Chelton Flight Systems | Reviews/Articles

Pilot Profiles

It's only natural for us to be enthusiastic about the FlightLogic system and say wonderful things about it. And chances are, you've also seen claims about "breakthrough capabilities" or "revolutionary functionality" made by competitive EFIS products. But one way to distinguish hype from reality is to see what aviation editors and opinion leaders have to say about FlightLogic:

As part of a project the FAA calls Capstone 2, the government is installing, free of charge, synthetic vision and moving map displays built by Chelton Flight Systems of Boise, Idaho, into as many as 200 aircraft of commercial operators in the Juneau area of southeastern Alaska. The Chelton system, which replaces traditional "steam gauge" dials and gauges, features two liquid crystal displays that can present data in ways seen before only in research applications and video games. Full Article
Aerospace America, June 2004

"The Chelton SVS [Synthetic Vision System] also has a trait that has become synonymous with synthetic vision: highway-in-the-sky (HITS) flight path guidance that presents a series of target boxes that a pilot or autopilot can use to navigate in lateral and vertical dimensions along departure, en route and arrival tunnels."
Business and Commercial Aviation, May 2004

"HITS technology is a long-touted idea that never quite got off the ground before now. FlightLogic's HITS display, the first of its kind to gain FAA certification, is simple and straightforward, creating a series of constantly shifting boxes through which the pilot flies to stay on course."
Aviation International News, May 2004

"Phase II is general aviation, but the Chelton EFIS would be at home on a spacecraft."
Avionics News, February 2004 (Regarding Capstone Program Phase II)

"Sierra Flight Systems - now Chelton Flight Systems - began work on the Chelton HITS/SVS PFD in 1997. Sierra took new PFD concepts one step further with its HITS flight director mode, years ahead of some government-funded programs and the work of more established competitors."
Professional Pilot, January 2004

"The Chelton FlightLogic Synthetic Vision EFIS will offer such advanced capability to the small aircraft operator that the certification of this system will be eagerly awaited by many aircraft owners."
Avionics News

"Of all the displays we've seen, we've been most impressed with Chelton's SV/HITS [Synthetic Vision/Highway In The Sky. Further], Chelton, with its experimental systems, has the most systems flying."
Aviation Consumer

We believe that once you read how impressed the overwhelming number of aviation experts are with FlightLogic, you'll appreciate just how much more advanced this system is than anything else out there.

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Chelton's FlightLogic Synthetic Vision EFIS by George Lewison
Avionics News, October 2002

Chelton Flight Systems, which produces many avionics products, has a line of multifunction flight instrument displays that was developed by Sierra Flight Systems. Sierra Flight Systems was acquired by Chelton Flight Systems last summer and is now a part of the Chelton company. Most important however was the retention of the Sierra Flight Systems personnel. There is no substitute for knowledgeable management, engineering and production personnel. Because of the technical capability of theses new Chelton multifunction displays and their reasonable cost, they have been chosen for the phase two demonstration of the FAA Capstone project.

The reason for the selection of the Chelton Display Systems is due to a number of factors. They are reasonably priced so that they may be installed on a wide range of general aviation aircraft. They have accurate approach instrumentation, a terrain awareness warning system, and excellent en route mapping, but in addition offer a Synthetic Vision mode that provides superb and advanced situational awareness never available before on a small general aviation aircraft.

Sierra Flight Systems had first shown the EFIS-1000 and EFIS-2000 at the AEA Convention and Trade Show in Reno in 2000. Those units were designed for installation in aircraft with an experimental license and as a result did not require TSOs. These two EFIS systems are the basis for the development of the new Chelton TSO'd and STC'd EFIS System that will be used in phase two of the FAA Capstone Program in Alaska. The only difference between the EFIS-1000 and the EFIS-2000 is that the EFIS-2000 has a solid state AHRS System that is installed along with the EFIS. It is interesting to note that the EFIS-1000 can be upgraded to an EFIS-20000 simply by the addition of the AHRS System.

In the original Sierra EFIS-2000 Synthetic Vision System, everything is built into the multifunction display indicator with the exception of the AHRS, which is a separate unit and the GPS system that is actually built into the GPS antenna. There is also a small panel (EAU) that is utilized for air data and to convert engine parameters for display. When this unit is installed on the instrument panel, it can display the engine data in digital format.

