New Tricks

As modern aircraft designs employ new materials, engine technology and aerofoils as means of squeezing even more from their state of the art hardware, there is also an ongoing struggle to find safer, more efficient ways of air travel by better utilising the airspace through which they pass. From soaring fuel costs to environmental concerns, aviation is continually being challenged on its road to a sustainable future.

One such player in this ongoing game in the skies overhead is Automatic Dependent Surveillance Broadcast technology, known as ADS-B. Australia can count itself as a pioneer of the technology and is the first nation to possess virtually national coverage, albeit above FL300, and relatively extensive coverage down to even 10,000 feet. While the first Australian airliner was continually tracked by ADS-B five years ago, in essence, the system is the descendant of traditional radar technology which harks back to World War Two. However, unlike its grandparent, ADS-B does not rely on bouncing back a ground emitted pulse to a radar station as the ADS-B signal originates from the aircraft. Drawing information from other aircraft systems such as GPS, ADS-B airborne avionics broadcast identification, position, altitude, velocity vector, vertical rate and other information about twice a second on a digital data link.

By virtue of this, ADS-B’s applications are not limited to communication with the ground station; it also enables air-to-air transfer of information for pilots to enhance their situational awareness of proximate traffic. For air traffic control, ADS-B provides more accurate information, more frequently in a radar-like display for areas where there was previously no radar coverage.

Such benefits are provided by a series of ground stations which incur a fraction of the cost of traditional radar installations and their necessary supporting infrastructure. It was to this backdrop of enhanced safety to provider and user alike that in February 2009, CASA announced that the fitment and operation of approved ADS-B avionics equipment mandatory on, and from, 12 December 2013 for all Australian aircraft operations at, or above, FL 290 (unless CASA has authorised otherwise). For airlines and their fleets in the stratosphere the line had been drawn in the sand; equip your aircraft with ADS-B or be confined to fuel-guzzling flight below 29,000 feet.

New Horizons.

The expense of retrofitting an extensive system to a fleet of aeroplanes is not a decision that is made lightly and in the case of the QANTAS Boeing 767 program this figure is in the vicinity of $15 million. Many issues are considered ranging from the capital outlay with a view to the remaining service life of the aeroplane as opposed to the cost of continuing to operate the aircraft inefficiently below FL290.

Operating at lower levels is a major issue for jet aircraft, for it is with altitude that real savings can be made through reduced fuel flows. Typically at mid-weights and a cost index of forty, a 767 burns around 4,700 kg/hr at 39,000 feet, which is around 200kg/hr less than at 28,000 feet It may not sound like a huge number, but multiply it by eight hours flying per day at the current fuel price for the 16 aircraft receiving the upgrade and the annual amount starts to register significantly on the balance sheet. Flight at FL290 and below also potentially places more weather in the aircraft’s path calling for an increased number of enroute diversions, more track miles and consequently even more fuel is burnt. Furthermore, the increased level of emissions in the lower flight levels is not the best news for the environment.

Aside from the obvious deterrent of increased fuel flows and dodging weather, there are a number of tangible benefits that stem from the ADS-B upgrade, many of which are associated with the equipping of the aircraft with GPS. Through this enhanced level of accuracy, more precise enroute and terminal navigation equates to reduced flight times and fuel burn. The ability to take advantage of the Australian Organised Route Structure (AUSOTS) by using flex tracks and finding favourable winds further improves enroute efficiency.

By virtue of the ADS-B program, some of the new equipment involved will also make available to the 767, the new generation of Approaches with Vertical Guidance (APV), including RNP-AR procedures. These approaches also add an increased level of efficiency in terms of fuel and time, but additionally offer a greater degree of schedule integrity by virtue of lower minimas at certain airports and when traditional ground-based approach aids are undergoing maintenance and the weather is less than ideal. Such was the case recently at Cairns when the Boeing 737-800 fleet was able to fly the RNP procedures to a lower weather minimum when the ILS was unserviceable.

