Capstone is an accelerated Federal Aviation Administration (FAA)
effort to improve aviation safety in Alaska. The program includes the
installation of ground infrastructure, global positioning satellite
(GPS)-based avionics, and data link communications in commercial
aircraft serving the Yukon-Kuskokwim Delta/Bethel area. No state relies
as heavily upon aviation as Alaska does to provide many of the bare
essentials of life. Few environments are as spectacular, or as
unforgiving, as Alaska. In fact, it ranks at or near the bottom in U.S.
aviation safety because of its terrain, climate, and lack of such
infrastructure as weather observation stations, communications, and
radar coverage below 10,000 feet, where most general aviation and
commercial carrier aircraft fly. Plans call for up to 200 aircraft to
be voluntarily equipped with Capstone avionics.
The Yukon-Kuskokwim Delta/Bethel
Region of Alaska
of December 2001, more than 140 aircraft had been so equipped by the
FAA and they have logged 127,000 hours of flight time. Furthermore,
about 100,000 square miles of western Alaska airspace is now service by
the Capstone ground infrastructure.
CAASD's Role in Capstone
MITRE Corporation's Center for Advanced Aviation System Development
(CAASD) has been involved in several key elements of the Capstone
- Providing systems engineering and architecture.
- Planning tests and evaluation strategies.
- Building prototypes and operational models.
- Helping evaluate Capstone's radar-like services and system safety.
the FAA's federally funded research and development center, CAASD has
worked closely with the Alaskan aviation industry, the FAA,
manufacturers, controllers, pilots, contractors, and others in
deploying the initial system, in developing Capstone software and
infrastructure, and in conducting tests leading to Capstone's
radar-like services. Furthermore, CAASD is working on and coordinating
standards development for many of the other technologies being tested
CAASD's involvement with Capstone has been ongoing
for several years, beginning as a planning and coordination effort
under the Flight 2000 and Safe Flight 21 programs. Over the past year,
CAASD's direct participation has grown. Since early 2000, CAASD has had
a staff engineer in Anchorage as a member of the Capstone Program
Office, and a number of staff devoting their energies to Capstone in
CAASD's headquarters in McLean, VA. A large contingent of CAASD
Capstone staff were in Alaska in August 2000 to support a major
demonstration of Capstone capabilities, and throughout 2001, CAASD has
continued to support Capstone from Anchorage and McLean. In January
2001, FAA Capstone Program Manager John Hallinan visited CAASD to
present an award to CAASD Capstone staff for their exceptional
commitment to the program.
Capstone Program Manager John Hallinan, front row, far right, presented
CAASD Director Jim Chadwick (front row, center) with a plaque
commemorating CAASD's strong support of Capstone. An accompanying
letter noted "The Capstone Program is technically complex and it deeply
involves many of [the FAA's] lines of business. . . Consistently, over
the past three years, CAASD personnel performed in an outstanding
manner. Their support was invaluable as we progressed on our voyage of
Safe Flight 21 program, of which Capstone is a part, evolved from
recommendations in a 1998 report looking at Free Flight operational
enhancements prepared by RTCA, Inc.–an industry-wide aviation advisory
group. The first phase of Capstone is to equip small commercial
aircraft in the southwest region of Alaska. The next phase will target
aircraft in the Juneau region. Linking several FAA safety initiatives,
Capstone is focused on enhancing safety in several areas, including
situational awareness, midair collisions, and controlled flight into
terrain. The program is testing and evaluating the capabilities of
several technologies, including Automatic Dependent
Surveillance-Broadcast (ADS-B), Traffic Information Service-Broadcast
(TIS-B), and Flight Information Service-Broadcast (FIS-B).
the airborne avionics, a network of data link ground stations is being
installed in up to 10 existing FAA and joint-use facilities in the test
area, and connected via existing satellite-based communications systems
to FAA air traffic control facilities. To facilitate the implementation
of the ground network, a common ground station design is being used for
both Capstone and another ADS-B-related project in which CAASD also has
played a significant role--the Ohio River Valley operational
evaluations. A ground broadcast server (the Capstone Communication and
Control Server, or CCCS) and a gateway processor have been installed at
the Anchorage Air Route Traffic Control Center (ARTCC) to receive data
from each remote site and to interface with the existing Micro En route
Automated Radar Tracking System (Micro-EARTS). The Micro-EARTS is
programmed to depict ADS-B targets along with radar targets on air
traffic controller displays. Radar data will eventually be uplinked to
equipped aircraft (TIS-B) and will enable the pilot to see both ADS-B
and radar targets on the multifunction display (MFD) in the cockpit.
