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A B747-400 flight crew initiated descent early on approach to wsss. Fatigue was cited as a primary factor.
| Attributes | |
| ACN | 836393 |
| Time | |
| Date | 200905 |
| Local Time Of Day | 0001-0600 |
| Place | |
| Locale Reference | WSSS.Airport |
| State Reference | FO |
| Environment | |
| Flight Conditions | VMC |
| Aircraft 1 | |
| Make Model Name | B747-400 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Descent |
| Route In Use | Vectors |
| Flight Plan | IFR |
| Person 1 | |
| Function | Captain Pilot Not Flying |
| Experience | Flight Crew Last 90 Days 240 Flight Crew Total 22500 Flight Crew Type 3900 |
| Events | |
| Anomaly | Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance |
Narrative:
The ILS DME 02L approach has four charted fixes. Anuma is at 11.1 DME and the glideslope intercept altitude of 3500'. Akipo is at 7.8 DME with an altitude of 2500'; adnik is at 4.6 DME with an altitude of 1500'; and abvon is at 0.7 DME with no charted altitude. We were on radar vectors at an assigned altitude of 2;000' MSL on an assigned heading of 270 degrees; east of course between akipo and adnik. The autopilot was engaged in heading select and altitude hold. We were next given a heading of 350 degrees and cleared for the ILS 02C approach. The approach mode was armed. I set 1500' in the MCP; the crossing altitude at the next fix (adnik) on the localizer. A descent was begun to 1500'; as we intercepted the localizer outside of adnik; approach control asked if we had begun a descent. It was then that I realized that we should still be maintaining 2000' as we had not intercepted a published leg of the approach; nor had we been cleared to an altitude lower than 2000'. The approach and landing was made without further incident. Contributing factors to the premature descent (not excuses) include: greater than 18 hours of flight time in the last 48 hours; 13 hour time difference between home and singapore; flight left over 5 hours late; relaxed attitude with VMC conditions; with the runway; the city; and harbor clearly in view.
Original NASA ASRS Text
Title: A B747-400 flight crew initiated descent early on approach to WSSS. Fatigue was cited as a primary factor.
Narrative: The ILS DME 02L approach has four charted fixes. ANUMA is at 11.1 DME and the glideslope intercept altitude of 3500'. AKIPO is at 7.8 DME with an altitude of 2500'; ADNIK is at 4.6 DME with an altitude of 1500'; and ABVON is at 0.7 DME with no charted altitude. We were on radar vectors at an assigned altitude of 2;000' MSL on an assigned heading of 270 degrees; east of course between AKIPO and ADNIK. The autopilot was engaged in heading select and altitude hold. We were next given a heading of 350 degrees and cleared for the ILS 02C approach. The approach mode was armed. I set 1500' in the MCP; the crossing altitude at the next fix (ADNIK) on the localizer. A descent was begun to 1500'; as we intercepted the localizer outside of ADNIK; approach control asked if we had begun a descent. It was then that I realized that we should still be maintaining 2000' as we had not intercepted a published leg of the approach; nor had we been cleared to an altitude lower than 2000'. The approach and landing was made without further incident. Contributing factors to the premature descent (not excuses) include: greater than 18 hours of flight time in the last 48 hours; 13 hour time difference between home and Singapore; flight left over 5 hours late; relaxed attitude with VMC conditions; with the runway; the city; and harbor clearly in view.
Data retrieved from NASA's ASRS site as of April 2012 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.