Taking the 767 and equipping the aircraft with the new technology permits both the life and the capability of the aeroplane to be extended. Yet before those rewards can be reaped, there is a deal of work to be done to ready each aeroplane for the era of ADS-B.

The Upgrading Business.

The success, benefits and coverage of ADS-B in the upper flight levels virtually assured that its carriage would become mandatory for airliners at some point. In fact, most new airliners delivered to Australia in recent times have been arriving with ADS-B capability fitted and successfully operating within the system. For QANTAS, the first aircraft so equipped was the Airbus A330-300 VH-QPC which arrived in January 2004, even though the ADS-B airspace system was not yet in place. Subsequent to VH-QPC, all new deliveries of B737-800, A330 and A380 have been ADS-B equipped while the B747-400 fleet was retrofitted from 2006 to comply with mandatory requirements in European airspace. The missing piece in the puzzle was the Boeing 767.

Part of the reason for this would appear to be that without a date set for compliance, it was difficult to determine whether equipping the 767 with ADS-B would ultimately be necessary. With December 2013 subsequently set as the date, a fleet decision could now be made upon facts rather than speculation and the outcome was that, like the B747-400, the QANTAS Boeing 767’s would be retrofitted with ADS-B technology.

Such an engineering project is not simply a case of plugging a dash-mounted GPS into a cigarette lighter. It involves the modification, replacement and addition of numerous components onto an operational fleet of sixteen aircraft where downtime equates to significant cost. Consequently, much of the modification work is scheduled to take place in conjunction with regular scheduled maintenance ‘C Checks’. Simulators will also require a degree of modification and engineers and pilots must receive training, while the actual installation must all be completed to CASA’s satisfaction and in line with Boeing’s certification standards.

From an engineering perspective, the first step in the process is to upgrade the flight management system to the Honeywell ‘Pegasus’ 2009 FMS, a system that three of the 767s already possessed and a further three have subsequently received. Each aircraft will also have three ‘Multi-Mode Receivers (MMR) installed which are being re-directed from the B737-800 fleet as they are progressively upgraded for GLS capability. MMRs are the high-integrity, multi-function navigation units that in conjunction with the GPS antennas on top of the fuselage enable GPS reception. The system then only requires a software upgrade to make the aeroplane RNP procedure capable. This first stage of the process is actually already taking place ahead of the scheduled ‘C checks’ and availing RNP capable aircraft subject to training.

The TCAS system is being modified while the EGPWS system is being adapted to accept the GPS input from the MMRs. Additionally, the existing transponders are being replaced with units capable of broadcasting elementary, enhanced and extended transmissions of information referred to as ‘squitters’. This ability is at the very heart of ADS-B.

With the hardware in place, the QANTAS flight crews and engineers also require training in the operation and ongoing maintenance of the system. For the pilots, this will primarily relate to training in RNP approach procedures as the actual ADS-B function is a passive system not requiring any pilot input other than turning on the newly fitted transponders and ensuring that the flight plan reflects the carriage of the new system. Before this training can occur however, the simulators must be modified to reflect the new systems as they are fitted to the actual aeroplane. For the engineers, they are required to undergo CAR214 training. In the first instance, the heavy maintenance engineers need to do so for the initial embodiment of the system, while the line engineers subsequently learn how to support the aircraft in service. When both man and machine are certified as competent, the QANTAS 767s will be able to operate utilising the full extent of the benefits on offer from ADS-B and RNP operations.

New Tricks.

As an airline category aeroplane, the Boeing 767 has proven itself to be a classic over a diverse service life. It has filled many varied roles for many varied operators, both civilian and military, passenger and freight. Now the QANTAS 767 fleet is gaining a new lease of life in the rapidly evolving world of ADS-B and precision navigation.

Re-equipped and re-vamped, the wide body airliner is set to continue its life free of the restrictions that the new age may impose on others. To the contrary, the Boeing 767 is set to navigate the airways with a higher degree of precision than it has ever known and fly approaches more efficiently than it could previously have been imagined. In an era of ever-changing technology, the 767 is set to show the aviation world that this classic aeroplane still has a trick up its sleeve.