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A B767 flight crew departed 10;000 MSL prior to crossing krain when flying the ILS 25L to lax. They believed the use of FMS and the altitude alert setting for each crossing restriction--as opposed to setting the final altitude in the 'descent ladder' in the altitude alert and allowing VNAV to navigate the intermediate crossings--was a contributing factor.
| Attributes | |
| ACN | 1028464 |
| Time | |
| Date | 201208 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | LAX.Airport |
| State Reference | CA |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B767-300 and 300 ER |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Initial Approach |
| Route In Use | STAR SEAVU |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | FMS/FMC |
| Person 1 | |
| Function | First Officer Pilot Flying |
| Qualification | Flight Crew Flight Engineer Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine |
| Experience | Flight Crew Last 90 Days 60 Flight Crew Total 7200 Flight Crew Type 3800 |
| Person 2 | |
| Function | Pilot Not Flying Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 80 Flight Crew Total 9000 Flight Crew Type 6000 |
| Events | |
| Anomaly | Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy |
Narrative:
[We were] descending in accordance with seavu.SEAVU2 STAR. At the transition to ILS 25L procedure at lax; we began a descent from 10;000 ft at luvyn intersection instead of maintaining 10;000 ft until krain intersection and then a descent to 9;000 ft on the ILS procedure at taroc intersection. I was the flying pilot and elected to use flight level change at luvyn instead of VNAV due to sluggish response from the VNAV system and changes to assigned speed. ATC mentioned at krain that we needed to be at 10;000 ft even though we descended to approximately 9;700 ft before catching our mistake and climbing back up to 10;000 ft. [We had] no further incidents after this point; uneventful landing.our company procedure is to fly the STAR and approach in VNAV and set each altitude on the step downs and reselect VNAV until reaching the final approach fix. It is labor intensive and errors can occur when ATC issues changes to crossing altitudes and adjusts speeds (VNAV has a hard time re-computing). I think errors would be reduced if the company procedure was changed so that VNAV was used but the final approach altitude (or ATC limit) was set and allow VNAV to step down in accordance with the FMC computed rates instead of continually re-selecting VNAV every time the step down altitude is captured. This would allow both pilots more time to monitor traffic; deal with ATC changes; as well as procedural compliance.
Original NASA ASRS Text
Title: A B767 flight crew departed 10;000 MSL prior to crossing KRAIN when flying the ILS 25L to LAX. They believed the use of FMS and the Altitude Alert setting for each crossing restriction--as opposed to setting the final altitude in the 'descent ladder' in the altitude alert and allowing VNAV to navigate the intermediate crossings--was a contributing factor.
Narrative: [We were] descending in accordance with SEAVU.SEAVU2 STAR. At the transition to ILS 25L procedure at LAX; we began a descent from 10;000 FT at LUVYN Intersection instead of maintaining 10;000 FT until KRAIN Intersection and then a descent to 9;000 FT on the ILS procedure at TAROC Intersection. I was the flying pilot and elected to use flight level change at LUVYN instead of VNAV due to sluggish response from the VNAV system and changes to assigned speed. ATC mentioned at KRAIN that we needed to be at 10;000 FT even though we descended to approximately 9;700 FT before catching our mistake and climbing back up to 10;000 FT. [We had] no further incidents after this point; uneventful landing.Our company procedure is to fly the STAR and Approach in VNAV and set each altitude on the step downs and reselect VNAV until reaching the Final Approach Fix. It is labor intensive and errors can occur when ATC issues changes to crossing altitudes and adjusts speeds (VNAV has a hard time re-computing). I think errors would be reduced if the company procedure was changed so that VNAV was used but the Final Approach Altitude (or ATC limit) was set and allow VNAV to step down in accordance with the FMC computed rates instead of continually re-selecting VNAV every time the step down altitude is captured. This would allow both pilots more time to monitor traffic; deal with ATC changes; as well as procedural compliance.
Data retrieved from NASA's ASRS site as of July 2013 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.