Eurofighter ergonomics

---

BAE Systems looks to Direct Voice Input to address cockpit ergonomic concerns for the Eurofighter Typhoon.

by Stuart Birch, European Editor

The Eurofighter Typhoon second development aircraft.

Direct Voice Input (DVI) is likely to become an increasingly important aspect of military cockpit ergonomics in the future. "DVI is natural and intuitive," said Chris Smith, BAE Systems' Eurofighter Typhoon Enhanced Operations Capability Manager. "It is used extensively in the aircraft, and the teams involved in cockpit design believe it will become an integral way in which to manage the systems within the aircraft." While DVI is not likely to be used for the operation of safety-critical systems or for weapons release, Smith believes applications for it are likely to expand.

A four nation program—UK, Germany, Italy, and Spain (France dropped out to develop the Rafale)—the Typhoon has been a long time in the making. In the mid-1980s, BAE designed and flew the EAP (Experimental Aircraft Program) technology demonstrator, the general configuration of which pointed the way to the Eurofighter's design. Political developments, including the end of the Cold War and the resultant change in military requirements, have been contributory factors to the Typhoon's lengthy gestation period. First flight of the initial development aircraft, designated DA1, occurred at the European Aeronautic, Defense, and Space Co. (EADS) facility at Manching, Germany, in March 1994.

Cockpit ergonomics was always at the forefront of the design and development priorities of the aircraft, enabling it to adapt to multiple roles—BVR (beyond visual range) and close combat with what are described as "significant" ground attack capabilities—and to have export potential outside the four partners. The original Eurofighter specification called for a single-seat design, despite the likelihood of a high workload for the pilot. The decision was made based on the experience and input of the four partner nations; anticipated advances in technology and levels of automation indicated a single-seat cockpit was feasible. This concept has been proven, said Smith, a former RAF F4 Phantom and Tornado F3 navigator. "In the early phase of the aircraft's cockpit design, it was known that helmet-mounted displays (HMD) and other facilities would be available as the development program progressed. Although the days may have gone when it was deemed necessary for combat aircraft to have two crewmembers to cope with the high workload, there is a counter argument: that there is no such thing as a low-workload cockpit. Pilots are always given extra things to do," he said. "Basically, the cockpit of the Eurofighter Typhoon centers on the technology of the helmet, sensor fusion, and the displays that allow the pilot time to concentrate primarily on the mission rather than on flying the aircraft per se."

A hardened aircraft shelter contains the Eurofighter Typhoon.

The cockpit has not changed significantly in layout since its initial design a decade ago, although switch positions and moding have been modified. The cockpit is dominated by three 6-in-square active-matrix LCD full-color screens. The Eurofighter's cockpit is large, and the canopy is similarly long and wide, which allows high ambient light levels necessary to avoid screen washout. "We have developed a specific rig facility that can simulate environments from total blackness to sun over the pilot's shoulder directly on to the screen," said Smith. "Fast jet pilots are well aware that lighting needs to be a significant design driver in the creation of an ergonomically effective cockpit, and a great deal of effort has been put into ensuring that colors do not get washed out." Although Smith did not go into detail about the screens, he said that it is the quality of the color and the contrast between adjacent colors that provide the necessary levels. "For example," he said, "on digital maps, the colors normally used for shading contours are crucial to give an immediate indication of terrain. Our choice of colors and tones gives the pilot an instantaneous awareness of the terrain ahead of, and around, the aircraft."

As is usual with a glass cockpit, providing the pilot with on-screen information on a need-to-know basis for particular phases of flight can ease workload. "And of course the pilot is not told that everything is working—only if it is not," said Smith. "We use attention-getters, a warning system via voice, and a dedicated warning panel separate from the main screens and close to the pilot's right knee. The pilot can then call up a checklist on to one of the screens to run through necessary checks."

Eurofighter is aiming for a paperless cockpit. Although this is a requirement of the four partner nations, it currently remains necessary for Typhoon pilots to carry some books and checklists into the cockpit. "Nobody has a paperless cockpit yet because of the necessity to meet integrity requirements," said Smith. "But there is no reason why eventually everything cannot be put on screen. However, that will also call for a culture change, so it is not going to happen in the short term."

Smith said that as a former fast jet "back-seater," he has been surprised with the amount of work a single crewmember can achieve through technology. Pilots of the four partner nations have been constantly working together with designers, engineers, industry aircrew, and ergonomists on the layout of the Typhoon cockpit and the application of its systems, refining these via development rigs. Because particular focus was placed on the size and comfort of the Typhoon cockpit, pilots adapt to it quickly and easily. Partly because of cockpit space, it was decided to use a center stick rather than a sidestick controller. "Every military aircraft cockpit design has to be something of a compromise, but in a small cockpit, a center stick can cause particular ergonomic difficulties, perhaps limiting the size of the display area for the instruments and/or screens," Smith said. "That is when options are considered, and one of those would be the sidestick as used in the F-16. However, if the cockpit is sufficiently large and the geometry of the seating position is correct, there is no reason to have anything other than a center stick—and the pilots of the four partner nations agreed. The choice between center sticks and sidesticks is 40% personal—the balance being on technical grounds. We find that F-16 pilots convert easily and naturally to a center stick."

BAE Systems is investigating several technologies to improve ergonomics and pilot awareness in the Eurofighter Typhoon cockpit.

The extensive use of DVI in the aircraft is a significant part of the cockpit's ergonomic efficiency, according to Smith. It can be used for a wide variety of tasks, such as controlling head-down displays and organizing attack profiles. It can also be used to assign targets quickly to individual aircraft in a formation. In addition, changing displays via DVI is quick and straightforward, with the pilot's instruction repeated as text on the head-up display (HUD).

"Use of DVI tends to be in high-workload, but lower-dynamic situations," said Smith. "As a pilot enters the attack mode and experiences a rapidly changing situation, his or her actions tend to move toward stick and throttle, and under high-g situations, DVI would unlikely be used." Although every system function that can be performed via DVI must also have an equivalent physical operation, Smith said it is proving very reliable. "As a new system at the start of the 1990s, we achieved 85-90% recognition of sounds—not words; we always refer to sounds—but with the development of new algorithms to give a much higher recognition rate, the figure is now much higher." Aircrews tend to speak with slightly greater emphasis when airborne.

The Typhoon's HMD is also an important aspect of the aircraft's cockpit ergonomics. A complex display and cueing system, it provides flight reference data and weapon aiming functions. Flight information, including speed and altitude plus tactical information, is provided on the Helmet Mounted Symbology System. Using a series of head-tracking sensors, the Typhoon helmet presents all this information and more to the pilot wherever he or she may be looking. This effort enables the pilot to see the battle develop and to maintain "head out" awareness. Forward-looking infrared data can be projected to the HMD, as can the scene via the aircraft's night vision enhancement cameras. The helmet has a binocular, fully overlapped 40° field of view.

The financial price of advancing technology is always a concern, but economies of scale can be achieved both with regard to manufacturing and support costs, according to Smith. "In the early 1990s, many onboard computers were specific to task, but the closer we get to more common multifunction computers, the better economies of scale we will see," he said. "And there are huge efforts being made throughout the world to attain common avionics architecture. Also, in broad terms, the military is now moving away from defining pieces of equipment to defining capability; it is up to the aerospace industry to meet that capability at the right price."