Flight without sight

Qinetiq has successfully tested technologies that it says will make light of a helicopter pilot’s work during adverse flying conditions.

Visibility can be greatly hindered at night, during inclement weather or low-level brown out (when visibility is obscured by wind and re-circulated dust). Qinetiq, however, claims its Day Night All Environment System is the solution.

A total of 40 night flying hours in simulated poor weather conditions enabled the team to verify the capabilities of technologies such as a head-tracking system and night-vision goggles (NVG) that incorporate a display and an advanced navigation system. The first demonstration of the combination of systems was carried out using a Sea King Mk IV-X helicopter at the Ministry of Defence’s Boscombe Down site.

‘We guided a pilot into a landing zone area and then he had to do a hover taxi about 25ft (7.6m) above the ground and fly around some obstacles before landing in a designated spot,’ said David Thorndycraft, a senior aircraft display systems specialist at Qinetiq.

‘We tested the system and found that he could complete the task using it. When he was using standard night-vision goggles he could not even get near the landing zone because of the obstructions we had put in his way.’

Qinetiq’s Day Night All Environment System is made up of imaging sensors, display systems and a guidance system.

Mounted on to the nose of the helicopter are a thermal imaging camera and another camera connected to a low-light TV, providing the pilot with different amounts of information over different wavebands. The fused image appears on a conventional colour, head-down display, while the information required by the pilot depends on his flight mode.

‘We used adaptive image fusion, which involves taking the output of the thermal imaging sensors and low-light TV and combining them in real time to present to the pilot the best attributes of each image. Low-light TV is an image-intensifier technology, similar to that used in night-vision goggles,’ said Thorndycraft.

‘The system knows what mode the pilot is in,’ he added. ‘For example, if the aircraft is close to the ground, the system is interested in texture cues from the outside world. It can also show the relative position of objects, so that you can judge your movement by the relative motion of one against the other.’

In addition to the sensors, the trial demonstrated a helmet-mounted display coupled with a mission-planner navigation system. A map-based system, the planner allows a pilot to enter a desired route on to a map. It then joins the points together and plans a safe route using knowledge of the local terrain.

‘Unfortunately, the system does not know whether that route is achievable given the speed that the helicopter wants to go at. But we have a system called Helicopter Terrain Following (HTF), which understands the dynamics of the aircraft and knows what its achievable limits are,’ said Thorndycraft. ‘So the route is passed through the HTF system and that generates a route that the aircraft will find more achievable. This results in a drastic reduction in the pilot’s workload.’

While the intensified images from the sensors appear on a head-down display, Qinetiq has also designed a NVG with a display fitted to it, which shows a symbolic picture to the pilot.

In addition to the usual information, such as speed, heading and height, the novel feature of the display is the ‘pathway in the sky’ symbology. ‘The pathway in the sky is a corridor of safety that is projected on to the pilot’s eyepiece and all he has to do is fly through a series of 3D boxes that defines the safe corridor,’ said Thorndycraft. This means the pilot will still be able to see where he needs to fly even if the real-world view is obscured, and a marker on the display shows where he is to land.

Finally, to land, the aircraft in the trial used a GPS system to locate the helicopter, combined with a magnetic head tracking system, which enabled the symbology to be projected accurately on to the display NVG, where the pilot was able to see it.

Although this capability has been demonstrated in simulation for many years, Thorndycraft said this trial was the first to test the head tracking and navigation system combination in a real aircraft.