European states will decide next year whether to impose 8.33kHz radio channel spacing in lower airspace, having set a date to bring down the upper airspace altitude threshold for such spacing to flight level 195 (19,500ft). Thirty states currently enforce the carriage of 8.33kHz radios, which relieves the congested air/ground frequency spectrum by enabling the creation of additional voice-communication channels not accessible with regular 25kHz-spaced radios. The present altitude threshold for 8.33kHz spacing is FL245 but this will be lowered to FL195 from 15 March 2007 under a recommendation from Eurocontrol’s decision-making authority. Lowering the threshold will probably bring additional types of aircraft, particularly turboprops, into the enforced-carriage zone.

Source: Flight International