Critical area

In aviation, a critical area refers to a designated area of an airport that all aircraft, vehicles, persons or physical obstructions must remain clear of when one or more Instrument Landing Systems (ILS) are in use, to protect against signal interference or attenuation that may lead to navigation errors, or accident. Critical areas also protect the ILS system's internal monitoring. In aviation, a critical area refers to a designated area of an airport that all aircraft, vehicles, persons or physical obstructions must remain clear of when one or more Instrument Landing Systems (ILS) are in use, to protect against signal interference or attenuation that may lead to navigation errors, or accident. Critical areas also protect the ILS system's internal monitoring. ILS technology delivers two main types of information to pilots. These types include the glideslope (vertical location relative to the designed glide path) and the localizer (lateral position relative to the designed approach course). Each type of information is broadcast using a separate antenna array and each type has a specific critical area: