Aircraft vision systems help present the outside environment when the unaided view is difficult to interpret. Some sense the scene; some construct it from a database and aircraft state; some combine both. The first question is where each visible feature comes from.
Identify the source of the view
On a narrow screen, scroll the table horizontally. Keyboard users can focus the table region and use the arrow keys.
| System or feature | Source of the image | Main interpretation question |
|---|---|---|
| Enhanced vision (EVS) | Imaging sensors observe the external scene. | What can this sensor distinguish in these conditions? |
| Synthetic vision (SVS) | A database and aircraft position, attitude and altitude generate a view. | Are the source data and aircraft state suitable and current? |
| Combined vision (CVS) | Enhanced and synthetic information appear together. | Can the pilot distinguish the inputs and recognize disagreement? |
| Enhanced flight vision (EFVS) | An installed system integrates sensing, display and required flight information. | Which operation is approved for this installation and crew? |
The FAA's AC 20-167B explains EVS, EFVS and CVS and identifies synthetic vision as a database-derived presentation. The table is an introductory comparison; the FAA terms and approvals apply within U.S. civil aviation. Military systems have their own applicable authorities and requirements.
Each sensor responds to a different scene
A low-light camera relies on optical information available in its spectral band. Infrared imaging can reveal contrast that is weak in visible light. Radar-derived imagery measures another aspect of the environment. Combining sensors can provide complementary information, while adding alignment and timing questions.
Weather and obscurants affect different bands differently. Assess the actual sensor, the material in the viewing path and the conditions of the supporting test. A claim covering fog, dust, smoke and darkness needs evidence for those separate conditions. A successful demonstration through one obscurant establishes that demonstration.
The night-vision guide explains intensification, thermal imaging and overlays. It also explains why display color alone tells you little about the sensing method.
A clear synthetic view still depends on data
Synthetic vision can depict terrain even when the outside view is obscured, because it renders stored information from an estimated aircraft viewpoint. That makes the quality of the database, position and attitude inputs consequential. The display's visual clarity is separate from the completeness of the underlying information.
For technical background on database-derived systems, the FAA maintains separate synthetic-vision installation guidance in AC 20-185A. Evaluating an actual installation requires its approved documentation.
Separate an improved view from permission to use it
In U.S. civil aviation, operational credit for EFVS depends on the applicable rule, installation, equipment, pilot qualifications and authorization. The FAA EFVS resource page links the regulations, advisory material, training references and current notices. It is the appropriate starting point for checking changing requirements.
Three milestones deserve different labels: a research demonstration shows a result; airworthiness approval addresses an installation; operational authorization addresses a defined use. An article or video showing a visible runway supplies none of the missing approval documents.
One concrete issue in the FAA's current material is the interaction between infrared-based EFVS and LED airport lighting. The EFVS pilot training reference explains that an infrared-only sensor may be unable to image LED lighting whose output is outside its sensed band. “Visible to a person” and “visible to this sensor” can therefore differ.
Questions that make a vision-system claim useful
- Name the inputs. Identify which details come from sensors, databases or flight instruments.
- State the conditions. Record light, weather, motion and the features being evaluated.
- Identify the integration. Ask about image alignment, timing and how disagreement or missing data is indicated.
- Classify the evidence. Distinguish test results, installation approval and operational authorization.
- Keep the scope. Carry the equipment model, software baseline, date and jurisdiction into your summary.
These questions help readers assess aviation technology. Flight planning, training and operation require the approved manuals and responsible authorities for the actual aircraft. For another use of infrared sensing, see IRST on airborne platforms.