What is IFF?
IFF stands for Identification Friend or Foe. It is a system intended to identify planes and vehicles whether they are literally allies or enemies of a particular state or country. In the case of an aircraft flying over US airspace for example, this particular aircraft can easily be identified and can also be interrogated with its mission or intentions. Through the IFF system, a control center for airplanes will be able to identify, communicate and/or interrogate any plane flying through a designated air space.
The IFF system is widely used by the US military. Modern IFF systems today works through two channels. One channel is dedicated for outgoing or interrogation type of signals. The other channel meanwhile is for the reply signal. Both these channels are also divided into four modes. Two modes are said to be shared by civilian and military airplanes. The remaining two modes are intended for military use only. All modes of the IFF have specific functions. In the case of military use, one mode takes care of identifying a particular aircraft and its supposed mission. Other modes may also be used to know the type of aircraft flying on a monitored airspace.
In the case of civilian use, FAA regulations stipulate that all airplanes have IFF systems. One mode under the IFF transponder system is designed for control of air traffic in airports for example. Aside from this particular mode, there is also another mode which functions automatically and reports the aircraft altitude.
The IFF system continues to play an important role in the field of aviation today. This applies to both military and civilian use. In the case of the military, security and surveillance is provided by the IFF system. In the civilian application meanwhile, IFF systems are necessary for air traffic control and also contribute to security in monitored air spaces.