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Dynon EFIS 10ADynon EFIS 10A
Dynon EFIS 10A

Glass Cockpits, EFIS Components II

Flight and engine instruments used to be the old school style type round gauges we all (well most of us) learned to fly with. These are familiar to everyone. The latest trend in general aviation is electronic displays in cockpits and aircraft are then sometimes called 'New Generation' or NextGen by their manufacturers.

You will see add-on EFIS like the Dynon Avionics series to integrated systems with 8", 10" and even 15" color LCD screens (daylight visible!) from Garmin, where even the radio's (COM and NAV), transponders and engine instruments are fully integrated.

These can be coupled to an autopilot (integrated too) and programmed to fly the entire route and instrument approach. You still would have to do the landing yourself.

Installing a system like this saves weight and cleans up your panel. It also means that you could do without a vacuum system and remove the hoses, pump and hardware (more weight savings). All of this could mean a single point of failure in the cockpit and some aircraft manufacturers have started offering non-integrated panels to be more flexible.

But even with the sixpack we normally used to have, would you go flying if your altimeter did not work?

EFIS Components, II

The system uses a number of separate components to display all of its possibilities. Some manufacturers sell these sometimes integrated inside the display unit as to reduce the wiring in the aircraft. In case of the magneto meter (flux valve) it might not be a good thing as the engine (large part of metal) can be too close in some aircraft and influence readings.

Air Data Computer & AOA

Air Data ComputerAir Data Computer
Air Data Computer

This system uses pitot and static pressure combined with total air temperature to calculate mach number, indicated and true airspeeds, outside air temperatures and vertical speeds to be fed to autopilots, transponders and our EFIS systems.

The angle of attack (AOA) shows the pilot exactly when the aircraft will stall under any condition and he will be able to maintain airspeed precisely if he flies by the AOA. A great help with precision landings flown a couple of knots above stall speed.


Used to obtain the aircraft location, ground speed and exact time from satellites orbiting the earth. It eventually supplies information to be used by moving maps and safe taxi diagrams, synthetic vision and the electronic flight bag options.

The GPS receiver is multichannel (12, 20 or even more) and can be built internally in the system but more commonly external on outside of the aircraft. Large aircraft have them on the outside on the top of the fuselage. The receiver needs an unobstructed view of the sky for good performance although the SIRF III chipsets in some receivers are able to pickup satellites indoors.

Fluxgate or Magnetometer

This device senses the earth's magnetic field and direction for display on screen even without movement of the aircraft, whereas GPS must move to determine direction and with an accuracy of 10 meters (30 feet) directional indication is not very accurate at slow speeds or standing still.

These devices are also able to detect the magnetic dip (declination) and the vertical and horizontal components of the magnetic field.

Some manufacturers (Dynon Avionics) built the AHRS, Magnetometer and ADC in one box, which makes sense production wise. Just remember to install the AHRS on a stable platform (away from electrical wiring) and not on a constantly vibrating piece of skin of the aircraft. Such an arrangement would disturb the accelerometers in the AHRS.

Synthetic Vision

Garmin Synthetic VisionGarmin Synthetic Vision
Garmin Synthetic Vision

A technology which displays in the PFD the terrain ahead and sometimes around the aircraft in combination with colors indicating terrain higher (red), same level (yellow) and lower (green). Gives a great view and the pilot immediately knows if the chosen route leads to terrain too high.

Situational awareness is greatly enhanced with synthetic vision and airports can be shown on screen and last but not least HITS, highways in the sky, can be displayed for easy route flying.

Electronic Flight Bag

This is very handy as it keeps the cockpit free of checklists, maps and approach charts. Updating is very simple through a pc or direct Internet connection and worldwide charts are available from Jeppesen and other sources.

If you are interested in installing an EFB or a pocket type FMS (on a netbook) system in your aircraft then FAA AC 120-76A is must read. Also do read the next article about EFB's and a paperless office in aircraft by Susan Parson.

The checklist function is very handy as it keeps the pilot focused on checking the systems and not flipping through the checklist or pilot manual. More sophisticated models have a voice annunciation for the checklist, very cool.

written by EAI.

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