The Largest Security-Cleared Career Network for Defense and Intelligence Jobs - JOIN NOW


KC-135R Stratotanker

Pacer CRAG (Compass, Radar And GPS)

The Pacer CRAG (Compass Radar and Global Positioning System) Program represents the Air Force's commitment to modernizing the KC-135 refueling fleet to extend the functional life to 2040, the airframe's projected decommissioning date. The Pacer CRAG avionics upgrade to the KC-135 fleet is a commercial off-the-shelf modification program will eliminate the need for a navigator on most missions. Pacer CRAG upgrades allow the aircraft to be flown by a pilot, co-pilot and boom operator. Older KC-135s are flown by a four-member aircrew, which includes a navigator. The new design could also quickly be reconfigured for a navigator if the mission requires.

The existing cockpit consists of electro-mechanical equipment of 1950s technology with individual control panels and instrumentation distributed throughout. Failure rates are high and repair capability has been restricted significantly as technology has changed. Not only are repairs to the KC-135's existing avionics suite costly for the Air Force, but they also mean more down-time for the tanker while repairs are made. Modem commercial airplane avionics are much more reliable than those aboard the KC-135.

The project provides for a major overhaul of the KC-135 cockpit to improve the reliability and maintainability of the aircraft's systems. In addition, the program meets the congressionally mandated requirement to install the global positioning system in all Defense Department aircraft by the turn of the century. Technology like Pacer CRAG has been used in the civilian industry in the United States and Europe for about 10 years.

Modifications include state-of-the-art color weather radar, improved compass and radar systems and an on-board global positioning system. An additional safety measure, the traffic collision avoidance system or TCAS, was also installed which helps with formation flying. The Pacer CRAG digital system includes a more accurate and reliable altimeter, compass, airspeed indicator, and other navigational equipment. It will replace the KC-135's outdated inertial navigation and doppler navigation systems.

One of the biggest benefits is the system allows pilots to view several functions through multifunction glass displays. As a result, pilots can concentrate on one area to view certain functions rather than looking at a number of instruments to get the same information. Using the improved radar, pilots can detect cloud formations, wind shear and other weather hazards. With GPS, pilots can identify their position anywhere in the world within a few meters. The system provides exact aircraft positioning by using satellites and also calculates the speed, bearing and altitude of the aircraft. Before deciding to acquire the system, some AFRC officials expressed a concern about overloading KC-135 pilots with too many tasks. But the results of 45 air refueling test flights, as well as the system's benefits, put these concerns to rest. Pacer CRAG equipped aircraft have proven in-test to be very challenging for instructor qualified pilots.

Although Pacer CRAG is good news for KC-135 pilots, giving them increased capability, the story is not the same for navigators. The heart of the overall system is a state-of-the-art flight management system. Using this, pilots have the added ability to plot their courses in the training facility, download the information to a data card and then upload it into the aircraft. This capability, combined with the others, eliminates the navigator position. Since 1992, the Air Force reduced active-duty manpower by more than a third. These reductions left few career fields untouched, but a heavy shortage of mission-ready navigators resulted. Within the commercial airline industry, technological advancements led to new cockpit designs that allow the removal of flight engineers from commercial aircraft. Updating the antiquated and unsupportable systems on the KC-135 reduces crew workload to the extent that navigators are not needed for most missions. The benefit: more navigators are available for other special-airlift and tanker missions that require their expertise.

AMC developed an integrated program to enhance KC-135 cockpit avionics and reduce or eliminate the navigator requirement in KC-135. The initial program to replace Compass, Radar and install GPS systems Operational testing led to addition of Traffic Advisory and Collision Avoidance System (TCAS). TCAS was an off-the-shelf fix to problems with formation station-keeping. Cost increased from $426.3M to $686.5M due to the TCAS requirement. Other recent additions to the Pacer CRAG program include , Standby Air Data Indicator [ADI] and an Advanced Central Air Data Computer (CADC) for Reduced Vertical Separation Minimums (RVSM) certification an Enhanced Ground Proximity Warning System (E-GPWS), and a Reduced Vertical Separation Minima (RVSM) Compliant Air Data Computer. These systems will serve as the foundation for future Global Air Traffic Management (GATM).

By 2010, the global air traffic control system is expected to undergo significant change, requiring extensive modification to U.S. military aircraft communication and navigation systems. Growth in air traffic volume is spurring initiatives to manage increasingly congested airspace and improve safety. Global Air Traffic Management (GATM) technology is needed to comply with proposed changes; aircraft without GATM equipment will be prevented from using heavily traveled air corridors. Exclusion of U.S. strategic mobility aircraft from the world's busiest air routes will increase fuel costs and travel time while decreasing allowable cabin loads and delaying force deployments. GATM elements include data links replacing voice communication, integrated global positioning and flight management systems, and automatic aircraft position reporting instead of radar monitoring.

