Julian Moxon/BRUSSELS

The introduction of area navigation (RNAV) and the flexible use of airspace in Europe, planned for March 1998, is being threatened by the failure of some airlines to acquire the required avionics, says Eurocontrol.

The Brussels-based air-traffic control (ATC) agency is increasingly concerned that operators without RNAV avionics may force a delay in the introduction of flexible airspace, seen as a vital step towards relieving airway "bottlenecks" in Europe and making off-airway airspace available.

Eurocontrol's airspace division chief, Alex Hendriks, says that around 20% of European airspace users are not appropriately equipped, and that engine hushkits enabling old-aircraft compliance with Stage 3 noise rules by low-cost start-up carriers and others will perpetuate the problem.

Hendriks notes that such airlines are reluctant to invest in upgraded avionics, "-because they see little added value in it". RNAV certification procedures in some countries are also failing to keep pace, he says, and avionics manufacturers are proving slow to respond to the requirement. He warns that ATC may become "unstable" if more than 5% of aircraft lack RNAV.

The flexible airspace concept allocates airspace temporarily to civil and military users according to their requirements. Aircraft no longer have to follow airways defined by on-track VHF (VOR) and non-directional (NDB) navigation beacons, but can fly direct using fixes from ground-based navigation beacons, inertial or satellite-based navigation systems.

Eurocontrol has recently reminded non-RNAV-equipped airlines that they must comply with the rule, agreed by European transport ministers in 1990. "From 1999, the system will be based exclusively on RNAV," Hendriks warns, and the date "-will remain firm". He says that while exemptions "-may be possible individually, across-the-board exemptions are out of the question."

Generally, aircraft without RNAV will be banned from the airspace. Eurocontrol admits that there has been "confusion" about the original requirement, which envisaged the introduction of precision RNAV in designated areas only for en route operations, and basic RNAV throughout the system. This was amended to require basic RNAV capability only.

Source: Flight International