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Small transport descended below assigned altitude and had less than standard separation with bmb due to ambiguous clearance from approach controller.
| Attributes | |
| ACN | 194842 |
| Time | |
| Date | 199111 |
| Day | Sat |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : saw airport : mqt |
| State Reference | MI |
| Altitude | msl bound lower : 2800 msl bound upper : 3700 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : saw |
| Operator | common carrier : air carrier |
| Make Model Name | Small Transport, Low Wing, 2 Turboprop Eng |
| Flight Phase | cruise other |
| Route In Use | approach : straight in enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | other |
| Make Model Name | Military Transport |
| Flight Phase | cruise other |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : cfi pilot : commercial pilot : instrument |
| Experience | flight time last 90 days : 210 flight time total : 3200 flight time type : 1200 |
| ASRS Report | 194842 |
| 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 | other controllera |
| Resolutory Action | none taken : anomaly accepted |
| Consequence | Other |
| Miss Distance | horizontal : 6000 vertical : 100 |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
While being vectored for mqt municipal localizer back course 26 approach, this clearance was given, 'maintain 3700 ft until established on the localizer, approach clearance to follow.' I intercepted the localizer within 10 mi of FAF and when established descended to 2800 ft as published. A few mi from FAF sawyer approach inquired as to our altitude, stated that we missed a bmb Y by 100 ft and 1 mi, and that he meant in the clearance that we maintain 3700 ft. He admitted that his clearance was vague and after discussing the incident, the captain and I decided we could have had the clearance clarified before descent.
Original NASA ASRS Text
Title: SMT DSNDED BELOW ASSIGNED ALT AND HAD LTSS WITH BMB DUE TO AMBIGUOUS CLRNC FROM APCH CTLR.
Narrative: WHILE BEING VECTORED FOR MQT MUNICIPAL LOC BACK COURSE 26 APCH, THIS CLRNC WAS GIVEN, 'MAINTAIN 3700 FT UNTIL ESTABLISHED ON THE LOC, APCH CLRNC TO FOLLOW.' I INTERCEPTED THE LOC WITHIN 10 MI OF FAF AND WHEN ESTABLISHED DSNDED TO 2800 FT AS PUBLISHED. A FEW MI FROM FAF SAWYER APCH INQUIRED AS TO OUR ALT, STATED THAT WE MISSED A BMB Y BY 100 FT AND 1 MI, AND THAT HE MEANT IN THE CLRNC THAT WE MAINTAIN 3700 FT. HE ADMITTED THAT HIS CLRNC WAS VAGUE AND AFTER DISCUSSING THE INCIDENT, THE CAPT AND I DECIDED WE COULD HAVE HAD THE CLRNC CLARIFIED BEFORE DSCNT.
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.