Indonesian media quoting unrectified(?) autothrottle problem in the accident aircraft...
A Tempo source who is aware of the problem said that the SJ-182 aircraft autothrottle system has experienced recurring problems. "The autothrottle has been repetitive for a month," he told Koran Tempo. Regarding the SJ-182 autothrottle, sources said the system had experienced problems since December 2020 or when the plane returned to flight after being grounded for nine months. Soerjanto explained, if the system had problems, it should have been anticipated by manual regulation. "No problem, just use your hands like the old days," he said.
https://today.line.me/id/v2/article/op96ep
Asymmetric thrust due to autothrottle problem has led to fatal accident in B737 before (but, in a different phase of flight).
In my previous post 79, when observing the lower performance, specifically the slower speeds from about 4000 feet on up, a speculative thought was that of a pitot/static system malfunction.
However, a new speculative thought occurs. If the autothrottle was engaged and one engine gently rolled back to, or near to flight idle with the autothrottle active and the other engine maintained climb thrust...the performance...specifically the rate of climb and/or the speed would be reduced from normal. The secondary flight control effects of the thrust asymmetry would be masked by the autopilot.
If IAS continued to decreased, the aileron control would offset ("cross") until the flight path eventually deviated laterally due to untrimmed rudder.
And then if the autopilot was then disconnected with the controls all crossed, the sudden out of trim forces would be unexpected and cause a rapid roll...
Total speculation of course...
The transport minister said on Saturday that the jet appeared to deviate from its intended course just before it disappeared from radar, AFP reports.
“The aircraft’s final moments are … very concerning as the speed that (it) was flying at that altitude was much lower than expected,” said Stephen Wright, professor of aircraft systems at Finland’s Tampere University.
https://www.dailytelegraph.com.au/ne...ct/news-story/