I believe the 250 Kt. speed restriction was initially introduced in the United States following a fatal collision between a United Airlines DC-8 and a TWA Lockheed Constellation in The New York terminal area, This happened in December 1960, it's use has spread to most countries and is incorporated into The ICAO airspace requirements, certain countries( like Australia) will often give pilots a waiver on this requirement when requested , normally with minimal traffic around.....nothing like a B727 @ 350kts. to 20 nm.!!
Last edited by zlin77; 9th November 2009 at 04:29.