Aircraft Synthetic Vision Systems: What They Show and What They Cannot Replace

An aircraft synthetic vision system, or SVS, builds a computer-generated view from aircraft state and stored terrain, obstacle, runway and navigation data. It can make the relationship between the flight path and surrounding terrain easier to interpret, particularly at night or in instrument conditions.

The picture is still a model. It is not a live camera view, it can be wrong when an input or database is wrong, and it does not by itself give a pilot permission to descend below an instrument approach minimum.

This article replaces an earlier version that made unsupported claims about accident prevention, market adoption, equipment prices and manufacturer dominance. The useful pilot question is narrower: what information produced the picture, what approval applies to the installation, and what must still be cross-checked?

What synthetic vision actually displays

The FAA's active Advisory Circular 20-185A describes an SVS as an electronic means of displaying a synthetic vision image of the external scene. The image is typically assembled from several inputs:

• position from an approved navigation source;
• attitude and heading information;
• barometric or geometric altitude data;
• stored terrain, obstacle, airport and runway data; and
• display software that converts those inputs into the chosen perspective and symbology.

The resulting view can include terrain shading, a horizon, runways, flight-path information and other cues. The exact features and permitted uses depend on the installed equipment, its approval basis, the aircraft flight manual or supplement and the operator's procedures.

The system does not create an independent view merely because the image looks three-dimensional. A position error, attitude-source problem, altitude mismatch or database omission can move or distort what the pilot sees.

Synthetic vision is not enhanced vision

The terms are easy to mix together because both can present an outside-world scene on a flight-deck display.

System	Primary source of the picture	Core limitation
Synthetic vision system	Aircraft state plus stored terrain, obstacle and navigation data	It cannot show an unrecorded or newly changed object simply because that object is outside the aircraft
Enhanced vision system	A forward-looking imaging sensor, such as infrared or visible-light equipment	The sensor image is constrained by its field of view, range, weather response and installation
Combined vision system	Synthetic and enhanced information presented together	Approval and operational credit still depend on the exact system, presentation and rule

An enhanced flight vision system, or EFVS, is a defined regulatory concept with a real-time sensor image and specific display and operating requirements. A synthetic scene alone is not converted into an EFVS merely by appearing on a primary flight display.

That distinction matters when an equipment brochure mentions approach capability. The pilot has to identify whether the statement concerns situational awareness, an approved EFVS operation under 14 CFR 91.176, or another specifically approved function.

What SVS cannot replace on an instrument approach

The FAA's Aeronautical Information Manual states that a synthetic vision image is derived from aircraft attitude, a high-precision navigation solution and a database of terrain, obstacles and relevant cultural features. It is not produced by a real-time external sensor.

The AIM also draws the operational boundary: an SVS cannot be used instead of the natural vision required below decision altitude, decision height or minimum descent altitude. A pilot flying an approach therefore still has to comply with the published procedure, applicable minima, visibility rules and required visual references.

SVS can support orientation before that point. It does not make an unseen runway visible in the legal or sensor-derived sense, change the minimum altitude or validate that the actual environment matches every stored feature.

The failure paths are part of the picture

A vivid display can feel more direct than numbers and conventional symbols. That makes it important to understand the chain behind it.

Navigation and attitude inputs

The scene can be misplaced if the navigation solution is degraded or the wrong position source is selected. An attitude or heading fault can tilt or rotate the apparent world. Pilots should know the annunciations, comparator logic and reversion available in their installation.

Altitude reference

Terrain relationship can change when the system uses a different altitude source or reference from the one the pilot expects. Barometric-setting error, sensor error and geometric-altitude processing should not be treated as interchangeable without the installation documentation.

Database coverage and currency

Terrain and obstacle information has a defined source, resolution, coverage and update state. A temporary crane, a recent survey change or an object outside the database criteria may not appear. A runway depiction can also be affected by database or positioning error.

Display geometry

Field of view, minification, declutter and colour conventions influence how distance and closure appear. A compelling picture is not necessarily a scale representation of what a pilot would see through the windscreen.

Common-mode dependence

Two displays can show the same incorrect scene if they share the failed input or database. Duplication of the image does not always provide an independent cross-check.

Certification answers only part of the pilot's question

AC 20-185A provides FAA guidance for airworthiness approval of installed synthetic-vision guidance systems. It consolidates earlier SVS guidance and addresses intended functions, system performance, human factors, failure conditions and flight-test considerations.

An approved installation has been assessed for its stated functions and limitations. That does not establish that every SVS has the same features or operational authority. Nor does it turn a general display feature into a primary navigation source, terrain-warning system or approach credit unless those functions are separately approved.

The controlling evidence for a particular aircraft is therefore installation-specific:

1. the aircraft flight manual, supplement or other approved operating information;
2. the avionics pilot guide and current software configuration;
3. the navigation, terrain and obstacle database status;
4. placards, limitations and abnormal procedures; and
5. the operator's approved procedures and training, where applicable.

Product names are not approval labels. Two aircraft carrying similarly named displays can have different software, sensors, limitations and permitted uses.

Human-factors work remains current

The FAA's Civil Aerospace Medical Institute continues to examine how advanced flight-deck displays fit actual operations. Its 2026 operational and human-factors research addresses evaluation of display concepts in the context of pilot tasks rather than assuming that a more detailed image is automatically suitable.

The FAA also published an aircraft-flight-deck display evaluation aid in 2026. The framework directs attention to intended function, pilot interaction, workload, attention, training and operational suitability.

For an SVS user, that means training should go beyond recognising the normal terrain picture. It should include degraded or conflicting inputs, display failure, database limitations, unusual attitudes, go-around decisions and reversion to the approved underlying instruments.

A practical pilot checklist

Before relying on an SVS presentation, ask:

1. What is the approved function of this installation?
2. Which sensors and databases create the image?
3. How are position, attitude, altitude or database faults annunciated?
4. What terrain, obstacle and runway-data limitations apply?
5. Which other instruments or alerts provide an independent cross-check?
6. What changes when the display, navigation source or attitude source fails?
7. Does any claimed approach credit actually apply to SVS, or to a separately approved EFVS function?
8. When were abnormal and reversion procedures last practised?

The basic discipline remains unchanged: fly the approved procedure, monitor the primary flight and navigation information, respect terrain and obstacle alerts, and use the synthetic image within the documented limits.

The 2026 bottom line

Synthetic vision can provide a useful, intuitive depiction of terrain, obstacles and the planned flight environment. Its value comes from presenting several approved data sources in a form a pilot can interpret quickly.

Its limit is equally important. The display is database-derived, not a live confirmation of the world outside. It does not replace required natural vision below approach minima, and it should not displace the underlying instruments, alerts, procedures or pilot cross-check.

Sources reviewed

• FAA Advisory Circular 20-185A: Airworthiness Approval of Installed Synthetic Vision Guidance Systems
• FAA Aeronautical Information Manual, section 5-4
• 14 CFR 91.176: EFVS operations
• FAA 2026 operational and human-factors research
• FAA 2026 aircraft-flight-deck display evaluation aid