An FAA Special Airworthiness Information Bulletin issued on September 24 (SAIB AIR-20-15) perfectly captures the conundrum that faces pilots flying modern aircraft. Automation can easily dupe a pilot into letting the airplane decide which way to go instead of the pilot ensuring that the airplane is doing what the pilot believed was specified.
The SAIB summarizes a problem with the avionics in the Boeing 787, where the autopilot flight director system (AFDS) fails to capture the localizer when the airplane intercepts the beam at angles greater than 40 degrees. Pilots are taught to verify the selected mode on the flight mode annunciator (FMA), after pushing the button on the flight guidance panel to select that mode. And in this case, the FMA showed exactly what the pilot expected—LOC—but the AFDS elected not to capture the localizer but continued beyond the beam at a 20- to 30-degree angle while also capturing and initiating a descent on the glideslope.
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