On Thursday, October 5, 2017 at 10:12:39 PM UTC+3, wrote:
The 250 limit is "indicated air speed" not true air speed. The airliner was probably doing ~300 knots at the time of the encounter.

Well that's weird, because a B737 or A320 or whatever cruising at Mach 0.78 at 35000 ft only has an IAS/EAS of 250 knots *anyway*, even though the TAS is 450.

So unless they go faster on descent the 250 limit is pretty much meaningless.