Within the next 12 months, the USA will certificate the use of integrated area navigation systems (RNAV) as a normal means of en-route and terminal precision navigation, including final approaches.

The US Federal Aviation Administration has officially unveiled the plan, and will now need to devise and publish the required navigation performance (RNP) criteria. Although it intends to meet the one-year deadline, the FAA has not specified an actual date for the new RNP to go live.

Freeing aircraft from enforced reliance on ground-based navigation aids, the FAA says, confers benefits ranging from more direct routeing in both the upper and terminal airspace, to improved safety during descent toward those airfields where, at present, non-precision instrument approaches are the pilots' only choice. The FAA also points out the benefits of training pilots for only one type of instrument approach instead of many.

The new RNP will define the accuracy requirements to fly in certain airspace. The FAA says: "While [the RNP] does not specify that an operator carry a specific type of navigation equipment, it does require an automation capability aboard an aircraft to fly a specific flight procedure, such as an instrument approach into a particular airport. RNP is possible thanks to increasingly sophisticated levels of automation for positioning and navigation aboard an aircraft."

This is a reference to digital flight management systems (FMS) that can fly the aircraft accurately on preset flight trajectories, using either terrestrial navigation guidance, global navigation satellite systems, the aircraft's own inertial navigation system, or a combination. The agency says around 40% of US carriers' aircraft are fitted with RNP-capable FMS, and the rest could upgrade from the lower levels of RNAV that they are equipped to fly.

The FAA says it is "working with foreign civil aviation authorities to harmonise policies and standards so that RNP can become the global common denominator for air navigation". Eurocontrol says it is evaluating RNP as a means of improving airspace capacity.

Source: Flight International