Flying a fine line

In this world, straight lines are bent in the pursuit of efficiency.

Second to safety, efficiency is paramount in modern commercial aviation.

As fuel prices remain painfully high and concern about the environment draws ever greater attention, time has very much become money. Big money. For aviation, the race to become leaner and greener is not limited to aircraft design, but how to best utilise existing fleets and those of the future.

Central to this theme is the development and management of the global airways systems, with Australia’s Airservices, responsible for managing 11 per cent of the world’s airspace, at the forefront in developing more efficient airspace usage practices, from flex tracks to user preferred routes (UPRs), even if implementation is slower than industry would have wished.

The pursuit of more efficient air routes equates to savings on many levels. The shorter flight times offered by optimal routes translate directly into reduced fuel burns and lower levels of emissions. More subtly, these reduced flight times equate to more revenue generating passengers carried between time-based aircraft overhauls.

In 2005 a 747-400 flying from San Francisco to Hong Kong would have had a fuel bill of around US$99,000. In 2008, the same bill could have been as high as US$168,000, an increase in the order of 70 per cent. Trials to date of UPRs have encouragingly shown significant potential savings in fuel burn and provide a major incentive for airlines to see these airways in effect.

Environmentally, aviation is also being called to account. Every tonne of fuel saved equates to over three tonnes fewer CO2 emissions released into the air. Better traffic management will also equate to more ‘continuous descent’ approaches with low or idle power settings in lieu of the ‘throttle up’ level segments required at times currently. That will mean a lower noise footprint in terminal areas as well as lower emissions.

The strategy

The Australian Air Traffic Management Strategic Plan grew from the need for Australia to be proactive in the development of airspace management.

Published by the Australian Strategic Air Traffic Management Group (ASTRA), it recognises the need for long term planning in a highly dynamic environment and endeavours to look to 2025 and beyond. Not an easy task given the ever changing nature of aviation technology, economics, development and community expectations.

With the first draft appearing in 1999 and subsequent publication occurring in 2001, ASTRA’s initiative was ground breaking. Over the ensuing years the playing field has continually changed with oil prices, environmental awareness and the increased consideration of security in the wake of 9/11, to name but a few challenges. To this end the plan saw a second edition in 2003 and has continued to be updated, most recently in 2007, in response to the ever changing needs of the industry and stakeholders.

One of the plan’s definitive goals is the provision of User Preferred Trajectories (UPTs). In its ultimate form, the management of a flight ‘trajectory’ takes onboard all considerations from flight inception to post flight analysis. Freed of fixed air routes, it takes the flight from gate to gate and beyond. It is no longer just a matter of picking the best level and route for winds; UPTs consider ground operations, the flight phase, and can even play a role as early as fleet purchases.

But this is an ultimate goal. On the way, the strategy wisely set out a series of stepping stones, from Tasman user preferred routes to international flex tracks; international user preferred routes; domestic user preferred routes; and finally user preferred trajectories.

The current focus is on the development of flex tracks and user preferredroutes. Even in these more basic forms, flex tracks and UPRs have made significant inroads into the efficiency of airspace.

Flex tracks

Traditionally, air routes have been highways in the skies along published tracks with defined reporting and turning points. Laid out on charts like a street directory for the skies, these routes were relatively rigid and divergence from them in controlled airspace could only occur with prior approval except in the case of emergency. By necessity, fixed air routes will exist for some time to come, but even so they are the target of improved efficiency and such anomalies as inefficient dog legs to track via ground based navigation aids are becoming straight lines with the aid of modern nav systems.

Flex tracks represent the first steps away from fixed air routes on the path to user preferred trajectories. A flex track is defined as “A non-fixed ATS route calculated on a daily basis to provide the most efficient operational flight conditions between specific city pairs”. It draws upon forecast weather and recent actual winds to provide air routes that are best suited to current conditions. These tracks are generated by a person designated as the ‘trackmaster’ and promulgated as provisional flex tracks subject to approval by selected airlines. When their suitability is confirmed, the flex tracks are published as Track Definition Messages and NOTAMs and forwarded to airlines for flightplan preparation.

Under the title of AUSOTS (Australian Organised Track Structure), Airservices trialled the concept internationally between Australia and South East Asian airports back in 2005. Prior to the trial, a pilot flight in 2004 had dramatically demonstrated the tangible benefits of flex tracks when it shaved 43 minutes and over eight tonnes of fuel burn off the fixed routes between Dubai and Sydney. Similarly, new international routes implemented in May 2007 boasted savings of between 200 and 2000kg per sector.

Peter Curren, Airservices’s manager, national ATC capability, highlighted some of the recent developments in AUSOTS at Airservices’s recent Waypoint presentation. These included new city-pairs that include Bangkok- Sydney, Brisbane-Perth-Sydney and Mumbai-Sydney. Additionally in some cases, the points at which flex tracks transition into fixed routes, or ‘gates’, have moved closer to the capital centres, allowing greater use of the flex track and reducing constraints. Similarly, work with regional air navigation service providers to gain new air routes through Indonesia, Colombo and Chennai airspace to facilitate greater access to commence flex tracks on reaching Australian airspace is underway.

