Overview
On 21 November 2014, a Boeing 787-800 (registration not specified) was conducting an approach to Warsaw Chopin Airport (EPWA) when the flight crew needed to change the type of approach and runway direction. The Flight Management Computer (FMC) refused to accept any modifications. No failure indications were annunciated. The crew had no means to override the FMC. The landing was completed on runway 33, which had been previously selected in the FMC. The crew was aware of a Boeing bulletin regarding FMC issues.
Incident Details
During descent for landing, the necessity arose to change both the approach type and the active runway. The FMC did not permit any changes to the flight plan or approach procedure. The pilots reported no control over the unresponsive FMC. The aircraft landed safely on runway 33 as originally programmed. Similar FMC problems had been recorded on 20 July 2014 (event 1130/14) and 23 August 2014 (event 1448/14) with the same aircraft type.
Investigation
The investigation was conducted by the operator under the supervision of the Polish State Commission on Aircraft Accident Investigation. Honeywell, the manufacturer of the B787's software, was able to reproduce the reported issue. The problem occurred only with Standard Terminal Arrival Routes (STARs) that contained exactly 14 waypoints, and only when attempting to select a different approach not contained within that STAR. A software modification called Flight Management Function Block Point 3 (FMF BP3) was proposed for the fourth quarter of 2015. Honeywell also explored other solutions, such as updating the navigation database. Boeing announced a new navigation database version containing a fix.
Corrective Actions
Since Boeing proposed a solution for the third quarter of 2015, the operator negotiated with the aircraft manufacturer to expedite the fix, without success. On 23 December 2015, Boeing issued Service Bulletin B787-81205-SB340013-00 Issue 01, followed by Revision 02 on 6 May 2016. These modifications to the Flight Management System (FMS), Thrust Management System (TMS), and Communication Management Function (CMF) – collectively known as Block Point 3 (BP3) – incorporated the necessary corrections. The operator informed the Commission of the implementation plans. The incident was recorded in the operator's Safety Management System (SMS) database and included in safety performance indicators. No safety recommendations were issued by the Commission.