U.S. and European aviation authorities agree that air traffic will double, possibly even triple, by 2025, and air traffic managements worldwide are busy devising solutions to meet this challenge, with new technologies and new procedures expected to be introduced gradually in the next several years.
But the air-freight industry, in which on-time performance is second only to safety, doesn’t want to–and can’t afford to–wait that long. To that end, UPS of Louisville, Ky., has continuously sought ways to use technology to beat the clock.
In 2000, the company, the eighth largest air carrier in the world, was demonstrating the time-saving value of ADS-B for pilot self-separation from other traffic at night; at the time the system was still virtually unknown. The company viewed self-separation, avoiding excessive spacing under ATC “procedural” rules, as a means of achieving significant savings when inbound freighters converged on Louisville in the early morning hours. In those early demonstrations, five Boeing 727s held precise in-trail spacing–monitored but unassisted by ATC radar–as they took off, flew a large rectangle around the Louisville airport and landed.
SafeRoute Will Supplement ADS-B
The FAA will begin its nationwide ADS-B implementation in 2010, and UPS aircraft will be ready. But they will also carry SafeRoute, a sophisticated software program built by Phoenix-based Aviation Communications & Surveillance Systems (ACSS). SafeRoute will integrate ADS-B, GPS, TCAS, TAWS, FMS and ACARS, with its information displayed on dual Class 3 EFBs. (ACSS officials told AIN they are studying Class 2 applications.)
SafeRoute will provide two essential functions. On the ground, the EFB’s surface maps will show ramps, taxiways and runways, plus the position and heading of the equipped airplane, as well as those of all other aircraft. They will also provide runway occupancy alerts, turning runway outlines to red when an aircraft enters a runway for takeoff, or is about to land, and to amber if a landing aircraft has touched down and is decelerating to a turnoff.
In addition, UPS ground controllers will use SafeRoute displays to release loaded aircraft in a timed stream to the runway, minimizing takeoff delays and fuel burn. Incoming freighters can be directed to their unloading gates along the most expeditious taxiways.
But SafeRoute’s major advantage is in the air, when large numbers of inbound airplanes converge from all directions in the early-morning rush hours, unload and reload, and then depart. UPS’s Global Operational Center at Louisville coordinates the departure times of all aircraft from outlying airports, to produce a constant arrival stream. This is based on en route flight times, which vary with aircraft type, payload, wind and other factors, and includes integrating arrivals from the central U.S. or the East Coast, which won’t take off before West Coast airplanes are well on their way.
This system puts inbound aircraft into a fairly cohesive stream, but SafeRoute’s merging and spacing program will provide a major advancement. The program monitors all inbounds within about one hour’s flying distance and calculates their optimum maneuvers to join the arrival stream at precisely spaced intervals, and at precise times and altitudes.
Individual merging instructions are presented graphically on the EFBs, showing the relative positions and intended merge paths of all other aircraft. In addition, the EFBs show command airspeeds required to merge at the right place and the right time, and then the speed required to maintain the correct spacing thereafter. Initially, 180-second in-trail spacing will be used but the eventual target is 120 seconds.
SafeRoute then directs the stream to the top of descent point of the continuous descent arrival (CDA) procedure to the runway, where the crew reduces power to flight idle to maintain a steady descent to 1,500 feet at the final approach fix. UPS tests of CDAs in 2004 demonstrated average savings of two minutes and 360 pounds of fuel per flight, with noise reductions of up to 6 dB and significant reductions in NOx, CO and other emissions.
After the airplane crosses the final approach fix, the EFBs continue to show its progress, even when the preceding aircraft is in sight, since in lower-visibility conditions, or with patches of low cloud, that aircraft might disappear briefly from view. In such cases, the pilots can use the EFBs to conduct CDTI assisted visual separation procedures, to accurately maintain position. As the aircraft nears the runway, the EFB display will automatically switch to the surface presentation, extended out beyond the aircraft, with increasing scale as the airplane approaches the runway.
Four UPS Boeing 757s are currently flying pre-production SafeRoute systems for certification, procedure evaluation and development. The rest of the fleet will be equipped during their heavy maintenance checks over the next two years. UPS aims to have its first fully certified installation flying on August 28, to mark the company’s 100th anniversary.
With SafeRoute, UPS will again be showing the way of the future. Eurocontrol is currently evaluating the system, and the productivity gains and flow management benefits have attracted a high level of interest among European airlines with major hubs. The merging and spacing capability is also an important aspect of the FAA’s NextGen airspace plan, particularly in its proposed Super Density Terminals of the future, where it will be a key element in the required total system performance rules that will become the admission ticket for entry.