How regular is the rumble?

[Scarbagjack]

Thanks for the replys, so I suppose I can take it that the speed brake applications,relating to higher/quicker type of descents, occur mostly in the US..or when other factors warrant their use.

I dont know much about flying aircraft, so please bear with my queries, but can an aircraft get away on the piolt in an agressive jetstream, as in excessive speed? If so, what actions will they take to bring the speed back..such as descending below, ( with ATC clearance), or out of the fast winds,throttling back, or spoiler activation.

I mean in the context that the aircraft is not ready for its planned descent at this stage.

Thanks again.