Weather information is also being uplinked to the cockpits of equipped
aircraft. In the future, other non-control information, such as special
use airspace status, Notices to Airmen, and Pilot Reports will be made
available. ADS-B aircraft position reports also will be available to
operators for flight-following purposes.
The Capstone evaluation
period, which began in early 2000, initially concentrated on weather
and other information in the cockpit, affordable means to reduce CFIT,
and enhanced capability to see and avoid adjacent traffic operational
enhancements. Part of the Capstone initiative through 2002 is to
evaluate further enhancements. As part of the program, pilots,
operators, safety inspectors, air traffic control specialists, and
technicians will be trained to ensure gaining the greatest benefits
from evaluation activities.
Although not part of Safe Flight 21,
GPS non-precision instrument approach procedures are being prepared and
published for one or more runways at each of 10 remote village airports
in the Capstone evaluation area. Within budgetary limitations,
automated weather observation systems will be installed at many of
these airports to enable air carriers the use of the new non-precision
GPs instrument approach procedures.
The cockpit of a Casa-212 with the
Multifunction Display illuminated in the
center of the panel.
technology is providing the means for air and ground vehicles to
broadcast and receive ADS-B messages via a digital link. Unlike radar,
ADS-B relies on the satellite-based global positioning system to
determine an aircraft's precise location in space. The system then
converts the position into a digital code, which is combined with
information such as the type of aircraft, its speed, its flight number,
and whether it's turning or climbing or descending. The digital code is
updated once per second and broadcast from the aircraft on a discrete
frequency called a data link. On board the aircraft, ADS-B information
from other aircraft is displayed on a moving map display on the MFD,
which can also display terrain and weather information, and a variety
of navigation maps. This ADS-B information also provides air traffic
controllers with a more complete picture of the airspace and can
support flight-following by operator dispatch offices. TIS-B is the
uplink of the position of non-equipped aircraft as seen by surveillance
radar—this can be used as the enabling technology allowing traffic and
other data available on the ground to be transmitted to the cockpit.
Terrain Database, coupled with GPS-derived position data, provides the
means to reduce or even avoid often-deadly CFIT accidents. A graphical
presentation of the terrain relative to the aircraft is presented on a
moving-map display to alert the pilot of potential conflicts and give
the pilot sufficient time to react to the situation. Weather
information uplink from the ground (FIS-B), along with the TIS-B data
described above, can also be presented on the same display, providing a
cost-effective, integrated approach to weather, traffic, and terrain
avoidance for general aviation and commercial aircraft. In short,
enhancements demonstrated in Capstone have the potential to
significantly increase flight safety, system capacity, and the overall
efficiency of flight operations.
Avionics and Infrastructure
goal of the Capstone program was to design an avionics suite that is
compact, multi-functional, and affordable. Part of that challenge was
creating a package that would fit in smaller aircraft and at the same
time would not require major modifications for installation, since the
participating aircraft were almost all small single or twin engine
The Capstone avionics suite is designed to:
- Increase the situational awareness of pilots and help prevent mid-air collisions.
improve air traffic control services in non-radar space by sending
ADS-B position information to the Air Route Traffic Control Center
- Reduce CFIT via a cockpit display and terrain database.
- Increase weather awareness by obtaining real-time weather information via a cockpit display.
MFD: Multifunction Display
Capstone team is exploring one of the major advances in cockpit
technology: the MFD. A digitally powered glass display on the
instrument panel, the MFD gives the pilot a wealth of information in
one place and has several different capabilities depending on how it is
configured. Navigation maps, terrain information, weather information,
and aircraft targets are all presented on the moving map-equipped MFD.
The Universal Access Transceiver Digital Data Link
Universal Access Transceiver, or UAT, is the two-way digital data link
employed in the Capstone system. It is a high-bandwidth, multi-purpose,
low cost data link. UAT was initially developed by CAASD. CAASD has
worked with data link technology for several years, and its work in
related areas of aviation research is part of Capstone's legacy.
