Nowadays all flights operate under VFR (Visual Flight Rules) or IFR (Instrument Flight Rules). A VFR pilot is qualified and authorized to fly only in good weather conditions and is responsible for maintaining separation from other aircraft and obstructions on the basis of what he / she can see. An IFR pilot is permitted to fly in all weather conditions, when visibility may be low, and relies on flight instruments and navigational aids to follow a safe course. Most IFR flights take place in controlled airspace where air traffic control services issue instructions to pilots to ensure the safe and efficient flow of traffic. When you board a commercial flight, it is probably flying under IFR, but if a friend or relative offers to take you up in an airplane around your local area on a sunny day, then this is most likely flying under VFR.
Basic navigation (VFR navigation)
In the early days of flight, navigational aids did not exist and the basic technique followed was pilotage. Flights were at low altitude and the pilot simply looked out the window and navigated with reference to known landmarks. In some cases, it was just a question of following a road, river or railway to the desired destination. While a VFR pilot today will still use this technique, there is an obvious danger of getting lost, particularly if bad weather sets in suddenly. VFR pilots are nowadays advised to plan their flight carefully before taking off using the detailed aeronautical charts they have at their disposal. They plan their route, taking into account natural obstacles and airspace which may be restricted or controlled (they will either need prior authorization to enter or it may not be open to them at all). They then mark this route on their charts.
For all aircraft, and light aircraft in particular, wind is an impotant factor in flight planning. A pilot who tries to fly along a planned route risks being blown off course unless a suitable heading is chosen based upon meteorological forecasts of wind strength and direction. The chosen heading will probably need to be altered in flight in response to changes in the strength or direction of the wind. Note that the word track is also used to refer to the actual route taken by the pilot when, as frequently happens, the flight plan changes.
A heading is expressed in degrees with magnetic north as a reference, it should not be confused with the term bearing, also expressed in degrees, where an alternative reference is explicitly stated (e.g. a particular beacon). For example a pilot may be heading due west (a heading of 270°) having just passed directly over a beacon, in which case the pilot has a bearing of 180° in relation to this beacon.
A technique known as dead reckoning serves as a check that all is going to plan. The pilot selects some easily recognizable landmarks along the planned route and calculates how long it will take to reach these points taking into account both the planned airspeed and wind. These points are known as checkpoints, and when the planned time has elapsed the pilot expects to identify the landmarks on the ground. When this happens he / she has made a fix and can confidently proceed with the next stage along the planned route.
The magnetic compass is the basic navigational aid that a VFR pilot will use.
Despite all their training and the existing regulations, VFR pilots do get lost from time to time, fly into airspace that they shouldn't normally be flying in, or find themselves in IMC (Instrument Meteorological Conditions), such as flying through cloud, for which they are not necessarily equipped or trained. The consequences are potentially very serious and it often falls to the highly skilled air traffic controllers or perhaps to other more experienced pilots who are flying in the vicinity to do what they can to help.
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