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An IFR large transport had a TCASII climb command caused by a VFR small aircraft in mixed WX conditions.
| Attributes | |
| ACN | 219845 |
| Time | |
| Date | 199208 |
| Day | Sun |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : hou |
| State Reference | TX |
| Altitude | msl bound lower : 7500 msl bound upper : 8000 |
| Environment | |
| Flight Conditions | Mixed |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | Large Transport, Low Wing, 3 Turbojet Eng |
| Flight Phase | cruise other descent other |
| Route In Use | enroute : on vectors enroute airway : hou |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Small Aircraft |
| Flight Phase | cruise other |
| Flight Plan | VFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : flight engineer pilot : instrument |
| Experience | flight time last 90 days : 165 flight time total : 2000 flight time type : 490 |
| ASRS Report | 219845 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : flight engineer pilot : commercial pilot : instrument pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 9000 flight time type : 200 |
| ASRS Report | 219580 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course flight crew : took evasive action other |
| Consequence | Other |
| Miss Distance | horizontal : 3000 vertical : 500 |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation other |
Narrative:
While on descent to 8000 ft, TCASII issued a 'traffic, traffic' alert. VFR aircraft was observed at our 2-2:30 position. Aircraft appeared to be climbing towards us near our altitude. Decision was made to continue descent to avoid. TCASII then issued 'climb' directive. Climbed to 8000 ft immediately upon directive. Traffic was avoided. Approach frequency became blocked by a 'hot microphone' and an alternate approach frequency was selected before controller was advised of the TCASII directive. Uneventful landing followed. Supplemental information from acn 219581: a transmission was made by another aircraft that they had deviated for WX and could not be violated because they were VFR. I assumed this call was made by our traffic. In my opinion, the problem was caused by light, VFR aircraft deviation for WX. Our response was to maintain TCASII and visual separation. A traffic call from approach control would solve problem.
Original NASA ASRS Text
Title: AN IFR LGT HAD A TCASII CLB COMMAND CAUSED BY A VFR SMA IN MIXED WX CONDITIONS.
Narrative: WHILE ON DSCNT TO 8000 FT, TCASII ISSUED A 'TFC, TFC' ALERT. VFR ACFT WAS OBSERVED AT OUR 2-2:30 POS. ACFT APPEARED TO BE CLBING TOWARDS US NEAR OUR ALT. DECISION WAS MADE TO CONTINUE DSCNT TO AVOID. TCASII THEN ISSUED 'CLB' DIRECTIVE. CLBED TO 8000 FT IMMEDIATELY UPON DIRECTIVE. TFC WAS AVOIDED. APCH FREQ BECAME BLOCKED BY A 'HOT MICROPHONE' AND AN ALTERNATE APCH FREQ WAS SELECTED BEFORE CTLR WAS ADVISED OF THE TCASII DIRECTIVE. UNEVENTFUL LNDG FOLLOWED. SUPPLEMENTAL INFO FROM ACN 219581: A XMISSION WAS MADE BY ANOTHER ACFT THAT THEY HAD DEVIATED FOR WX AND COULD NOT BE VIOLATED BECAUSE THEY WERE VFR. I ASSUMED THIS CALL WAS MADE BY OUR TFC. IN MY OPINION, THE PROBLEM WAS CAUSED BY LIGHT, VFR ACFT DEV FOR WX. OUR RESPONSE WAS TO MAINTAIN TCASII AND VISUAL SEPARATION. A TFC CALL FROM APCH CTL WOULD SOLVE PROBLEM.
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.