How Air Traffic Control Works

Types of Flight

Just as there are rules of the road there are also rules for aircraft in the skies: Visual Flight Rules and Instrument Flight Rules.

The pilot chooses which to use, however for some types of airspace only aircraft flying on Instrument Flight Rules are allowed.

Some aircraft carry a minimum of instruments and equipment, such as ultralights. Others carry very advanced and sophisticated instrumentation, such as modern Boeing and Airbus passenger aircraft.

Visual Flight Rules:
Visual Flight Rules (VFR) are important for aircraft with little or no instrumentation. The rules rely on good visibility, so pilots can see what is flying around them. Therefore, this type of flying is very weather dependent.

Instrument Flight Rules:
Instrument Flight Rules (IFR) are used by jet aircraft, and most large commercial flights. Instrument flying uses sophisticated navigation equipment which allows the aircraft to fly in virtually all weather.

Class A airspace can only be flown by aircraft using Instrument Flight Rules.

For some types of airspace the type of service provided by ATC to aircraft flying on Instrument and Visual Flight Rules varies.