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An electronic flight instrument system, or EFIS, is a flight deck instrument display system in which the display
technology used is electronic rather than electromechanical. EFIS normally consists of a primary flight display
(PFD), multi-function display (MFD) and Engine Indicating and Crew Alerting System (EICAS) display. Although
cathode ray tube (CRT) displays were used at first, liquid crystal displays (LCD) are now more common.
EFIS--The complex electromechanical attitude director indicator (ADI) and horizontal situation indicator (HSI)
were the first candidates for replacement by EFIS. However, there are now few flight deck instruments for which
no electronic display is available. ELT--Distress radio beacons, also known as emergency beacons, are tracking
transmitters which aid in the detection and location of boats, aircraft, and people in distress. Strictly, they are
radiobeacons that interface with Cospas-Sarsat, the international satellite system for search and rescue (SAR).
When activated, such beacons send out a distress signal that, when detected by non-geostationary satellites,
can be located by triangulation.[citation needed] In the case of 406 MHz beacons which transmit digital signals,
the beacons can be uniquely identified almost instantly (via GEOSAR), and furthermore, a GPS position can be
encoded into the signal (thus providing both instantaneous identification and position). Often using the initial
position provided via the satellite system, the distress signals from the beacons can be homed by SAR aircraft
and ground search parties who can in turn come to the aid of the concerned boat, aircraft, or people. There are
three types of distress radio beacons compatible with the Cospas-Sarsat system:[1] EPIRBs (emergency
position-indicating radio beacons) signal maritime distress. ELTs (emergency locator transmitters) signal aircraft
distress.
PLBs (personal locator beacons) are for personal use and are intended to indicate a person in distress who is
away from normal emergency services, e.g., 9-1-1. They are also used for crewsaving applications in shipping
and lifeboats at terrestrial systems. |
