FAA Warns Airlines Operating Boeing 787 About ILS Issue

The Federal Aviation Authority (FAA), has issued a Special Airworthiness Information Bulletin for owners and operators of Boeing’s Dreamliner.

The bulletin applies to the three Dreamliner models, the 787-8, 787-9, and 787-10. In their bulletin, the FAA flags the possibility of the autopilot flight director system failing to capture the localizer on an ILS approach.

FAA said there were reports that; “the autopilot flight director system was not providing proper guidance to capture the localizer when intercepting the localizer at large angles (40 degrees or more) from the runway and beam centerline.”

Several incidents have occurred, involving 787s flying approaches to Hong Kong from the east. The system guidance partially reduced the intercept angle to the localiser, with the aircraft initially turning towards the localiser heading but then stopping short and flying a constant heading.

This resulted in the aircraft intercepting the runway axis at an angle of 20-30°, says the FAA.

According to the bulletin issued by the FAA last week Thursday, it gave details of a forensic breakdown of the problem with Dreamliner ILS. According to the FAA, guidance from the autopilot flight director system partially reduced the intercept angle. However, the aircraft continued through the localizer at a heading not aligned with the runway centerline. The primary flight display continued to display “LOC” as the active roll mode, and there was no indication of a failure to capture.

The FAA says localizer and glideslope modes were engaged, and the AFDS provided guidance to descend on the glideslope. This meant the aircraft continued to deviate from the runway centerline and descend on an incorrect heading.

Over 1,000 Dreamliners are in service around the world. The agile plane has proved a big hit with airlines and is now flown by scores of operators. But the Dreamliner has not been without its problems.

FAA bulletin adds to a list of ongoing issues continuing to niggle at the otherwise successful plane.

In response to the incidents and the subsequent FAA bulletin, Boeing has issued a new Flight Crew Operations Manual Bulletin. The Boeing bulletin flags the problem and provides information on the operating instructions for AFDS operation during an ILS approach. The FAA also advised yesterday that Boeing is still working on updating the software to fix the problematic localizer mode behavior during Dreamliner ILS approaches.

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