Synthetic vision is an aviation display system that gives pilots a computer-generated view of the outside world. It shows terrain, obstacles, runways, horizon lines, and flight guidance even when clouds, darkness, or haze block the real view. This matters because many accidents happen when pilots lose awareness of their position relative to terrain or the runway.
A synthetic vision display acts like a virtual window, helping pilots understand the aircraft's situation quickly.
Understanding Aviation: Synthetic Vision
The display is built from several streams of data that must agree closely. A satellite navigation receiver estimates where the aircraft is. Inertial sensors measure turning, pitching, rolling, and acceleration.
Air data instruments measure pressure, airspeed, and altitude. The computer compares these inputs with a stored model of the land. It then draws the view from the aircraft's current direction of travel.
A small error in position or altitude can move a hill, runway, or guidance symbol on the screen. For this reason, certified systems continuously monitor their data sources and alert the crew when a source becomes unreliable.
The most important feature is not the realistic scenery. It is the relationship between symbols. The horizon line shows whether the aircraft is level, climbing, descending, or banked.
Flight path guidance shows where the aircraft is actually moving through the air. This can differ from where the nose points, especially in a crosswind. Runway boxes and pathway markers help the pilot judge alignment during an approach.
Terrain colors and alert shading draw attention to land that may be too close. Pilots learn to scan these features with the altitude, airspeed, heading, and navigation instruments. One picture supports the scan, but no single picture tells the whole story.
Approach and landing are common times to use synthetic vision. At night, a runway may be hard to see until the aircraft is close. In haze, distant terrain can blend into the sky.
In mountain areas, the ground may rise rapidly along a route. The display can make the planned path easier to understand before the outside view becomes clear. It is especially useful for maintaining awareness after an air traffic controller gives a new heading or a change in altitude.
A pilot still follows the published approach procedure, obeys minimum safe altitudes, and uses approved navigation equipment. The displayed runway image does not give permission to descend below a safe altitude.
Students should pay close attention to the difference between groundspeed and airspeed. Groundspeed is distance travelled over the ground divided by time. Wind can make groundspeed much higher or lower than airspeed.
This changes how quickly the aircraft reaches terrain or the runway. Descent planning depends on this timing. A three degree glide path is gentle, yet it loses roughly three hundred eighteen feet for each nautical mile travelled.
If groundspeed rises, the required rate of descent rises too. Another key idea is database currency.
A terrain model can be accurate while runway details or obstacles have changed in the real world. Pilots check updates, notices, and normal instruments because a clear computer image can still be incomplete or wrong.
Key Facts
- Synthetic vision combines aircraft position, attitude, heading, and a terrain database to draw a 3D view.
- Groundspeed formula: v = d/t, where v is speed, d is distance, and t is time.
- Descent angle can be estimated by tan(theta) = altitude loss / horizontal distance.
- A common glide path is about 3 degrees, which gives about 318 ft of descent per nautical mile.
- GPS position, inertial sensors, and air data help the system place the aircraft correctly in the virtual scene.
- Synthetic vision improves situational awareness but does not replace pilot judgment, instrument procedures, or visual requirements.
Vocabulary
- Synthetic Vision System
- A cockpit system that creates a 3D computer image of terrain, runways, and flight guidance using aircraft data and stored databases.
- Primary Flight Display
- The main cockpit screen that shows essential flight information such as attitude, altitude, airspeed, heading, and navigation cues.
- Terrain Database
- A stored digital map of ground elevations, obstacles, airports, and runways used to build the synthetic scene.
- Flight Path Vector
- A symbol on the display that shows where the aircraft is actually moving through the air.
- Situational Awareness
- A pilot's understanding of the aircraft's position, motion, environment, and possible hazards.
Common Mistakes to Avoid
- Treating synthetic vision as a live camera view is wrong because it is a computer drawing based on databases and sensor inputs, not a real-time optical image.
- Ignoring database currency is wrong because outdated terrain, obstacle, or runway data can make the displayed scene incomplete or misleading.
- Assuming the display proves the aircraft is safely clear of terrain is wrong because GPS errors, sensor faults, or database limits can still create risk.
- Confusing the flight path vector with the nose of the aircraft is wrong because the aircraft can point one way while wind and momentum carry it along a different path.
Practice Questions
- 1 An aircraft is 6 nautical miles from the runway threshold and is on a 3 degree glide path. Using 318 ft of descent per nautical mile, what approximate altitude above the runway should it be at?
- 2 A plane travels 24 nautical miles in 8 minutes while approaching an airport. What is its groundspeed in knots?
- 3 A pilot is flying at night in clouds and sees a runway and terrain on the synthetic vision display. Explain why this display improves situational awareness, and explain one reason the pilot must still follow instrument procedures.