In aviation, instrument flight rules (IFR) is one of two sets of regulations governing all aspects of civil aviation aircraft operations; the other is visual flight rules (VFR).
IFR in between cloud layers in a Cessna 172
IFR flying with clouds below
Aviation includes the activities surrounding mechanical flight and the aircraft industry. Aircraft includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air craft such as hot air balloons and airships.
A Boeing 747
LZ 129 Hindenburg at Lakehurst Naval Air Station, 1936
Lilienthal in mid-flight, Berlin c. 1895
First powered and controlled flight by the Wright brothers, December 17, 1903