General aviation in Alaska is different. Changeable weather and difficult terrain create an environment where you’d expect most flying to be done on instruments, but an antiquated route structure and limited navaids make this impossible in many places. Yet many towns and villages depend on aircraft to a degree that’s almost unknown in the rest of the country. Alaska’s road network is comparable to Vermont’s—for an area about the size of Texas, California and Montana combined. In Alaska, food, fuel, medicine and (in a few cases) even high-school students move by air—or they don’t move at all!
Combine those factors, and it’s not hard to predict the result—a lot of scud-running that led to an appalling accident rate. “During the 1990s, it was common to have an airplane crash here literally every other day,” says the FAA Capstone Program manager, John Hallinan. “We had about one death every nine days.”
Since 1999, though, a consortium including the FAA, commercial operators, the Alaska Pilot’s Association, the University of Alaska, MITRE Corporation, some avionics manufacturers and individual pilots has cut the accident rate in the eastern part of Alaska by some 40%. The project that made this possible is called Capstone.
Capstone’s key is improved situational awareness—both in the cockpit and on the ground. Two main technologies are used for this system: a global positioning system (GPS) and automatic dependent surveillance-broadcast (ADS-B). Most pilots are aware of what a GPS does for them, but ADS-B may be unfamiliar. It’s similar to a conventional radar transponder, but with a couple of twists. A conventional transponder replies only when interrogated by a radar beam. ADS-B transceivers broadcast automatically, presenting the aircraft position, altitude and speed (based on a GPS) and an identifier. Other ADS-B transceivers pick up this information, so it can be displayed on a multi-function display (MFD) in the cockpit. In western Alaska, ground stations pick up ADS-B transmissions and relay them to air traffic control (ATC) facilities, where they’re displayed alongside traditional radar.
The result: Pilots now can get flight following in parts of western Alaska that are outside radar coverage and receive traffic alerts from other traffic in the area—either from ATC or directly on the MFD in the cockpit. The same display (usually a Garmin MX20) also provides GPS moving-map and terrain indications. So, obviously, situational awareness improves for pilots using this equipment—but that’s just the beginning. ADS-B also can function as a datalink system for weather transmission. NEXRAD imagery in the Bethel, Alaska, area and METARs from many reporting stations are provided over the ADS-B link.
|The FAA’s Capstone project uses a ground-based transceiver and support equipment on Mt. Robert Baron outside of Juneau, Alaska, to relay ADS-B transmissions to ATC facilities.|
The result: A dramatic reduction in the accident rate for aircraft equipped with the Capstone Phase-I avionics suite. A 2004 study by the University of Alaska at Anchorage and MITRE showed a whopping 40% reduction in accidents for Capstone-equipped aircraft in comparison to non-equipped aircraft.
According to Hallinan, “ADS-B takes your GPS position, puts that into a data packet with an altitude and N number, and pumps them out of the airplane once per second. It also can receive that data from other aircraft. We pick up this information on surveillance receivers and transmit it back to the Anchorage center. It has been approved since January 1, 2001, as a substitute for radar in areas where radar coverage isn’t available. It benefits both VFR and IFR pilots—for the first time, it’s possible to get VFR flight following in most of the state. Chief pilots and dispatchers, with appropriate access, can get real-time data showing positions of aircraft both in the air and taxiing on the airport. They’re using it to dispatch fuel trucks, and it allows airplanes to be turned around much faster than they could be otherwise.”
“Below 10,000 feet, probably half of Alaska has no radar coverage,” continues Hallinan. “We’re finding that giving people the option to move from a purely VFR environment to an environment where it’s practical to fly IFR is a big benefit to everyone. Take a look at the approach plate for Juneau—it gives a 2,000-foot or so MDA with two to three miles of visibility required. You need pretty good VFR to get in there, even on an IFR flight plan—and that’s at the state capital. Over in Naknek, we have two villages just five miles apart—but you can’t move from one side to the other by road most times of the year because there’s a river between them and no bridge. There’s only one school, so kids from South Naknek actually go to high school by air. Elsewhere in the state, we have kids commuting by air for intramural sports. Sometimes pizzas for delivery go by air. And the very things that keep people alive here—food, fuel, etc.—goes by air. That’s the way you move here!”