The EFIS-2000 contains a special ruggedized computer processor unit that operates at 333 MHz and contains 32 MB of RAM and a 4.3 gigabyte hard disk. There is also a slot for a Smart Media Card Reader for update of the database. In addition, the digital flight recorder logs all of the engine and flight data. It should be noted that the GPS receiver contained in the GPS antenna is a 12 channel parallel tracking GPS receiver. A single AHRS unit can provide reference information to an EFIS-2000 system with up to four display units.

The information display ability of the EFIS-20000 is what makes it such a valuable asset to the flight crew. On the EFIS-2000 the primary flight display utilizes military style flight path marker symbology. It provides 3-D Skyway navigation for waypoints and approaches. It also has real time 3-D Terrain modeling based on the USGS database. In addition real time 3-D towers, antennas and other obstructions are depicted at their locations. It has a pitch limit indicator and an automatic unusual attitude recovery display system. There is also the new Highway-In-The-Sky symbology as well as multiple declutter modes.

When the navigational display is selected, it has a vector based moving map with a Jeppesen database. It is also capable of full weather and air traffic display capability. In addition, and one of the most important features, is the terrain incursion display. It also provides winds aloft and the crosswind component, density altitude, true airspeed, ground speed and outside air temperature.

A complete EFIS-2000 System consists of a primary flight display instrument, a multifunction display instrument, an engine/air data unit, an attitude/heading reference system (AHRS) and a GPS system. In addition other systems may be interfaced such as a Stormscope, a TCAD System and an autopilot. With the other systems installed, a small single engine aircraft can actually have all of the navigation ability that in the past was only possible with much larger aircraft.

Each of the EFIS-2000 indicators is 7.91 inches wide by 5.575 inches high by 2.95 inches deep. They each weigh 4 pounds and will operate on 10 to 28 volts DC. The engine/air data unit is also designed for instrument panel mounting and is 5.22 inches wide by 2.85 inches high by 4.5 inches deep and weighs 1.4 pounds. It will operate on any voltage between 9 to 28 volts DC. The AHRS is designed for remote mounting near the aircraft center line. It is 4.63 inches high by 3.13 inches wide by 5.78 inches deep. It weighs 2.0 pounds and also operates on 10 to 28 volts DC. While the EFIS-2000 can use alternate GPS Systems, its own GPS system is self-contained in the GPS antenna. The complete GPS receiver/antenna is designed for remote mounting on top of the fuselage. It is 1.0 inches high by 2.2 inches wide by 3.9 inches deep and weighs just 0.3 pounds. It operates on 9 to 35 volts DC. The Chelton equipment supplied for the phase II part of the FAA Capstone program for each aircraft will be two electronic flight instrument display panels, an AHRS systems and an air data unit. In the FAA program there will be a primary flight display instrument and a multifunction display instrument. It should be noted that the Chelton system is capable of handling a total of four displays. This capability would provide the aircraft owner with the option of buying a second set of instruments for the copilot's side if desired. These systems communicate with each other through a standard RS-232 data bus as well as RS-422 and ARINC-429. The initial part of the Capstone demonstration is currently going on in Alaska.

While the equipment currently operating on the Chelton Cessna aircraft is under an experimental approval, the program intent is to provide for the installation of the new components and the certification of the Chelton Multifunction Display System on the aircraft. This certification will be accomplished through the Anchorage Alaska FAA ACO. There will be a change in the size of the display panels in the certified system in order to provide more compatibility with other avionics equipment currently being installed on general aviation aircraft instrument panels. However, the LCD display portion of these indicators will remain the same size. In addition to the size change, all FAA requirements for an FAA TSO'd type of equipment will be met by the Chelton Display System.

The new Chelton Display Systems that will be certified by the FAA are currently to be designated as a "Chelton FlightLogic Synthetic Vision EFIS." The new displays will be 6.25 inches wide by 5.48 inches high by approximately 3.95 inches deep. Two display instruments will be provided for each aircraft in the FAA Capstone II program. One of the displays will be used as a Primary Flight Director and the second, as a Multifunction Display Panel. In addition to these two displays, a Chelton AHRS Attitude, Heading Reference System will be installed and a remote located Chelton air data unit will also be installed.

Furnishing data to the Chelton Display Systems will be a TSO'd GPS receiver along with a Wide Area Augmentation System (WAAS) for correction of position error. This will be one of the first certifications of the Wide Area Augmentation System for an aircraft in any FAA region. It will add a new level of accuracy to the GPS navigation information which already is of high resolution. In addition to the FAA supplied components of the Capstone Phase II operation, the individual operator, if they so desire, can procure and couple for display on the multifunction indicator auxiliary devices such as a Stormscope and TCAD system.

