Speed suddenly accelerates while cruising

I was flying B787-9 from RJTT to Helsinki. When I was around the Arctic Ocean region, the IAS suddenly increase dramatically from M.85 to over 1Mach. I was lucky that I caught this incident and exit game on time to avoid overspeed violation. What was more strange was that when I went back to replay to check what exactly happened, I found out the wind speed did not show at all in replay mode. Just wondering if anyone had encountered the same issue and how to avoid it. It was impossible to monitor the flight 24/7 especially in the long haul flight. Thank you!

Hi, This is a characteristic of replay mode, showing zero wind speed no matter what wind speed you encountered in flight.

But the effect of the encountered wind speed can still be seen in the replay by looking at the difference between IAS and GS.

Also, if you have AT set when the wind changes, you should see the AT behave consistent with that change in the difference between IAS and GS.

The first thing I naturally consider with your sudden jump in Mach is a rapid change in wind speed.

If you go back to your replay when that occurred, can you see the IAS and Mach jump suddenly while GS temporarily remains mostly unchanged (and did your AT cut to zero)?

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In the replay mode, the Mach number did not go up to Mach 1, it just went up to Mach.87 which would not pull the overspeed alarm for B787. Quite strange.

If a sudden wind speed change was the cause, Mach speed will jump immediately along with that sudden wind change, but it will come back down again from the AT self-adjusting. So, where you look on the timeline makes quite a difference.

Could you possibly share your replay?:

edit: btw, I just tested to re-confirm what I stated, but also to check that the Mach number jump was exactly the same while flying as shown in my replay and I did confirm that was true.

ive had this before, I was flying over the ocean at M.85 and suddenly jumped to .90 sounding the alarm, and this was after the update