Technology & Planning

Aeroplane Cessna 303

Cessna 303

Max. duration of flight employment = 6 hours per day, max. flight altitude = 7,000 meters, speed = 140 knots. This plane has been used by Terra Bildmessflug since 1995. It was modified for aerial surveys and is capable of carrying various sensors and capture systems.

Digital camera Vexcel UltraCam Eagle Mark2 f100

Sensor Unit

Vexcel UltraCam Eagle Mark2 f100 with 340 Megapixels. High productivity and precise geometry.

Flight planning with TopoFlight


For planning our flight campaigns we use the professional planning software Topoflight. All flights are planned with an integrated digital terrain model. This allows a precise plan and ensures that all required flight parameters are met. Our vast experience in executing highly complex aerial surveys in mountainous areas paired with precise planning makes us a reliant partner for your (alpine) survey. For all customers we offer precise flight planning already in the offer phase. This ensures a good predictability and enables a more efficient project planning for the customer.

Flight missions preparation


Weather forecasts are continually monitored and checked. Before takeoff in the morning, the weather situation is finally evaluated and suitable flight regions are chosen for that particular day. If necessary, air-traffic control and – in some cases – the military authorities are contacted. Principally, flight clearance has to be applied for in advance. This applies to flights exceeding 3,000 meters altitude, flights in military restricted areas or in the vicinity of airports, and flights over habitat preservation areas. Prior to the flight mission, air-traffic control authorities are provided with the corresponding company-, project- and route-planning data.

Flight missions realization


Routine checks on the general condition of the aeroplane, fuel supply and security system are performed – then we are ready for takeoff. During the flight, constant contact to the air-traffic control is maintained, and our position can be monitored continuously. Once having entered the region in question, all systems are activated and the first corridor is entered into the navigation system (after a few test shots for finding the best suited illumination and aperture settings). Now the pilot has to follow the route guidance delivered by the flight-management system accurately to ensure that the photographs are automatically taken at the right positions. It is crucial that the aeroplane is kept exactly within the corridor (max. tolerance 30 – 50 meters) – both in planimetry and altimetry.

Prior to general GPS availability the navigator had to operate the telescope manually, and the pictures were also taken by hand. After the flight the films were taken out of the cassettes and immediately sent to the laboratory, complete with all the necessary instructions.

Aerial photography


During the flight, the camera operator constantly checks the photographing process. Technical system problems are immediately shown on a computer screen, thus exposure factors can be corrected at once.

The navigation telescope is still an irreplaceable tool for quality control: clouds, haze, flooding and fog can be identified in time. Countermeasures can be implemented straightaway. A flight corridor can be repeated during the same flight, should the weather conditions clear up.

Download and processing of the images

The aerial photographic material is downloaded from transportable data units in the airplane. This requires an extremely efficient hardware system, capable of securely transferring approximately 6,000 pictures to a local storage medium and a data transport unit overnight.

The transport units are sent to the office via courier and are copied on the high performance storage. Data processing from level 0 to level 3 starts immediately.