B777-200
Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface; Situational Awareness
Aircraft Equipment Problem Critical; Deviation - Speed All Types; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued New Clearance; Aircraft Equipment Problem Dissipated; Flight Crew Diverted; Flight Crew Landed As Precaution; General Declared Emergency
Aircraft; Human Factors; Weather
During climbout experienced loss of reliable airspeed; loss of vertical guidance; loss of autothrottles; loss of autopilot while in heavy turbulence and at times extreme rain. Climbing through approximately FL240; after transiting an area of heavy rain lost vertical guidance bar of flight director. Shortly after that airspeed degraded rapidly. Disconnected autopilot and initiated a slight descent to recover airspeed. During straight and level flight experienced momentary airframe buffet. Relief Pilot supplied us with normal power setting and an attitude for an unreliable airspeed. First Officer got ground speed read outs from Center. I attempted reengaging the autopilot with no success. We obtained a block altitude from Center. Declared an emergency and decided to divert due to airframe buffet concerns. Some minutes after exiting rain conditions; systems gradually returned to normal. Executed a normal approach and landing. Aircraft had been loaded during heavy rain. During the last portion of loading; secondary ground power cycled on and off rapidly before dropping off. Experienced timing out of several systems immediately after; before they eventually came back. Loss of multiple systems. Dry loading.
B777 Captain experiences loss of reliable airspeed; loss of vertical guidance; loss of autothrottles and loss of autopilot while in heavy turbulence and at times extreme rain. Possible overspeed occurs and the crew elects to divert to a suitable airport. A few minutes after exiting the rain all systems gradually return to normal.