Flight Rules
Flight rules are the rules, regulations & procedures used by aircraft flying in various conditions. The most common include:
- VFR (Visual Flight Rules)
- IFR (Instrument Flight Rules)
VFR
VFR stands for 'Visual Flight Rules', and as the name infers, this means flying using visual references. This can be a very simple method of navigation, though it requires Visual Meteorological Conditions (VMC).
Unless given a clearance by ATC, VFR aircraft should not depart from or arrive to an aerodrome when the cloud ceiling is less than 1500ft AGL or ground visibility is less than 5km.
Weather conditions can be found in METARs (See meteorology for more details.)
If these minima are not met, then the conditions are considered Instrument Meterological Conditions (IMC), and flights are required to operate under IFR. VFR also requires the pilot to see and avoid obstacles, such as terrain or other aircraft; pilots are responsible for seperation with other aircraft. Though the pilot is responsible for separation, Air Traffic Control may require the use of a transponder to identify the aircraft and provide seperation from IFR aircraft (see below). If an aircraft is planning to arrive at an airport in IMC using VFR, this aircraft will be denied clearance, and will have to divert or declare an emergency.
Note
VFR flights cannot operate in 'Class A' airspace, as this requires the pilot to be flying IFR, though may be entered if an emergency is decleared, or if a pilot is avoiding severe weather formations.
Note
Helicopters rarely use IFR, instead opting for a version of VFR, due to the unique operating characteristics of rotary-wing aircraft.
IFR
IFR stands for 'Instrument Flight Rules', where instruments are used rather than visual references. This tends to be more complicated than VFR, and visibility becomes less of a limiting factor. Often, the aircraft's capabilities define limitations; for example, not all airplanes have highly accurate INS systems. As IFR flights can take place in any weather, separation is managed by Air Traffic Control, as obstacle avoidance is no longer the pilot's responsibility.
As IFR flights do not use Visual References, they use navigational aids, such as VORs, NDBs, and GPS/GNSS. Air Traffic Control can also provide vectors to offer shortcuts, deconflict traffic, and more.
ATC
BAW134 Fly heading Zero Seven Zero.
IFR flights are generally given Pre-Departure Clearances by Air Traffic Control before departure. This can include:
- Standard Instrument Departure (SID)
- Squawk code
- Initial altitude
Note
A Pre-Departure Clearance is not typically required while flying combat missions, and instead the pilot should request taxi on initial contact, however, you should always check the relevant documents to confirm this.
A pilot wishing to fly IFR should have an aircraft equipped with the required equipment, and access to IFR charts, which contain airways, approaches, airfield published procedures and more. The required instruments include:
- Heading indicator
- Adjustable altimeter
- Chronometer (Stopwatch)
- Attitude indicator
- 2 Way Radios