Terminology:

ATC: Air Traffic Control

Flying level 290(two niner-zero or two-nine-zero) elevation 29,000 feet

Level 350(Three-five-zero) evevation 35,000 feet

and so on...

ACARS: Aircraft Communications Addressing and Reporting System (ACARS) is a digital datalink system for transmission of short, relatively simple messages between aircraft and ground stations via radio or satellite.

Aircraft Guard Frequency:

The aircraft emergency frequency (also known as guard) is a frequency used on the aircraftradio band reserved for emergency communications for aircraft in distress. The frequencies are 121.5 MHz for civilian, also known as International Air Distress (IAD) and 243.0 MHz for military use, also known as Military Air Distress (MAD). Both are in use at the international level.

Transponder

A transponder (short-for transmitter-responder and sometimes abbreviated to XPDR, XPNDR, TPDR or TP) is an electronic device that produces a response when it receives a radio-frequency interrogation. Aircraft have transponders to assist in identifying them on radar and on other aircraft's collision avoidance systems.

Air traffic control units use the term "squawk" when they are assigning an aircraft a transponder code, e.g., "Squawk 7421". Squawk or squawking thus can be said to mean "select transponder code" or "I have selected transponder code xxxx".

ELT

Emergency Locator Transmitter

Distress radio beacons, also known as emergency beacons, ELT or EPIRB, aretracking transmitters which aid in the detection and location of boats, aircraft, and people in distress. Strictly, they are radiobeacons that interface with worldwide offered service of Cospas-Sarsat, the international satellite system for search and rescue (SAR). When manually activated, or automatically activated upon immersion, such beacons send out a distress signal. The signals are monitored worldwide and the location of the distress is detected by non-geostationary satellites, and can be located by trilateration in combination with triangulation respecting the varying quality of the signal received.

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 or GLONAS position can be encoded into the signal, which provides instantaneous identification of the registered user and its location. Frequently, by using the initial position provided via the satellite system, SAR aircraft and ground search parties can home in on the distress signals from the beacons and 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:

• 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 emergencyservices; e.g., 9-1-1. They are also used for crewsaving applications in shipping and lifeboats at terrestrial systems. In New South Wales, some police stations and the National Parks and Wildlife Service provide personal locator beacons to hikers for no charge