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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.
| Attributes | |
| ACN | 1194386 |
| Time | |
| Date | 201408 |
| Local Time Of Day | 0001-0600 |
| Place | |
| Locale Reference | ZZZZ.ARTCC |
| State Reference | FO |
| Environment | |
| Flight Conditions | IMC |
| Aircraft 1 | |
| Make Model Name | B777-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Climb |
| Component | |
| Aircraft Component | Airspeed Indicator |
| Person 1 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Deviation - Speed All Types Inflight Event / Encounter Weather / Turbulence |
Narrative:
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.
Original NASA ASRS Text
Title: 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.
Narrative: 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.
Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.