It must be kept in mind that the TSO'd version of the Chelton Electronic Flight Display System is currently under development. There could be some changes in the final version of this system due to FAA requirements, but in general it will probably be very close to the description of operation that follows.

[NOTE: specifications/dimensions have changed since this article was printed; please request a brochure for the most accurate, up-to-date information regarding the FlightLogic system]

The Chelton EFIS includes an integrated auditory caution/warning advisory system that monitors a wide variety of parameters and provides the required auditory annunciations for conditions that require pilot awareness. Audio annunciations take the form of either a voice warning or a high/low tone warble.

Annunciations are grouped into three categories. "Warning," "Caution" and "Advisory." Warnings are also accompanied by a visual red flag and repeat until acknowledged by the pilot or the condition is corrected. Cautions are accompanied by an amber flag and are only annunciated once. Advisories are accompanied by a green flag or no flag depending on condition and are indicated by either a voice annunciation or a warble.

The two Chelton TSO'd FlightLogic Synthetic Vision Display instruments will look essentially the same except that the primary flight instrument will have a turn and slip indicator at the center bottom of the instrument. The multifunction indicator normally would not be equipped with a turn and slip indicator. Each of these indicators has two control knobs. The lower left knob is for display brightness and the lower right knob is for control functions. There are a total of eight selector buttons on the sides of each of the indicators—four on the left side and four on the right side.

The left hand knob at the bottom of the display instrument is the instrument brightness control. This knob turns clockwise to increase screen brightness and counter clockwise to decrease screen brightness. Pushing the brightness control knob in while turning it adjusts the brightness of the turn and slip indicator and the back lit engraving on the side buttons on the indicator.

The right hand knob at the bottom of the display instrument is used both to select menu items and enter alphanumeric characters. This is accomplished by turning the menu control knobs to highlight the desired menu or character and then pushing the knob in to enter the selection. The menus that are displayed in the lower right hand corner of the screen are controlled by the menu selection knob. All other menus are selected by pressing the adjacent corresponding menu selection button. There is one additional function possible with the two rotary knobs at the bottom of the instrument. Simultaneously pressing and holding the right and left control knobs in and holding both will provide a command for reinitializing the system.

Another important component of the Chelton Display System is the remote air data unit. The remote air data unit is a unit that converts analog signals from the pitot static system to a digital format that can be interpreted by the computer in the display panels. The unit is approximately 3 inches by 4 inches by 4 inches in size. It weighs approximately 1 pound and operates on 12 to 28 volts DC. The remote air data unit supplies such information as altitude, air speed, vertical speed an outside air temperature, etc.

The AHRS, which is a remote mounted unit, supplies primary information on aircraft attitude and heading reference information. This unit contains a solid-state attitude and heading gyro. The AHRS senses aircraft attitude and heading information and converts it into digital data signals that are sent to the computer-processing unit in the display panels. Internally, the signals from three solid-state angular rate sensors are coordinated, transformed and integrated to produce normal attitude and heading outputs that reflect normal aircraft coordinates.

The signals produced by the rate sensors are then compared against a triaxial accelerometer and a triaxial flux gate magnetometer to derive short-term errors. The errors are filtered over a long term constant and are used to adjust biases in the system to increase the accuracy of operation in the earth's gravitational and magnetic fields. The AHRS is a microprocessor-based device using a 16-bit A/D converter and a 12-bit D/A converter. The AHRS attitude and heading data are output at the rate of 70 hertz. With this output rate, the maximum tractable roll rate is 200 degrees per second.

The engine should first be started prevent any voltage spikes effecting the AHRS data. The air data system protection from spikes exceeds the FAA requirements, however this is just good operating practice. When the AHRS is turned on, the aircraft should remain stationary during the short time it takes for the AHRS to begin operation. On start up, the AHRS performs a self-test function and initialization. This takes about 10 seconds. If the aircraft is moving during this period it may not initialize properly which would make attitude and heading data unreliable. If for some reason power should be interrupted during flight, the AHRS can be reinitialized by maintaining straight level flight for about 10 seconds after restoring power. Any errors that have occurred during this process will work themselves out in one or two minutes.

