Definition
A situation in which a pilot operating under Visual Flight Rules continues flight into weather conditions that no longer permit visual reference to the ground or horizon, and that legally require flight by reference to instruments. It is one of the most lethal categories of general aviation accident, typically resulting from continued VFR flight into deteriorating weather such as cloud, fog, heavy precipitation, or low visibility.
Plain English
A pilot who is flying by looking outside flies into cloud or weather thick enough that they can no longer see where they are going, and now have to fly using only their cockpit instruments — something they may not be trained or current to do.
Context Anchor
Seen in weather decision-making, accident prevention, and aeronautical decision-making discussions, especially when reviewing whether to continue, turn around, divert, or land before conditions worsen.
Why Pilots Care
This situation is a leading cause of fatal weather-related accidents due to loss of visual references and spatial disorientation.
Grounding Statement
The key idea is simple: the flight started with outside visual references, but the weather removed those references.
Intuition Check
Do not read this as just “VFR near bad weather.” VFR into IMC means the aircraft has actually entered conditions where visual flying is no longer enough.
Example Sentence 1
The accident report concluded that the pilot continued VFR into IMC after the cloud base lowered below the surrounding terrain.
Example Sentence 2
Instructors stress that recognizing the first signs of deteriorating weather prevents VFR into IMC.