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TCASII induced less than standard separation. Air carrier X TCASII RA climb had less than standard separation from air carrier Y. Evasive action taken. Pilot deviation non adherence to ATC clearance.
| Attributes | |
| ACN | 240304 |
| Time | |
| Date | 199305 |
| Day | Sat |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : sea |
| State Reference | WA |
| Altitude | msl bound lower : 10000 msl bound upper : 10000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tower : ord |
| Operator | common carrier : air carrier |
| Make Model Name | Light Transport, High Wing, 2 Turboprop Eng |
| Flight Phase | cruise other |
| Route In Use | enroute : direct enroute airway : sea |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | descent other |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| Experience | controller radar : 5 |
| ASRS Report | 240304 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance non adherence : required legal separation |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified |
| Resolutory Action | flight crew : took evasive action |
| Consequence | Other |
| Miss Distance | horizontal : 9000 vertical : 900 |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation other |
Narrative:
Air carrier X and air carrier Y both inbound on same route. Air carrier X was an light transport level at 10000 ft. Air carrier Y was an medium large transport assigned 11000 ft descending out of 12000 ft overtaking the slower air carrier X. Air carrier X advised he had climbed out of 10000 ft due to an RA on his TCASII apparently caused by a flight of 2 fgt's climbing to 9000 ft below him. The result was a loss of standard vertical separation (900 ft/air carrier X was at 11300 ft when air carrier X was at 10400 ft). This can be attributed to TCASII. Standard separation was guaranteed until TCASII reduced it.
Original NASA ASRS Text
Title: TCASII INDUCED LTSS. ACR X TCASII RA CLB HAD LTSS FROM ACR Y. EVASIVE ACTION TAKEN. PLTDEV NON ADHERENCE TO ATC CLRNC.
Narrative: ACR X AND ACR Y BOTH INBOUND ON SAME RTE. ACR X WAS AN LTT LEVEL AT 10000 FT. ACR Y WAS AN MLG ASSIGNED 11000 FT DSNDING OUT OF 12000 FT OVERTAKING THE SLOWER ACR X. ACR X ADVISED HE HAD CLBED OUT OF 10000 FT DUE TO AN RA ON HIS TCASII APPARENTLY CAUSED BY A FLT OF 2 FGT'S CLBING TO 9000 FT BELOW HIM. THE RESULT WAS A LOSS OF STANDARD VERT SEPARATION (900 FT/ACR X WAS AT 11300 FT WHEN ACR X WAS AT 10400 FT). THIS CAN BE ATTRIBUTED TO TCASII. STANDARD SEPARATION WAS GUARANTEED UNTIL TCASII REDUCED IT.
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.