Human factors are important in the design of modern cockpits. The layout and function of cockpit displays and controls are designed to increase a pilot’s situation awareness without causing information overload. Instrument panels are now almost wholly replaced by electronic displays which are often re-configurable to save space. While some hard-wired dedicated switches must still be used for reasons of integrity and safety, many traditional controls are replaced by multi-function controls. Controls are incorporated onto the stick and throttle to enable the pilot to maintain a head-up and eyes-out position. The primary component of the glass cockpit is the Electronic Flight Instrument System (EFIS), which displays all information regarding the aircraft’s situation, position and progress. Comprising left-and-right-side primary flight display (PFD) and multi-function display (MFD) screens, EFIS primarily covers horizontal and vertical position, but also indicates time and speed. On the flight deck, the display units are the most obvious parts of an EFIS system, and are the features which give rise to the name “glass cockpit”. The display unit taking the place of the ADI is called the primary flight display. If a separate display replaces the HSI, it is called the navigation display (ND). The PFD displays all information critical to flight, including calibrated airspeed, altitude, heading, attitude, vertical speed and yaw. The PFD is designed to improve a pilot’s situational awareness by integrating this information into a single display instead of six different analog instruments, reducing the amount of time necessary to monitor the instruments. PFDs also increase situational awareness by alerting the aircrew to unusual or potentially hazardous conditions by changing the color or shape of the display or by providing audio alerts. The second part of the glass cockpit, comprising over-and-under center display screens, shows the aircraft’s systems conditions and engines performance. This is variously called EICAS (Engine Indications and Crew Alerting System) or ECAM (Electronic Centralised Aircraft Monitor), the former being the Boeing term and the latter Airbus’ acronym. All this information is graphically presented in a “need-to-know” basis, however, the pilot may query the system for further details of interest. In the cockpit, the EFIS has some unique advantages. EFIS offers versatility by avoiding some of the physical limitations of traditional instruments. Another advantage is that the flexibility afforded by software modifications minimizes costs when new aircraft equipment and new regulations are introduced. The EFIS system can be updated with new software to extend its capabilities. Such updates introduced in the 1990s included enhanced GPWS, and TCAS. Finally, a degree of redundancy is available even with the simple two-screen EFIS installation.