As an added safety measure for formation flying, a traffic collision avoidance system will be installed to give pilots the ability to see other aircraft and will provide advance warning of possible mid-air collisions. In early 1997, the military decided that TCAS was needed and added it to the Pacer CRAG contract as part of an engineering change proposal. TCAS was added to Pacer CRAG because in the test phase the radar failed to adequately detect other aircraft during formation flying.

Directed by Congress for all DOD platforms by the year 2000, Global Positioning System receivers provide aircrews with near-pinpoint navigational accuracy. These new systems primarily are controlled through flight-management computers that automate many aircrew functions and reduce the overall workload.

The new radar, which displays weather intensities in color, requires less interpretation to determine weather severity. The current APN-59 radar has a high failure rate, which results in annual radar repair costs of more than $30,000 per aircraft. The radar has over 50 vacuum tubes, similar to those used to test black and white televisions at corner drug stores in the 1950s. Another drawback of the current system is a black and white video display for weather data, which requires a lot of analysis that increases crew workload and fatigue. Another new, and potentially lifesaving, feature of the radar is its ability to predict wind shear, a powerful force that literally can drive aircraft into the ground. Visual and aural warnings allow the aircrew time to avoid areas of hazardous wind shears and microbursts. All radar data is displayed on two new multifunction displays located at the pilots' center console and the navigator station.

Besides improving the KC-135's operational capability, the Pacer CRAG upgrade also reduces maintenance-related costs. During a 1994 study that compared existing KC-135 maintenance costs to the Pacer CRAG-equipped aircraft maintenance costs, the Air Force found the Pacer CRAG is cheaper and easier to maintain. In this study, the mean-time-between-failures, time-to-repair and maintenance costs were compared between a fleet KC-135s and the same number of Pacer CRAG-modified aircraft. The study found that the Pacer CRAG-modified aircraft flew 538 more hours before experiencing any failure, and maintainers spent an average of 30 minutes per repair on these systems. On the non-modified KC-135s, the average repair time was 168 minutes. This study also revealed that the Pacer CRAG-modified airframes maintenance costs would be $10.2 million a year less than the non-modified KC-135s. The comparison was based on a fleet of 600 aircraft with 175,000 cumulative flight hours and 245,000 operational hours.

Both the radar and TCAS use off-the-shelf products, so there aren't a lot of modifications required. That makes this program unique compared to many acquisition programs in that they take existing commercial hardware and adapting it for military use.

Past management of critical milestones has required a team effort, and that same effort and tempo will be essential to direct the program to completion. Acquisition reform is ongoing throughout the Department of Defense. Under the Air Force's Lightning Bolt Initiatives, military specifications are removed whenever possible. Emphasis on procuring commercial components for use in weapons systems is reducing procurement time and cost. When possible, combining milestones contributes to shorter schedules and cost reduction as well. In the past, procurement of new aircraft and equipment involved numerous key players at different program phases. These key players are now involved in the entire process, from requirements definition to delivery. The emphasis is on the integrated product team (IPT) and its members' commitment and involvement in every decision. As the prime contractor, Collins Avionics and Communication Division is an integral member of the product team.

The major overhaul of the KC-135 cockpit began in 1992. The Air Force issued a solicitation for PACER CRAG in May 1995. The PACER CRAG Request For Proposal (RFP) team used available tools, within the acquisition community, to help refine their program. PACER CRAG embraced acquisition reform by establishing a program to procure commercial off-the-shelf, non- developmental item equipment. They removed multiple Military Standards & Specifications (MIL STDs/SPECs) from the RFP under the acquisition reform streamlining initiative. Additionally, under the Lightning Bolt Initiatives, the RFP Support Office was enlisted to support the PACER CRAG program. Together, the PACER CRAG RFP team and the RFP Support Office reduced government mandated Contract Data Requirements Lists (CDRLs) from 335 to 39, MIL STDs/SPECs from 6 to 0, and transitioned from a Statement of Work (SOW) to a performance oriented Statement of Objectives (SOO). The results of this combined effort included savings of approximately $90.2M and an award of a complex contract one week earlier than planned.

The Air Force set up six sites where its approximately 550 KC-135s are undergoing modifications. When in full production, 45 aircraft will be modified each quarter until all 602 KC-135s are upgraded. One modification site is at March Air Reserve Base, CA, the only joint Guard and Reserve effort involved in Pacer CRAG. The 11-step conversion process is complicated, and workers are improving as they go. The first airplane took 200 days to convert, with a program goal of 45 days.

Join the mailing list

Page last modified: 07-07-2011 02:33:39 ZULU