BOAC-From an ATC point of view it amazes me how the same aircraft type flown by the same company on the same route will fly at sometimes VERY different speeds. If I need you on a speed for sequencing I'll tell you,if you are given "speed at your discretion" then it is your call,as fast or as slow as you like.I would add however that if you are going to fly at a speed that is particularly slow for your aircraft type during the descent,then let me know if you can. I would "expect" a B737 to descend at 280-310ish knots. I have been caught out before because 737s/A320s etc have hit the brakes and have slowed to 250 or below very early in the descent.My fault really because as Del Prado says,no speed control means exactly that.
To answer your question,apart from adhering to the SLP's then there is no standard IAS.But if you want to fly slowly,gimme a shout
Cheers,rolaaand.