Skip to comments.In-flight upset; Boeing 777-200, 9M-MRG
Posted on 04/19/2014 8:27:38 AM PDT by saywhatagain
At the same time, the aircrafts slip/skid indication deflected to the full right position on the Primary Flight Display (PFD). The PFD airspeed display then indicated that the aircraft was approaching the overspeed limit and the stall speed limit simultaneously. The aircraft pitched up and climbed to approximately FL410 and the indicated airspeed decreased from 270 kts to 158 kts. The stall warning and stick shaker devices also activated. The aircraft returned to Perth where an uneventful landing was completed.
For those who enjoy reading and thinking about strange happenings and coincidence.
However, no indication of loss of radio, transponder, etc etc
(Excerpt) Read more at atsb.gov.au ...
a Malaysian Airlines B777-200 (9M-MRG) was on a flight from Perth to Kuala Lumpur when it experienced a failure of its navigation system. The airplane suddenly climbed to FL410, then dropped 4000 feet, then climbed 2000 feet. The pilots flew the airplane manually back to Perth. Australian authorities investigated the incident. They determined that the failure was in the "operating software of the air data inertial reference unit (ADIRU), a device that supplies acceleration figures to the aircraft's flight computer." The device was manufactured by Honeywell and contained the fourth version of the operating system. A review of the software showed that the error did exist on the first three versions of the software, but had been suppressed by other features of the software. These other features were removed during the transition from the third version to the fourth version.
Why did the accelerometer fail?
The inertial unit itself did not fail, but there was apparently a bug in the software that interprets the raw data. This bug showed up when recent changes were made to the software.
And we thought software bugs in desktop PCs were bad!