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An air carrier A300 flight crew had the autoflt system change modes from localizer track to heading hold and they got off course while they were 'head down' entering data into the FMS.
| Attributes | |
| ACN | 387900 |
| Time | |
| Date | 199712 |
| Day | Wed |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : lax |
| State Reference | CA |
| Altitude | msl bound lower : 4000 msl bound upper : 4000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : lax |
| Operator | common carrier : air carrier |
| Make Model Name | A300 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | descent : approach descent other |
| Route In Use | arrival other arrival star : star |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 80 flight time total : 9000 flight time type : 600 |
| ASRS Report | 387900 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 110 flight time total : 7500 flight time type : 300 |
| ASRS Report | 388314 |
| Events | |
| Anomaly | non adherence : clearance non adherence : far non adherence : published procedure other spatial deviation |
| Independent Detector | other controllera |
| Resolutory Action | flight crew : returned to intended course or assigned course other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
During descent prior to handoff to lax tower, we were given 2 airspeed changes which affected our ability to meet altitude constraints on the approach. Sometime during the time it took to reprogram the FMS, the localizer track mode reverted to 'heading hold.' neither of us noticed this until approach control advised that we were drifting off course to the north of the runway 25L localizer. We made an immediate correction, and I am almost positive that no traffic conflict occurred. Neither of us knows how the localizer track mode was dropped, but we missed it because we were fixated on the vertical constraint change.
Original NASA ASRS Text
Title: AN ACR A300 FLC HAD THE AUTOFLT SYS CHANGE MODES FROM LOC TRACK TO HDG HOLD AND THEY GOT OFF COURSE WHILE THEY WERE 'HEAD DOWN' ENTERING DATA INTO THE FMS.
Narrative: DURING DSCNT PRIOR TO HDOF TO LAX TWR, WE WERE GIVEN 2 AIRSPD CHANGES WHICH AFFECTED OUR ABILITY TO MEET ALT CONSTRAINTS ON THE APCH. SOMETIME DURING THE TIME IT TOOK TO REPROGRAM THE FMS, THE LOC TRACK MODE REVERTED TO 'HDG HOLD.' NEITHER OF US NOTICED THIS UNTIL APCH CTL ADVISED THAT WE WERE DRIFTING OFF COURSE TO THE N OF THE RWY 25L LOC. WE MADE AN IMMEDIATE CORRECTION, AND I AM ALMOST POSITIVE THAT NO TFC CONFLICT OCCURRED. NEITHER OF US KNOWS HOW THE LOC TRACK MODE WAS DROPPED, BUT WE MISSED IT BECAUSE WE WERE FIXATED ON THE VERT CONSTRAINT CHANGE.
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.