In a composite aircraft, fiberglass is an excellent electrical  insulator, while carbon fiber conducts electricity, but not  as easily as aluminum. Therefore, additional electrical  conductivity needs to be added to the outside layer of  composite skin. This is done typically with fine metal meshes  bonded to the skin surfaces. Aluminum and copper mesh  are the two most common types, with aluminum used on  fiberglass and copper on carbon fiber. Any structural repairs  on lightning-strike protected areas must also include the mesh  as well as the underlying structure.  For composite aircraft with internal radio antennas, there  must be “windows” in the lightning strike mesh in the area  of the antenna. Internal radio antennas may be found in  fiberglass composites because fiberglass is transparent to  radio frequencies, where carbon fiber is not.  In the decades since World War II, composites have earned  an important role in aircraft structure design. Their design  flexibility and corrosion resistance, as well as the high  strength-to-weight ratios possible, will undoubtedly continue  to lead to more innovative aircraft designs in the future.  From the Cirrus SR-20 to the Boeing 787, it is obvious that  composites have found a home in aircraft construction and  are here to stay.  [Figure 3-17]  Until recently, most GA aircraft were equipped with  individual instruments utilized collectively to safely operate  and maneuver the aircraft. With the release of the electronic  flight display (EFD) system, conventional instruments have  been replaced by multiple liquid crystal display (LCD)  screens. The first screen is installed in front of the pilot  position and is referred to as the primary flight display (PFD).  The second screen, positioned approximately in the center  of the instrument panel, is referred to as the multi-function  display (MFD). These two screens de-clutter instrument  panels while increasing safety. This has been accomplished  through the utilization of solid state instruments that have  a failure rate far less than those of conventional analog  instrumentation.  [Figure 3-18]  With today’s improvements in avionics and the introduction  of EFDs, pilots at any level of experience need an astute  knowledge of the onboard flight control systems, as well as  an understanding of how automation melds with aeronautical  decision-making (ADM). These subjects are covered in detail  in Chapter 2, Aeronautical Decision-Making.  Whether an aircraft has analog or digital (glass) instruments,  the instrumentation falls into three different categories:  performance, control, and navigation.  The performance instruments indicate the aircraft’s actual  performance. Performance is determined by reference to the  altimeter, airspeed or vertical speed indicator (VSI), heading  indicator, and turn-and-slip indicator. The performance  instruments directly reflect the performance the aircraft  is achieving. The speed of the aircraft can be referenced  on the airspeed indicator. The altitude can be referenced  on the altimeter. The aircraft’s climb performance can be  determined by referencing the VSI. Other performance  instruments available are the heading indicator, angle of  attack indicator, and the slip-skid indicator.  [Figure 3-19]  Figure 3-17.  Composite materials in aircraft, such as Columbia 350  (top), Boeing 787 (middle), and a Coast Guard HH-65 (bottom).  Performance Instruments  Instrumentation: Moving into the Future  The Future of Composites  3-12 