?
Original NASA ASRS Text
Title: FLC OF A B737-400 CLBED IN RESPONSE TO A TCASII RA DURING A VECTOR FOR THE DOWNWIND LEG. APCH CTLR GAVE TA. RPTING CAPT QUESTIONED THE OTHER ACFT'S ALTIMETER SETTING SINCE ATC'S ALT READOUT FOR THE OTHER ACFT WAS DIFFERENT THAN THE RPTR'S TCASII INDICATION AS RELATIVE TO THEIR ALTIMETER.
Narrative: APCHING SHORELINE NEBOUND VECTOR TO DOWNWIND FOR RWY 19R AT JOHN WAYNE ARPT (ORANGE COUNTY), LEVEL AT 5000 FT MSL. I NOTED TCASII TFC PASSING R TO L AHEAD ABOUT 3 MI INDICATING 300 FT BELOW (-03) OR 4700 FT. SOCAL ADVISED. WE INITIALLY DID NOT SEE TFC. A TCASII TA TRANSITIONED TO AN RA. TCASII INDICATED ACFT 200 FT BELOW (-02) 4800 FT AND SLIGHTLY TO R. PF (FO) RESPONDED TO RA INITIALLY CLBING TO 5600 FT AND THEN RETURNING TO ALT WHEN CLR OF CONFLICT. SOCAL QUERIED TFC AND TFC RESPONDED HE WAS AT 4500 FT. FO SAW TFC AFTER RESPONDING TO TCASII RA. QUESTION: LCL ALTIMETER WAS 30.17. COULD CONFLICTING TFC HAVE MISSET ALTIMETER? COULD THIS RESULT IN THE APPARENT DISCREPANCY IN XING ALTS BTWN OUR TCASII DISPLAY AND WHAT SOCAL APCH SAW ON RADAR?
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.