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Near midair collision between a B757 on a STAR arrival in mountainous terrain and a small aircraft traversing a gap in the mountains. The B757 flight crew took evasive action in response to a TCASII RA.
| Attributes | |
| ACN | 429500 |
| Time | |
| Date | 199902 |
| Day | Fri |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : sna.airport |
| State Reference | CA |
| Altitude | msl single value : 5400 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : sct.tracon tower : dtw.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B757 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : intermediate altitude |
| Route In Use | arrival star : kayoh4 |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time total : 12000 flight time type : 180 |
| ASRS Report | 429500 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : multi engine pilot : commercial pilot : instrument |
| Events | |
| Anomaly | conflict : nmac |
| Independent Detector | aircraft equipment : tcas other flight crewa |
| Resolutory Action | flight crew : took evasive action |
| Miss Distance | horizontal : 0 vertical : 500 |
| Supplementary | |
| Problem Areas | Airspace Structure Flight Crew Human Performance ATC Human Performance |
| Primary Problem | Flight Crew Human Performance |
Narrative:
Although conflicts with light aircraft can occur anywhere, this successful RA maneuver was required to some extent by an unusual arrival into the sna area. This arrival was much further north of the kayoh waypoint. This put us heading through a gap in the mountain ridges to the east of sna rather than over the top of the ridges the kayoh arrival bring you over. The problem seems to be that light planes use this gap for their eastbound flts. The arrival we were being vectored, puts us in closer proximity to light plane conflict. We were a medical flight and I wonder whether that was the reason for this more northerly, but more direct route to snake. It would, however, be a safer operation to keep commercial and private aircraft better separated, in what is a heavy traffic area, by sticking to the kayoh arrival.
Original NASA ASRS Text
Title: NMAC BTWN A B757 ON A STAR ARR IN MOUNTAINOUS TERRAIN AND A SMALL ACFT TRAVERSING A GAP IN THE MOUNTAINS. THE B757 FLC TOOK EVASIVE ACTION IN RESPONSE TO A TCASII RA.
Narrative: ALTHOUGH CONFLICTS WITH LIGHT ACFT CAN OCCUR ANYWHERE, THIS SUCCESSFUL RA MANEUVER WAS REQUIRED TO SOME EXTENT BY AN UNUSUAL ARR INTO THE SNA AREA. THIS ARR WAS MUCH FURTHER N OF THE KAYOH WAYPOINT. THIS PUT US HDG THROUGH A GAP IN THE MOUNTAIN RIDGES TO THE E OF SNA RATHER THAN OVER THE TOP OF THE RIDGES THE KAYOH ARR BRING YOU OVER. THE PROB SEEMS TO BE THAT LIGHT PLANES USE THIS GAP FOR THEIR EBOUND FLTS. THE ARR WE WERE BEING VECTORED, PUTS US IN CLOSER PROX TO LIGHT PLANE CONFLICT. WE WERE A MEDICAL FLT AND I WONDER WHETHER THAT WAS THE REASON FOR THIS MORE NORTHERLY, BUT MORE DIRECT RTE TO SNAKE. IT WOULD, HOWEVER, BE A SAFER OP TO KEEP COMMERCIAL AND PVT ACFT BETTER SEPARATED, IN WHAT IS A HVY TFC AREA, BY STICKING TO THE KAYOH ARR.
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.