The road to future communications, navigation and surveillance operations will not include any major technology upheavals in user requirements before 2020, according to projected roadmaps presented at ICAO’s Air Navigation Conference in Montreal recently. In fact, new technologies mentioned for each of the three regimes were usually described in terms of their potential future benefits, with no suggestion of their actual readiness for implementation. There was just one proposed mandate (by Russia, for Glonass GNSS equipage in Russian-registered aircraft) and one Eurocontrol mention of a possibly desirable mandate for broader use of current advanced FMS in future performance-based terminal procedures.

In the communications segment, the major challenge is capacity, as always. Datalink and protocols under development for the Internet, but with appropriate high security safeguards, could offer significant amelioration in the future. In navigation, GNSS is clearly established as aviation’s standard for many years to come, with four ICAO-compatible globe-girdling systems–from the U.S., Russia, Europe and China–expected to be fully operational by 2020, plus two equivalent regional systems (from India and Japan) by the same date.

There was, however, concern about accidental and deliberate jamming and spoofing attacks on GNSS, which will be only partly mitigated by the steadily increasing numbers of the GNSS constellations’ satellites–expected to approach 150 in ten years. Consequently, the conference endorsed the need for onboard GNSS backup facilities: specifically, inertial systems and scanning DME, supported by “thin” terrestrial DME networks.

Continuing even basic VOR networks was not mentioned, although it should be noted that the meeting’s prime focus was “upper end” avionics installations, which would include much of corporate aviation. ILS Cat II and III will continue for an unspecified period (dependent on GNSS augmentation plans) but with ILS Cat III remaining in any event as a backup approach service. Cat I approach service is expected be provided by Waas/SBAS, but the nature of Cat I backup in the event of a GNSS failure is still being assessed. Future surveillance service is seen as being a mix of ADS-B, multilateration and a steadily shrinking secondary-radar network, with TCAS slated for eventual replacement by the next-generation ACAS.

Performance-based Navigation Needed

Above all, the major advance in airborne capabilities would be in performance-based navigation (PBN), which is anticipated to be basic to all civil aircraft, from the simplest Rnav applications to advanced RNP procedures. Discussions at the conference suggested attendees regarded flight without dependence on some form of PBN guidance as almost an emergency condition. In fact, some national representatives and airline speakers attributed the continuing problem in achieving previously flight-planned optimum departure and arrival paths in high- and medium-density airspace to the lack of PBN capabilities in many aircraft today.

An Emirates Airline presentation at an ICAO PBN Symposium shortly before ICAO’s Air Navigation Conference illustrates the challenge for air traffic management to handle aircraft of mixed capabilities.

The graph shows, in purple, the vertical profile of the idle-power continuous descent that was flight planned for one of the airline’s A340s on its return to Dubai. The graph’s left-hand vertical axis shows, in blue, the aircraft’s pressure altitude in feet, while its horizontal axis shows the flight’s accumulated track miles. The right-hand vertical axis in green is the critical one, showing vertical speed, in feet per minute, which essentially equates to power settings during the descent.

The flight-planned idle-power descent would have put the aircraft in a landing configuration at around 3,470 miles flown. But due to conflicts during descent, it was forced to fly an additional 140 miles, much of it below 16,000 feet and with several power changes, resulting in an extra 2.1 tonnes of fuel burn.

Clearly, this example is not simply the result of having PBN- and non-PBN-equipped aircraft operating in the same airspace. Nevertheless, there was a strong consensus among airline and ATC attendees at the ICAO PBN Symposium and its follow-on Air Navigation Conference that the time is drawing near for the introduction of concepts such as “best equipped, best served.”