INSTRUMENTAL FLIGHT RULES
WHAT'S IFR ?
IFR means Instrument Flight Rules. It's a type of flight in which the pilot must be able to fly the aircraft in reference to his instruments only. He must be able to navigate and know his position only by using instruments. It's the reason why aircraft flying through bad weather conditions are most likely to file an IFR flight plan. They can't see outside the window. This doesn't mean that an IFR aircraft cannot fly in good weather conditions. In fact, most commercial airplanes are flying IFR all the time, even in good weather. However, pilot must use instruments to navigate. Separation from other aircraft is managed by ATC, most of the time. But again, it all depends of the class of airspace the aircraft is in.
IFR flights must be cruising at appropriate altitudes according to their direction of flight (westbound: even altitude, eastbound: odd altitudes, northbound: even, southbound: odd), at a thousand feet interval, starting at 1000 feet.
It is prohibited to fly above cities at less then 100 feet AGL. It is mandatory to always fly at 500 feet or above from ground. These rules don't apply for special flights (police, etc.) as well as during takeoff / landing phases of flight
SEPERATION AND CLEARANCE
The distance by which an aircraft avoids obstacles or other aircraft is termed separation. The most important concept of IFR flying is that separation is maintained regardless of weather conditions. In controlled airspace, Air Traffic Control (ATC) separates IFR aircraft from obstacles and other aircraft using a flight clearance based on route, time, distance, speed, and altitude. Despite the protection offered by flight in controlled airspace under IFR, the ultimate responsibility for the safety of the aircraft rests with the pilot in command, who can refuse clearances.
VISUAL FLIGHT RULES
VFR means Visual Flight Rules. It's a flight in which the pilot must be able to fly the aircraft by looking outside the windows using visual references. Pilot must be able to know where he is and must be able to see other aircraft in the vicinity, avoid them, and also avoid terrain and obstacles.
VFR flights above 3 000 feet must be flown at appropriate altitude depending on direction of flight (westbound: even altitudes, eastbound: odd altitudes), at each thousand feet, starting at 3 500 feet.
It is prohibited to fly VFR above cities at less then 1000 feet AGL. It is mandatory to always fly at 500 feet or above from ground. These rules don't apply for special flights (police, etc.) as well as during takeoff / landing phases of flight.
Filing a flight plan is a mandatory procedure on IVAO for all VFR flights, even when doing circuits. In the Route section, you can put visual points, or even IFR beacons (VORs, NDBs,..). It is permitted for a VFR pilot to fly airways or IFR beacons to other IFR beacons. It is permitted for VFR pilots to use instruments to navigate. The difference is that they must not depend on it.