Azerbaijan Airlines National Aviation Academy Faculty: Air transport Group: 1139aa theme: tcas teacher: Sevda Aliyeva Student: Fariz Safarli

Azerbaijan Airlines
National Aviation Academy
Faculty: Air transport
Group: 1139aA
Theme: TCAS
Teacher: Sevda Aliyeva
Student: Fariz Safarli
As safety is paramount in all aviation, numerous measures are taken to keep aircraft separate from each other in the air. One such example is the collision avoidance system known as TCAS. But what exactly is it and how does it work?
TCAS stands for Traffic Collision Avoidance System and its purpose is to minimize the risk of mid-air collisions between aircraft. ICAO requires that all aircraft with a passenger capacity of more than 19 be equipped with this safety measure. The rule also applies to aircraft with a maximum take-off weight (MTOW) of more than 5,700 kg.
Operating independently of air traffic control, TCAS uses transponder signals from nearby aircraft to alert pilots of a potential midair collision. It does this by constructing a three-dimensional map of the airspace through which the aircraft passes. When detecting transponder signals from other aircraft, it can anticipate potential collisions based on the speed and altitude of the aircraft passing through the airspace in question.
If TCAS detects a potential collision, it will automatically alert each affected aircraft. In this case, it will automatically start a mutual avoidance maneuver. This includes a system of notifying the crews of the aircraft in question both audibly and visually to take off or land in such a way as to ensure that they do not meet when they cross paths.
TCAS provides communication between all aircraft equipped with the appropriate transponder (if the transponder is enabled and configured correctly). Each TCAS-equipped aircraft interrogates all other aircraft within a certain range (via 1030 MHz radio frequency) about its position, and all aircraft respond to the inquiries (via 1090 MHz). This polling cycle can happen several times per second.
The TCAS system creates a three-dimensional map of aircraft in the airspace, including their range, altitude, and bearing (with a homing antenna). It then extrapolates the current range and altitude difference to expected future values to determine whether a potential collision hazard exists.
The next step beyond identifying potential collisions is the automatic negotiation of mutual evasive maneuvers (maneuvers currently limited to changes in altitude and modification of climb/descent speeds) between two (or more) conflicting aircraft. These evasive maneuvers are communicated to the flight crew via the cockpit display and synthesized voice instructions.
Protected airspace covers every TCAS-equipped aircraft. The size of the protected volume depends on the height, speed and direction of the aircraft involved in the encounter. The following illustration provides an example of a typical TCAS protection scope.
Antennas
The antennas used by TCAS include a directional antenna mounted on top of the aircraft and an omnidirectional or directional antenna mounted on the underside of the aircraft. A Mode S transponder requires two antennas in addition to the two TCAS antennas.
One antenna is mounted on the top of the aircraft and the other on the bottom. These antennas allow the Mode S transponder to receive requests on the 1030 MHz frequency and respond to requests received on the 1090 MHz frequency.
Displays
The TCAS interface is shown with two displays: the PFD and the ND display. The ND display shows TCAS course and deviations, and the PFD display shows course and deviation steering commands. Standards for both the PFD and ND display are set forth in DO-185A.