B767 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 150; Flight Crew Total 31500; Flight Crew Type 2000
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Flight Deck / Cabin / Aircraft Event Passenger Electronic Device
Flight Crew Overcame Equipment Problem; General Maintenance Action
Human Factors; Aircraft
Approximately 3 miles outside final approach fix; aircraft descending in FLCH to 2000 MSL; passing 3300-3200 MSL aircraft had LOC engaged and captured; aircraft started a 10-15 degree bank right away from the LOC course. Both pilots verbalized the deviation and as the PFD showed a LOC flag I disconnected the autopilot and transitioned to the standby ADIs which displayed normal course path displays and considered a missed approach nearing 2100 MSL when the First Officer confirmed visual sighting of the runway. I confirmed visual with standby ADI guidance; continued the approach manually meeting the 1000 and 500 foot stabilized approach criteria to an uneventful landing. No airport surface traffic was present to affect the LOC signal and arrival congestion prevented further discussion with the tower. I questioned the purser and he stated many people were on their cellphones even after making multiple announcements. This incident was identical to one I had years ago in a 737 on a simultaneous ILS landing IAH Runway 26L. Can't prove cellphones do this of course; and can't prove they do not. Heads Up Warning.
On final apch to 15 (ILS Z) with the autopilot on; descending thru the bottom of the overcast layer; the acft started drifting right of course and was no longer following the glide path (drifting high). The Captain (CA) promptly took over hand-flying the acft below the wx to a visual apch and uneventful landing. Although a little high and right; the CA's prompt; correct actions saved a go-around in proximity to significant terrain; in the dead of night; and with both of us tired. Post-flight query of the F/As evidenced that numerous pax were using their cell-phones just prior to landing (possible causal effect?)Prior to the dramatic; un-alerted; insidious error of the autopilot; it had worked flawlessly leading us to question if frequency meaconing could be the cause of its failure (it simply no longer received the ILS data)? Not sure of cause.
B767 flight crew reported deviating from ILS course and altitude on approach to SPIM because of an autopilot error; possibly caused by passenger cell phone use.