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An air carrier B757 crew had a track heading deviation when they failed to return the autoplt to LNAV after an aircraft equipment problem autoplt fault indication. Error admitted.
| Attributes | |
| ACN | 350262 |
| Time | |
| Date | 199610 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : pdz airport : sna |
| State Reference | CA |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : sna tracon : slc |
| Operator | common carrier : air carrier |
| Make Model Name | B757-200 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | cruise other 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 |
| ASRS Report | 350262 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| ASRS Report | 350050 |
| Events | |
| Anomaly | aircraft equipment problem : less severe non adherence : clearance non adherence : published procedure non adherence : far other spatial deviation |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course flight crew : became reoriented |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Aircraft was on autoplt flying the east side 1 arrival to sna. Autoplt and flight directors were cycled off and back on to clear an autoplt fault indication. After the fault was cleared and the autoplt re-engaged, LNAV was not selected and the aircraft continued in heading hold past the turn point at dawna for about 45 seconds before we noticed that we were not tracking the new course to archi. Heading select was used to turn left back to the arrival but, because of the shallow bank angle, the cross track error continued to increase to about 4 mi right of desired track before we got back on an intercept course to centerline. This could have been prevented if we had crosschecked LNAV sooner at the turn point. Also at this point we should have aggressively corrected back to the left with a 30 degree bank angle to minimize the distance off track.
Original NASA ASRS Text
Title: AN ACR B757 CREW HAD A TRACK HDG DEV WHEN THEY FAILED TO RETURN THE AUTOPLT TO LNAV AFTER AN ACFT EQUIP PROB AUTOPLT FAULT INDICATION. ERROR ADMITTED.
Narrative: ACFT WAS ON AUTOPLT FLYING THE EAST SIDE 1 ARR TO SNA. AUTOPLT AND FLT DIRECTORS WERE CYCLED OFF AND BACK ON TO CLR AN AUTOPLT FAULT INDICATION. AFTER THE FAULT WAS CLRED AND THE AUTOPLT RE-ENGAGED, LNAV WAS NOT SELECTED AND THE ACFT CONTINUED IN HDG HOLD PAST THE TURN POINT AT DAWNA FOR ABOUT 45 SECONDS BEFORE WE NOTICED THAT WE WERE NOT TRACKING THE NEW COURSE TO ARCHI. HDG SELECT WAS USED TO TURN L BACK TO THE ARR BUT, BECAUSE OF THE SHALLOW BANK ANGLE, THE CROSS TRACK ERROR CONTINUED TO INCREASE TO ABOUT 4 MI R OF DESIRED TRACK BEFORE WE GOT BACK ON AN INTERCEPT COURSE TO CTRLINE. THIS COULD HAVE BEEN PREVENTED IF WE HAD XCHKED LNAV SOONER AT THE TURN POINT. ALSO AT THIS POINT WE SHOULD HAVE AGGRESSIVELY CORRECTED BACK TO THE L WITH A 30 DEG BANK ANGLE TO MINIMIZE THE DISTANCE OFF TRACK.
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.