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Light transport Y altitude deviation altitude overshot descent through occupied altitude of air carrier X. Less than standard separation.
| Attributes | |
| ACN | 128222 |
| Time | |
| Date | 198911 |
| Day | Thu |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : srp |
| State Reference | AZ |
| Altitude | msl bound lower : 37000 msl bound upper : 37000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zab |
| Operator | common carrier : air carrier |
| Make Model Name | Widebody, Low Wing, 3 Turbojet Eng |
| Navigation In Use | Other |
| Flight Phase | cruise other |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | general aviation : corporate |
| Make Model Name | Light Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | descent other |
| Route In Use | arrival star : star |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| ASRS Report | 128222 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 60 flight time total : 7000 flight time type : 600 |
| ASRS Report | 127770 |
| Events | |
| Anomaly | altitude deviation : overshoot conflict : airborne less severe non adherence : clearance non adherence : required legal separation |
| Independent Detector | atc equipment other atc equipment : unspecified other controllera other flight crewa |
| Resolutory Action | none taken : detected after the fact |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 11000 vertical : 0 |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Air carrier X wbound through my sector at FL370 and light transport Y on fever 2 STAR to sdl, az. Light transport Y was issued a descent to FL390 and pilot asked if the descent was at his discretion. I told him affirmative, however to expect to cross fever intersection at 11,000 and 250K. The aircraft misunderstood my expect for a clearance and started his descent, resulting in a loss of separation. Supplemental information from acn 127770: air carrier X noticed an aircraft on descent through our altitude in front of us. The light transport was in a rapid rate of descent. ATC indicated the light transport was descending into scottsdale, az, and was cleared to descend from FL450 to 390, and to expect further descent.
Original NASA ASRS Text
Title: LTT Y ALT DEVIATION ALT OVERSHOT DESCENT THROUGH OCCUPIED ALT OF ACR X. LESS THAN STANDARD SEPARATION.
Narrative: ACR X WBOUND THROUGH MY SECTOR AT FL370 AND LTT Y ON FEVER 2 STAR TO SDL, AZ. LTT Y WAS ISSUED A DSCNT TO FL390 AND PLT ASKED IF THE DSCNT WAS AT HIS DISCRETION. I TOLD HIM AFFIRMATIVE, HOWEVER TO EXPECT TO CROSS FEVER INTXN AT 11,000 AND 250K. THE ACFT MISUNDERSTOOD MY EXPECT FOR A CLRNC AND STARTED HIS DSCNT, RESULTING IN A LOSS OF SEPARATION. SUPPLEMENTAL INFORMATION FROM ACN 127770: ACR X NOTICED AN ACFT ON DSCNT THROUGH OUR ALT IN FRONT OF US. THE LTT WAS IN A RAPID RATE OF DSCNT. ATC INDICATED THE LTT WAS DESCENDING INTO SCOTTSDALE, AZ, AND WAS CLRED TO DSND FROM FL450 TO 390, AND TO EXPECT FURTHER DSCNT.
Data retrieved from NASA's ASRS site as of August 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.