The highly anticipated NextGen area navigation, a type of RNAV equipment is now available at At Dallas / Fort Worth International Airport (DFW). It has been very successful, allowing the airport to accommodate practically a tripling in departures. In fact, NextGen satellite procedures allow for a 15-20% increase in departures per hour in congested periods.
What is RNAV?
RNAV is area navigation, which allows IFR aircraft to choose any route between a network of navigational beacons for route finding. Rather than flying from beacon to beacon, aircraft can fly any route within the coverage of station-referenced navigation signals. This allows lots of flexibility since aircraft can fly a straight course rather than zigzagging to and from beacons. The beacons are satellite serviced.
RNAV was introduced in the 1960’s and slowly waned in popularity as airlines began to favour inertial navigation systems rather than ground based navigation aids. RNAV was re-introduced after the massive introduction of satellite navigation. The procedure uses a combination of onboard equipment and satellites to ensure that aircraft follow a precise path and heading. Conventional RNAV procedures begin only once the aircraft is airborne, while ground based RNAV, such as the one at DFW, begins on the runway.
How does NextGen work?
NextGen starts working on the ground and only requires one nautical mile between departing aircraft. This system begins service on the runway and is provided to the aircraft as it enters high altitude airspace.
Conventional departure procedures, which require more correspondence between the pilots and ATC, call for separation minimums with departing aircraft of 3 nautical miles between take-offs. Those two miles make a difference. American Airlines, who is responsible for 80 per cent of DFW departures, has already reported an increase in throughput of between 10 – 20%.
Most aircraft use RNAV when they are in the air, however the difference at DFW is that RNAV navigation starts on the runway – on the ground, and not in the air. Hence separation is provided before takeoff allows smaller separation minimums to be observed.
In a congested airport like DFW, this really does make a difference. Less aircraft idling and waiting means fuel savings. Approximately 95% of the commercial jet fleet at DFW is equipped to fly RNAV. DFW is one busy airport – as you can see in the image above. In fact, it is number four in the world for aircraft movements, tallying 650,124 movements in 2012.
What are the benefits?
RNAV allows to conserve flight distance, save fuel, reduce congestion as well as allow flights into airports without beacons. RNAV beginning on the runway offers more time and fuel savings, for example, American Airlines has reported an annual fuel savings of around $10-12 million at DFW due to these improved RNAV technology. This will also improve local air quality.
Reduces possibility of verbal communication error
Since RNAV provides a pre-determined flight track programmed in the aircraft’s flight management system, this means less communication with pilots and ground controllers. This is more expeditious than the regular procedure, in which the controller gives the pilot a heading and the pilot will acknowledge it verbally. This gives less chance for a miscommunication to happen, and the FAA reports it has already decreased pilot-controller verbal correspondence by over one third. This gives controllers more time to concentrate on traffic that requires more complicated instructions.
This is a very popular technology that will likely be introduced at many congested airports worldwide.