Of great interest to the operator and real step forward in situational awareness on a small aircraft is the ability of the Chelton Display Systems to provide a "Synthetic Vision Display." The Chelton indicator combines analog, digital and pitot static information along with high resolution GPS navigation information, which is overlaid on a virtual background of the outside world. This background of information is stored in the Chelton indicator's terrain database. Objects that are shown in the virtual background include terrain, towers, approaches and runways, which are all presented conformal to the real world. In other words, the scale and perspective of the synthetic scene is a replica of what could be seen out of the windshield on a VFR day.

The Synthetic Vision Display is particularly of great advantage when visibility conditions are poor as it gives the pilot a much greater opportunity to make a safe approach to the runway. Of great importance to the accuracy of the display is the requirement to have the highest resolution available from the GPS system on board the aircraft. While GPS information is quite good at the present time, the FAA has made the determination that they are going to certify WAAS in the Capstone Phase II program. This will refine the accuracy of the GPS navigation information and remove much of the remaining error from the GPS position data.

The Global Positioning Satellite System has a constellation of 24 satellites which are orbiting the earth at an altitude of approximately 11,000 nautical miles above the earth. It provides the most advanced technology available today for exact location of objects on the earth's surface or above the earth's surface such as an aircraft. Under ideal conditions, GPS accuracy could be as good as plus or minus 4 meters. However a number of factors can affect this accuracy including availability, satellite geometry, and multi-path error. As a result it is wise to consider the basic GPS accuracy to be roughly between plus or minus 16 to 20 meters. WAAS has been designed to remove much of this error.

A letter of intent has been received from Chelton to "FreeFlight Systems" for the production and delivery of combined GPS/WAAS receivers. FreeFlight Systems of Waco, Texas is a relatively new company but with a background of pioneering in GPS technology. FreeFlight Systems is a rapidly growing company that acquired the business and commuter aircraft products from Trimble Navigation. Trimble Navigation had been one of the pioneers in GPS technology. It will undoubtedly be FreeFlight Systems that will produce and market the first combined GPS/WAAS navigation system that will be certified by the Federal Aviation Administration for operation on aircraft. This will occur during the Phase II part of the FAA's Capstone program.

Wide Area Augmentation is accomplished by determining the amount of GPS error at various ground locations that have been surveyed for position accuracy. The GPS receivers at these locations compare their actual surveyed position with the position furnished by the GPS system. The correctional data is then transmitted to the geostationary satellites which are then able to transmit correction data for the errors occurring in various parts of their coverage areas.

The combined GPS/WAAS receiver is then able to extract the correction date from the geostationary satellite and modify the data from the GPS constellation to a much greater degree of accuracy. The new combined GPS/WAAS receiver is probably based on the existing FreeFlight 2101 I/O airborne IFR GPS Navigation System. It is probably a good guess that two of the channels will be dedicated to the correction data from the geostationary satellites. This brings up the requirement for either a dual antenna or two separate antennas to be installed on the aircraft. All of these engineering details will be resolved in the development program.

The WAAS certification that will be accomplished in phase II of the Capstone program will add additional accuracy to the synthetic vision system as displayed on the Chelton indicators. This combination of technologies will result in providing a capability never before available to small general aviation aircraft for operating under very adverse weather conditions. To a certain extent it parallels some portions of the capabilities of the enhanced vision system that was recently certified on the Gulfstream V aircraft. However it must be kept in mind that the Chelton display is a stored data system. It is not operating in real time and as such cannot display recent changes to obstructions or display other aircraft on the runways or taxiways.

The Chelton PFD is the primary flight instrument and in addition to the synthetic visibility display capability can provide all of the parameters of the new Highway-In-The-Sky format. It normally would be used to display these primary functions although it has multifunction capability. The multifunction indicator is another matter—it would be used for switching between many pages for different aids in navigating the aircraft. There are multiple modes of displaying information. There is a basic moving map display, moving map with instrument approach, conventional horizontal situation display, traffic display, lightning display, airspace marking display, jet route display, missed approach fly up display and one of the most important—terrain avoidance display. In addition the MFD can also be used as the primary flight display instrument.

