How Do Aircrafts Communicate With Each Other?

Aircraft communication is key for pilots as the utilization of global airways continues to grow. Generally speaking, aircraft fly at an altitude of 35,000 to 42,000 feet and must be able to maintain regular contact with other aircraft, control towers, and their home base.

The level of communication capability is entirely reliant on a couple little sticklers extending from the airframe called communications antennas. At any given time, a commercial aircraft will have around 8 of these antennas equipped to its airframe.

A communications antenna is accessed by onboard radio equipment. This equipment is entirely reliant on the frequency band emitted by its associated antenna. The required application of the antenna will determine its size, location on the airframe, and frequency. The average antenna has a power transmitter between 7 and 16 watts. Communications antennas must maintain omnidirectional transmission, or equal radiation transmission in a spherical pattern where the antenna acts as the origin.

Communication via these devices is normally used to navigate to a destination safely. An aircraft is equipped with three types of antennas to ensure efficient coverage over a variety of frequencies. These are the short-range, long-range, and vertical fin antenna.

Short range antennas operate at a very high frequency (VHF) between 118MHz and 137MHz. Equipped with omnidirectional transmission and secured in an upright position, these antennas are ideal for communication with air traffic control. Their coverage potential has line of sight capacity— meaning range reaches the visible horizon, not including the curvature of Earth’s surface. A short-range antenna system is not capable of long-range direct communication, which brings up our next categorization.

Long range antennas provide reliable communication across an expansive distance. Commercial airliners resort to LHR’s in order to keep aircraft in touch with their home base, and as of the last decade, to provide Wi-Fi to passengers. An LHR system relies on a high frequency band of 3 - 30 MHz.

Vertical fin antennas are the most elusive of the three models. An antenna system runs from a wingtip to the tail of the aircraft. This configuration is utilized when an aircraft enters transnational airspace. As airplanes exit and re-enter certain VHF frequencies, they need to be able to quickly transfer to an available frequency band. Vertical fin antennas provide this necessity.