Developed under internal research and development funds at MITRE
beginning in 1995, the UAT was originally conceived as a simple,
multifunction broadcast data link alternative for small aircraft.
Following the successful flight demonstrations of ADS-B, FIS-B and
TIS-B as part of CAASD efforts, United Parcel Services (UPS) Aviation
Technologies developed a commercial version of UAT. Subsequently, UAT
was included in the winning proposal by UPS Aviation Technologies for
Capstone avionics and ground stations. RTCA has begun developing UAT
standards, with CAASD again poised to play a key role.
Schematic Diagram of Capstone Avionics
Capstone Communication and Control Server
airborne avionics are complemented by a ground-based system providing
complex communications and processing for weather, maintenance
monitoring and control, and surveillance. CAASD engineers developed the
heart of the ground infrastructure, the Capstone Communication and
Control Server, which provides the following services:
Results: Phase I (Making History)
FAA Capstone personnel with one of Yute
Air's CASA-212 on the apron at Anchorage,
December 31, 2000.
I activities (January 2000-December 2000) sought to have a positive
impact on safety while creating an infrastructure to permit initial
procedures development, familiarize flight crews, controllers, and
avionics installers with modern equipment and future NAS concepts, and
to address certification issues and procedures. Among the major
accomplishments in Phase 1 were:
- Radar-like air traffic surveillance services using ASD-B down link.
- Initial weather uplink and weather cockpit display.
- Cockpit display with moving map navigation.
- Terrain avoidance information in the cockpit.
- An operational ground site at Bethel.
- More than 90 aircraft equipped with Capstone avionics.
the last day of December 2000, Capstone made its way into the history
books. At 3:18 p.m. on the 31st, two aircraft–a Yute Air Casa-212 and a
Northern Air Cargo DC-6–departed Anchorage International Airport for
Bethel. Using ADS-B as an FAA-certified and operationally approved
surveillance source for radar-like ATC services while under visual
flight rules and instrument flight rules, the aircraft appeared on the
screen at the Anchorage air traffic control center. Both were vectored
for an instrument approach to Bethel Airport. En route, the aircraft
were tracked by the Anchorage ARTCC using ADS-B's radar-like
capabilities. About two and a half hours later, with a ceiling of about
800 feet and visibility of 1 mile, they landed on the Bethel runway,
becoming the first aircraft in history to be given such clearance to
This first flight using ADS-B for continuous radar-like
services in normal revenue service was a major event for Capstone and
the FAA. In a December 29, 2000, FAA press release, FAA Administrator
Jane F. Garvey said of this new technology, "[it] has the potential of
filling in huge gaps in radar coverage including vast areas in South
America and Africa, as well as the United States."
results of Phase I have cut a clear path of transition activities by
identifying and addressing National Airspace System implementation
issues. Capstone's system integration approach is validating the
overall safety and efficiency benefits expected from modernization.
Since its initial deployment in 2000, pilots using Capstone's blend of
communications, navigation, and surveillance equipment did not
experience a single controlled flight into terrain accident.
A Look Ahead
Fiscal Year 2002 (FY2002), the Capstone Program will continue its
partnerships with air carriers, avionics industries, and the traveling
public. Work on elements supporting technologies chosen for Phase I
need to be completed so that each element is hardened, validated, and
ready for further deployment throughout Alaska and potentially the
National Airspace System. For example, the process to accept the CCCS
as a NAS baselined and maintained system will be completed for the
initial CCCS deployment.
FY2002 activities will also focus on
completion of Phase I Capstone area requirements in and around Bethel.
Non-precision approach procedures developed and already published will
be supplemented with additional procedures at adjacent village airports
within the Phase I area. To ensure constant and consistent data
collection during the validation period and to provide further safety
benefits to the flying community, avionics installations will continue
for the remaining 60 aircraft. A new CCCS interface will be developed
for the distribution of ADS-B data to commercial companies so they can
provide flight following capabilities to the Alaskan operators. Remote
monitoring and maintenance capabilities will also be developed in the
CCCS and GBTs to reduce the labor and cost intensive maintenance
procedures for remote installations.
Also in 2002, the Juneau
activities will get underway. New, more capable, avionics are already
being procured and will be installed on a limited basis. The
installation of a ground infrastructure similar to the Bethel region
will also begin.