Terrain is displayed on a moving map in a 30-mile square box centering on the aircraft's current position. Most of the display consists of the terrain ahead and to each side of the aircraft. If the aircraft should turn right or left, a new terrain box will appear that depicts the terrain in the direction of the changed flight program. Terrain in this display is identified as threatening and non-threatening. Colors are utilized to identify different heights of the displayed terrain. Terrain that is shown in dark green areas of the moving map is terrain that is 500 to 2.000 feet below the aircraft's current altitude. Dark brown areas indicated terrain that is at 500 feet below the aircraft altitude. Black areas are more than 2,000 feet below the aircraft altitude. Light brown terrain is terrain that is far enough to the side or too far ahead to be a threat to the aircraft but it is terrain that is at or somewhat above the aircraft's altitude. It should be noted that the color conventions will be changed slightly to comply with TSO-C151 TAWS. Class A requirements make defining relative terrain elevation impossible as it changes due to approach segment, speed, descent and rate, etc.

Terrain that could prove to be a threat is depicted in light and dark red color. The terrain warning areas consists of dangerous terrain that is 30 degrees either side of the aircraft heading with an impact time of two minutes. In addition, terrain that is 30 to 90 degrees on either side of the aircraft with a one minute impact time. Dark red areas indicate immediately threatening terrain. Light red areas provide a buffer of 350 feet en route, 200 feet in terminal approach and 75 feet on final approach. Areas that are depicted in yellow provide a buffer of 700 feet en route, 400 feet in terminal phase and 150 feet on final approach. There is a terrain display indicator in the upper right hand portion of the display. It can be pilot selected to "TERR ON" or "TERR OFF." In any area with terrain hazards, the pilot must be sure that the terrain function is on.

The Chelton displays may be interfaced with the Ryan TCAD System for display of air traffic around the equipped aircraft. When interfaced to the TCAD System the airborne traffic is displayed on the moving map as symbols that are based on the level of threat. The traffic symbols consist of colored icons to represent the level of threat. A filled yellow circle represents traffic in the immediate vicinity of the equipped aircraft that could represent a definite threat. A blue filled diamond represents traffic that is within six nautical miles and within 1,200 feet from the altitude of the equipped aircraft. And open blue diamond indicates traffic that is more than six nautical miles away and more than 1,200 feet from the altitude of the equipped aircraft.

The relative altitude of the target aircraft is shown by two numbers with a plus or minus sign to indicate if the traffic is above or below the equipped aircraft. For example +05 would indicate 500 feet above the equipped aircraft. In addition, traffic alerts are annunciated with an audible warning of "TRAFFIC" and an amber traffic flag will show on the indicator. Traffic position in relation to the equipped aircraft is shown by a circle of asterisks around a centered aircraft symbol. This enables the crew to identify the clock position of the intruding traffic.

In a single engine aircraft where installation of a weather radar system is not practical, the installation of a Stormscope can provide for a reasonable measure of weather avoidance and also provide a warning of areas that could have severe turbulence. The WX-500 Stormscope may be readily interfaced with the Chelton multifunction display system. Lightning strikes may be displayed on the moving map or on a dedicated lightning display page.

When the Stormscope is displaying data on the Chelton multifunction indicator, the strikes initially are displayed as yellow lightning bolts in the exact location that they have occurred in relation to the aircraft position. After 30 seconds the lightning bolt changes to a large yellow plus sign. After two minutes it is reduced to a small yellow plus sign and after three mutes the symbol is removed from the display. Lightning may be displayed in either cell mode or strike mode. Strike mode shows every strike detected. In cell mode, the WX-500 filters the strike data to display storm cell areas which should be avoided. There is also an audio annunciation of "lightning" when it is within 30 minutes and within 30 degrees of the current aircraft heading. It also produces an audio annunciation when the lightning strike is within 15 minutes or 30 nautical miles in any other direction.

Fuel flow information is also furnished to the multifunction display panel. With this information and pilot entry of pertinent information such as total fuel on board, etc., the multifunction display panel can also provide all of the requirements for fuel management on the aircraft. It will allow the pilot to determine during flight what its fuel situation is in relation to the destination that has been programmed into the computer. This is another safety factor for the small aircraft operator as the fuel totalizer capability of the multifunction display can predict in advance if there will be a fuel problem in reaching the final destination.

The Chelton FlightLogic Synthetic Vision EFIS will offer such advanced capability to the small aircraft operator that the certification of this system will be eagerly awaited by many aircraft owners and certainly by avionics shops that can provide for the installation of these advanced avionics systems. It will not only make the small general aviation aircraft much safer to operate but it will also be a step forward to equip that type of aircraft to operate in the CNS/ATM air traffic environment of the future. This development and coming certification of the Chelton displays will make it possible for many Aircraft Electronics Association shops to provide a much needed safety addition for many of their small general aviation aircraft customers.