The benefits of Capstone aren’t limited to IFR operators. According to Hallinan, “We’re finding out that our new technologies—ADS-B, GPS-WAAS [or Wide Area Augmentation System] and related systems—help to build our IFR infrastructure as well as to benefit the VFR guys. We have people in the southern part of the state who fly Otters on floats, which help them.”
Phase I was just the beginning. In Phase II, Capstone is being expanded to southeastern Alaska, which has even more demanding requirements due to a combination of extremely mountainous terrain and large bodies of water, leading to frequent ground fog. To meet these challenges, for Phase II, Capstone is expanding to include GPS-WAAS along with synthetic vision systems.
According to Hallinan, “Phase II expands Capstone to exploit WAAS and its related capabilities—including terrain awareness. It also gives us something called required navigation performance [RNP] by turbojet operators, allowing for reduced separation. At Juneau, Alaska Airlines developed an approach for RNP-equipped airplanes that get down to much lower minima than the regular instrument approach.”
|Alaska’s difficult terrain, unpredictable weather and high rate of aircraft accidents prompted the FAA to conduct the Capstone project in Alaskan airspace, reducing the number of GA accidents in the state by 40%.|
Not all the challenges for Capstone have been technical. Convincing the FAA’s regulatory branch to accept Capstone equipment as a substitute for conventional navaids has required a great deal of work on Hallinan’s part: “Once in a while, we have problems with other orphan regulations that addressed really important problems years ago, but stand in the way of modernization today. We had to get special approval to deviate from these rules to requirements for ground-based navigation systems. The flight standards folks interpreted the existing rules as requiring equipment to receive ground-based navigation signals for operators flying IFR. Thanks to SFAR 97, in Alaska, only WAAS is required today for IFR operations.”
Beyond Phase II, there are plans to expand Capstone to the entire state of Alaska in Phase III, which is expected to take place between 2005 and 2008 (budget permitting). This will make Alaska, in many ways, something of a laboratory for the entire national airspace system—and have no doubt, Capstone technology is coming to the Lower 48. The FAA already has a program under way to put ADS-B into the eastern seaboard as well as Pres-cott, Ariz., areas. The joint FAA-NASA Small Aircraft Transportation System (SATS) program is experimenting with how technology similar to Capstone’s Phase II could be used to improve IFR safety at smaller airports, including Unicom fields.
The benefits of Capstone are all very well, but what does it cost to add the equipment to an existing airplane? According to Hallinan, who owns a Cessna 182 that hasn’t yet been Capstone-equipped, “You can get a WAAS receiver for around $10,000—and I expect that to drop. A Garmin MX20 runs about $5,000, while an ADS-B datalink transceiver costs in the realm of $7,000. Installation is extra—every airplane is quite different! Phase II is a lot more complex.”
John Hallinan doesn’t believe that Capstone should be limited to operators with the budget for this kind of equipment: “We’re also looking at portable technologies to allow VFR pilots to get the advantages of ADS-B and in-cockpit weather affordably. I’m not going to put an MX20 in my personal C-182, but I might be able to carry a Tablet PC. We’re looking at how to provide some of the navigation performance in a package that private pilots can afford. That’s a chunk of aviation that’s both important and frequently overlooked. We want to be sure that safety improvements extend to everyone, not just the high-end guys!”
When he was asked about the XM WX satellite radio receivers that are becoming a common way to get low-cost weather in the cockpit, Hallinan says, “We’re looking at that. Within reason, we believe that the more information we can put in the cockpit, the better!”
And about the future, Hallinan comments, “As the technology, standards and regulations mature, I expect us to see WAAS-based routes, ADS-B systems, and all of that stuff, extended throughout the state. We’re also looking at the capability of using the Iridium satellite telephone system to enhance our ADS-B datalink. All of this technology is available commercially. It comes down to the FAA getting things approved. We need to commission WAAS-based approaches and airways. We need to allow ADS-B in more centers, which actually outperforms radar!”