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Flight crew started to descend on an ILS approach before reaching the outer fix, causing approach controller to intervene to alert crew of their early descent.
| Attributes | |
| ACN | 498491 |
| Time | |
| Date | 200101 |
| Day | Tue |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : stl.airport |
| State Reference | MO |
| Altitude | msl bound lower : 4000 msl bound upper : 4500 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tower : pit.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B767-300 and 300 ER |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | ils localizer & glide slope : 30r other |
| Flight Phase | descent : intermediate altitude |
| Route In Use | approach : instrument precision |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 120 flight time total : 6000 flight time type : 800 |
| ASRS Report | 498491 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 40 flight time total : 16000 flight time type : 3000 |
| ASRS Report | 498022 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude non adherence : clearance non adherence : published procedure |
| Independent Detector | atc equipment other atc equipment : radar other controllera |
| Resolutory Action | controller : issued alert controller : issued new clearance flight crew : returned to assigned altitude |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
We were flying inbound on the runway 30R localizer. At an altitude of 4500 ft, the aircraft was level and stable. Clearance was received and acknowledged, 'cross tyrsh at 4500 ft, cleared for the ILS runway 30R.' 3500 ft was then set in the altitude window. We started discussing at what point we could fly the GS down to the runway. Not realizing I had not crossed tyrsh, I started a descent to 3500 ft below the GS. ATC told us we had to cross tyrsh at 4500 ft before descending. I immediately started to climb back to 4500 ft when ATC cleared us to just cross tyrsh at 4000 ft. The flight then continued without incident.
Original NASA ASRS Text
Title: FLC STARTED TO DSND ON AN ILS APCH BEFORE REACHING THE OUTER FIX, CAUSING APCH CTLR TO INTERVENE TO ALERT CREW OF THEIR EARLY DSCNT.
Narrative: WE WERE FLYING INBOUND ON THE RWY 30R LOC. AT AN ALT OF 4500 FT, THE ACFT WAS LEVEL AND STABLE. CLRNC WAS RECEIVED AND ACKNOWLEDGED, 'CROSS TYRSH AT 4500 FT, CLRED FOR THE ILS RWY 30R.' 3500 FT WAS THEN SET IN THE ALT WINDOW. WE STARTED DISCUSSING AT WHAT POINT WE COULD FLY THE GS DOWN TO THE RWY. NOT REALIZING I HAD NOT CROSSED TYRSH, I STARTED A DSCNT TO 3500 FT BELOW THE GS. ATC TOLD US WE HAD TO CROSS TYRSH AT 4500 FT BEFORE DSNDING. I IMMEDIATELY STARTED TO CLB BACK TO 4500 FT WHEN ATC CLRED US TO JUST CROSS TYRSH AT 4000 FT. THE FLT THEN CONTINUED WITHOUT INCIDENT.
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.