The FAA issued an Airworthiness Directive (AD), warning Boeing 787 Dreamliner pilots not to use abrupt control inputs in case of erroneous airspeed indications.
The FAA states it has received three reports of in-service displayed airspeed anomalies on Boeing 787 Dreamliner airplanes. While further investigation is ongoing, the anomalous behavior is consistent with significant water ingestion or simultaneous icing of two or three of the three pitot probes. During each of the reported events, the displayed airspeed rapidly dropped significantly below the actual airplane airspeed. In normal operations, the air data reference system supplies the same airspeed to both the captain and first officer primary flight displays. During one in-service event, with autopilot engaged, the pilot overrode the engaged autopilot in response to the displayed erroneous low airspeed and made significant nose-down manual control inputs. In this situation, there is the potential for large pilot control inputs at high actual airspeed, which could cause the airplane to exceed its structural capability.
The AD, for all Boeing 787-8 and 787-9 airplanes, calls for a revision of the airplane flight manual (AFM) to instruct the flightcrew to avoid abrupt flight control inputs in response to sudden drops in airspeed, and to reinforce the need to disconnect the autopilot before making any manual flight control inputs.