Date: Tue, 10 Dec 1996 14:20:39 GMT Server: NCSA/1.4.2 Content-type: text/html Last-modified: Mon, 26 Feb 1996 05:46:35 GMT Content-length: 4911
After many years of extensive analysis, development, and flight evaluation by the Federal Aviation Administration and the aviation industry, a solution is available to the problem of reducing the risk of midair collisions between aircraft. This solution is known as the Traffic Alert and Collision Avoidance System (TCAS).
TCAS is a family of airborne devices that function independently of the ground-based air traffic control (ATC) system, and provide collision avoidance protection for a borad spectrum of aircraft types.
TCAS I provides proximity warning only, to assist the pilot in the visual acquisition of intruder aircraft. It is intended for use by smaller commuter aircraft and by general aviation aircraft.
TCAS II provides traffic advisories and resolution advisories (recommended escape maneuvers) in a vertical direction to avoid conflicting traffic. Airline aircraft, and larger commuter and business aircraft, use TCAS II equipment.
TCAS III, which is still under development, will provide traffic advisories and resolution advisories in the horizontal as well as the vertical direction to avoid conflicting traffic.
The TCAS concept makes use of the radar beacon transponders routinely carried by aircraft for ground ATC purposes. The level of protection provided by TCAS equipment depends on the type of transponder the target aircraft is carrying. It should be noted that TCAS provides no protection against aircraft that do not have an operating transponder.
PROCESS No_weaken_test; IF (WL.STATUS NE $NEW) THEN IF (ITF.REVERSE EQ $TRUE) THEN NOWEAKEN_TIME = P.TRVSNOWEAK; ELSE NOWEAKEN_TIME = P.TNOWEAK; IF (EVAL(TF.PERMTENT) LE EVAL(OWNTENT)) THEN IF (ITF.TAUR GT MAX(P.STROFIR, P.FRTHR(ITF.LEV,ITF.IFIRM)) THEN OWNTENT = TF.PERMTENT; ELSEIF (TF.PERMTENT(4,5) EQ '10') THEN CALL CHECK_PROJECTION IN (ITF.RZ, G.ALIM, OWNTENT) OUT (INTHR); IF (INTHR EQ $TRUE) THEN OWNTENT = TF.PERMTENT; ELSE IF ((G.TCUR-ITF.TCMD) LT NOWEAKEN_TIME OR ITF.IFIRM LT P.MINFIRM) THEN OWNTENT = TF.PERMTENT; OTHERWISE IF ((G.TCUR-ITF.TCMD) LT NOWEAKEN_TIME OR ITF.IFIRM LT P.MINFIRM) THEN OWNTENT = TF.PERMTENT; END No_weaken_test;