TRAFFIC INFORMATION SERVICE

Traffic Information Service (TIS) provides many of the functions available in TCAS; but unlike TCAS, TIS is a ground-based service available to all aircraft equipped with Mode S transponders. TIS takes advantage of the Mode S data link to communicate collision avoidance information to aircraft. Information is presented to a pilot in a cockpit display that shows traffic within 5 nautical miles and a 1,200-foot altitude of other Mode S-equipped aircraft. The TIS system uses track reports provided by ground-based Mode S surveillance systems to retrieve traffic information. Because it is available to all Mode S transponders, TIS offers an inexpensive alternative to TCAS. The increasing availability of TIS makes collision avoidance technology more accessible to the general aviation community. Beginning in 2005, the use of Mode S TIS is being discontinued at some sites as the ground radar systems are upgraded. In all, 23 sites are expected to lose TIS capability by 2012.

TERRAIN AWARENESS AND WARNING SYSTEM

The Terrain Awareness and Warning System (TAWS) is an enhanced ground proximity warning capability being installed in many aircraft. TAWS uses position data from a navigation system, like GPS, and a digital terrain database to display surrounding terrain. TAWS equipment is mandatory for all U.S registered turbine powered airplanes with six or more passenger seats. FAA and NTSB studies have shown that a large majority of CFIT accidents could likely have been avoided had the aircraft been equipped with enhanced ground proximity warning systems.

GRAPHICAL WEATHER SERVICE

The Graphical Weather Service provides a graphical representation of weather information that is transmitted to aircraft and displayed on the cockpit display unit. The service is derived from ground-based Mode S sensors and offers information to all types of aircraft, regardless of the presence of on-board weather avoidance equipment. The general aviation community has been very pro-active in evaluating this technology, as they have already participated in field evaluations in Mode S stations across the U.S. The service is provided through one of two types of flight information services (FIS) systems. Broadcast only systems, called FIS-B, include a ground- or space-based transmitter, an aircraft receiver, and a portable or installed cockpit display device. They allow pilots to passively collect weather and other operational data and to display that data at the appropriate time. They can display graphical weather products such as radar composite/mosaic images, temporary flight restricted airspace and other NOTAMs. In addition to graphical weather products, they can also show textual information, such as Aviation Routine Weather Reports (METARs)/Aviation Selected Special Weather Reports (SPECIs) and Terminal Area Forecasts (TAFs).

Two-way FIS systems are request/reply systems, that is, they permit the pilot to make specific requests for weather and other operational information. An FIS service provider will then prepare a reply in response to that specific request and transmit the product to that specific aircraft for display in the cockpit.