• Garmin SVT showing colour-coded terrain warning.
    Garmin SVT showing colour-coded terrain warning.

No matter how much technology we build into aircraft cockpits, nothing will ever be better than looking out the window and seeing.

But there are days and nights when we just can’t do that and need other means of getting home safely.

Traditional IFR navigation has meant flying precise paths around high ground based on measurements from known points, either on the ground or in space.

Except for a few cases, this technique has proven efficient and safe, even though the pilots have had to trust the instruments and fly on blindly.

Now, synthetic visions (SV) systems are being introduced to GA aircraft that provide virtual VMC and give the pilot the ability to ‘see’ the terrain below, providing that extra bit of confidence in a critical approach.

Using sophisticated graphics modelling, SV recreates the landscape from a flight deck’s terrain-alerting database.

Pilots are shown a 3-D representation of ground and water features, airports, obstacles and traffic relative to the aircraft.

In most cases, the landscape is cast underneath the PFD and substitutes for the traditional blue/brown background.

SV also introduces a lot of other features that would otherwise not be possible, all designed to take the stress out of tricky approaches and reassure the flight crew the flight path is on track.

Regardless of which system you have installed, SV is not intended to replace approved IFR navigation instruments, but rather to augment them.

Chelton, a brand of Cobham Avionics, integrates SV with its standard FlightLogic EFIS (see ‘Flight Decks’), whereas it is an option for most competing systems.

The colouring follows the standard blue/brown background, but features that protrude above the horizon are shown as they really are, which means the horizon is not just a flat line.

Topography is overlaid with contour lines so valleys, ridges and plateaus are rendered in 3D.

Being derived from a GPS position and the EFIS database, artificial obstructions such as towers and buildings can also be depicted and therefore avoided.

Airports are also shown with clarity, which can help you locate the real thing visually.

With this level of accuracy, it is very easy to hand-fly the aircraft using SV to avoid the high ground.

Chelton has resisted enhancing the display with earth-like textures, providing only simple and effective contouring, which results in only the necessary information reaching the pilot’s eyes.

The display flow is smooth and devoid of pixilation or jerkiness in the turn, which would make accurate turns onto flight paths or localisers nearly impossible to get right first time.

One of the major features of SV is the highway-in-the-sky function.

A series of green boxes depicting an approach path or GPS flight plan path are shown on the PFD.

Each box represents the same size section of the sky.

Garmin SVT

Like just about everything Garmin gets their hands on, they have taken basic synthetic vision and supercharged it.

Their SVT (synthetic vision technology) has incredible depth of clarity, showing the terrain in rich contrasting textures that need no interpretation.

Certainly, the close relationship to what you would see out the window makes using SVT more instinctive.

The database is the same one that their TAWS uses, and like the TAWS, the SVT background is colour-coded to alert pilots potential flight-into-terrain risks.

The base background is the traditional brown, changing to amber for higher ground and red for features likely to be a problem.

Avoid the red ones and you are home free.

SVT can be integrated with TIS, TAS and TCAS.

The display uses standard TCAS symbols to alert the pilots to potential conflict and the symbol size increases as the traffic gets nearer, just like the real thing.

Garmin’s version of highway-in-the-sky is called pathway-in-the-sky (PITS).

It creates a 3D path on the PFD, showing en-route legs, terminal procedures, and ILS or GPS approaches by using a ‘tunnel’ of magenta boxes on the display.

At the time of writing, Garmin lists SVT as an option on only the G1000 EFIS.


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