Flex tracks first appeared in 1996 on trans Pacific routes and over time evolved into the more advanced form of traffic management, user preferred routes. Peter Curren acknowledged in his presentation that “…flex tracks aren’t UPRs, but until we get there, we’re determined to deliver on other fuel burn reduction initiatives. Flex tracks is one such initiative. ” Just as fixed air routes have been optimised and developed into flex tracks, in time, so shall UPRs rise from the current structure.

User Preferred Routes

User preferred routes take flex tracks a step further and move them towards the ultimate goal of user preferred trajectories.

Unlike flex tracks, UPRs are not only flown by the airspace user, they are generated by them. Notwithstanding the prevailing constraints such as conflicting traffic and airspace boundaries, UPRs seek to provide the optimum flightpath and offer even higher levels of savings and reduced environmental impact.

UPRs weigh up numerous operational factors including airspace, weather, prevailing winds, aircraft type and engine configuration. The airline then generates a flightplan to take best advantage of the prevailing conditions and submits it. The aircraft will then fly the planned route as cleared by ATC and undertake the same responsibilities relating to maintaining the track as if it were a fixed air route.

To date, aircraft have routinely employed UPRs on trans-Pacific routes between Australia’s eastern capitals and the US west coast. Limited UPRs also exist in both directions on the city pairs of Dubai-Perth and Auckland- Perth. On August 11, Japan Air Lines commenced UPR trials on its routes between Japan and Hawaii. With 4700 flights per annum over these routes, JAL sees a potential saving of 1. 93 million litres of fuel and almost A$2 million per year. The airline is also pursuing the use of UPRs on some routes to Australia.

As with any progress, it is not without growing pains. In some cases the hurdles stem from airspace issues as different Flight Information Regions (FIRs) have differing restrictions for aircraft filing UPR routes. For example, an aircraft wishing to fly from New Zealand to Japan will transit Auckland, Brisbane and Nadi FIRs, all of which support UPRs for FANS equipped aircraft. However, further en route, only part of Port Moresby’s airspace supports UPRs and Guam FIR requires planning via fixed ATS routes.

Traffic conflict and the means to address it is yet another area of concern.

With all manner of aircraft submitting plans along their preferred routes, ATS still needs to provide separation betweenthese aircraft. Added to the mix are the varying separation standards. From Airservices’s perspective, the flightplan conflict function software that is to underpin this critical function has not been able to be implemented on the desired schedule and consequently delayed the implementation of UPRs.

Without a satisfactory means to manage traffic conflict, the answer lies in increased physical separation standards. Laterally this would equate to additional track miles and vertically, lower levels would translate into higher fuel burns. Both options cancel out many of the benefits of UPRs, so resolving the traffic conflict issue is central to the success of the scheme.

Undoubtedly, Airservices and its global contemporaries are hard at work on these issues as a priority. It is what their customers are pushing for in the pursuit of efficiency in a world of rising costs.

It is also the next major step towards the long term goal of gate-to-gate user preferred trajectories.

Flight in four dimensions

ASTRA’s timeline has user preferred trajectories transitioning into research and development and proof of concept demonstrations over the next 12 months. The rollout of UPTs in low density areas is scheduled to take place in 2013 and high density areas after further evaluation in 2015. It’s an ambitious schedule given the hurdles thus far experienced by Airservices in the stepping stone of UPRs.

UPTs strive for a seamless operation from gate-to-gate and beyond, with further savings becoming available through such mechanisms as reduced wastage in the form of holding, both on land and in the air.

Often referred to as 4-D, every event from pushback to parking is carefully timed and choreographed. This is a challenge just in an intra-airline sense.

To consider a maze of other traffic also vying for optimal routes across various FIRs without aligned air routes offers some idea of the work ahead for those involved.

However, Australia and Airservices are not alone. Europe is also seeking answers to growing congestion and improving efficiency in its crowded skies.

Europe’s timeline for 4-D operations is similar, as are many of their issues.

The future

ICAO’s vision for air traffic management is “To achieve an interoperable global air traffic management system, for all users during all phases of flight, that meets the agreed levels of safety, provides for optimum economic operations, is environmentally stable and meets national security requirements”.

At first glance, the streamlining of air routes through optimisation, flex tracks, UPRs and ultimately UPTs seems to meet these goals admirably.

But that is not an easy task when safety, economics, the environment and national security are brought together in the space of a sentence.

These are challenging times for all involved.

The airlines need the savings to remain viable and the service providers, like Airservices, rely on that same viability for their income stream. The survival of both in this dynamic environment is dependant upon each other overcoming the challenges that lie ahead.

Efficient air traffic management will be key to that survival. Through ASTRA’s development of the Australian Air Traffic Management Strategic Plan, we have a road map to the way ahead. To reach fruition, the plan will require every effort from the stakeholders to transition Australia’s airspace management into the next epoch. With such a level of cooperation and more efficient airways, the industry may ultimately prove that the shortest distance between two points is no longer a straight line.