Chelton EFIS introduces aviators to ‘virtual VFR’

 - February 4, 2008, 9:29 AM

In a historic first the FAA has issued a TSO for the synthetic-vision EFIS developed by Chelton Flight Systems of Boise, Idaho. Intended primarily for the high-performance piston and turboprop markets, the system is unique in aviation because of its ability to portray 3-D views of terrain and obstacles and so-called highway-in-the-sky (HITS) guidance cues on a full-color primary flight display.

The first STC’d system was installed recently in a Cessna Caravan at Yingling Aviation in Wichita, where the airplane was also fitted with a new executive interior before being flown to its new owner, a private businessman in Taiwan. Named Flight Logic, the Chelton package includes a PFD and MFD, air-data computer, attitude and heading reference system and GPS receiver.

Chelton has chosen military-style flight guidance ADI symbology supplemented by HITS navigation for flying precisely between waypoints and while on approach. The idea is simple. Flight Logic creates a series of constantly shifting boxes on the display, through which the pilot flies. As long as the flight-path symbol goes through the HITS box, the pilot can be assured he or she is right on course. Flying with HITS is easy, a big part of the reason the FAA and NASA are so eager to see the technology applied in GA aircraft.

Some have called the technology “virtual VFR” because of its ability to depict an electronic view of the outside world on a flight display. To create its digital surroundings, the Chelton synthetic vision system combines an internal database of the earth’s topography, attitude and heading data and position input from a GPS WAAS receiver. The result is a video-game-like view of the world ahead of the airplane that makes the pilot’s job much easier in weather and at night.

The flight-path marker, which displays the airplane’s projected  path through the sky, allows the pilot to guide the aircraft through the HITS boxes. At the same time, the PFD displays real-time 3-D terrain modeling, with mountains that shift as the aircraft flies along. Also included on the display are airspeed, groundspeed, altitude, height above terrain, density altitude, vertical speed, angle of attack, heading, decision height, actual winds aloft, crosswind component and OAT.

An MFD installed next to the PFD provides navigation, weather and traffic information. Purchase price for the complete package, including all needed wiring and harnesses, is $71,000. Anticipated installation time is about 150 hours.

Not only has the FAA offered its blessing of the Chelton system, it sees the technology as instrumental in future operating environments. As a result, pilots participating in the FAA’s Alaska Capstone project will soon benefit from the Chelton system, flying with the displays in the rugged terrain of the Yukon-Kuskokwim Delta.

“People have been telling us for years that the FAA would never approve this technology,” said Chelton president Gordon Pratt. “In reality, we could never have accomplished this without them.”

The navigation display contains a moving map that uses Jeppesen NavData. It shows flight path and terrain that is near or above the aircraft and satisfies the FAA’s TAWS mandate for turbine-powered airplanes, the company said. Unique features of the moving map are a horizontal projected path showing a wind-corrected track of the aircraft one minute into the future and a dead-stick glide area depiction that is constantly corrected to account for turns, wind and terrain. An HSI/RMI presentation is also included on the nav display.