What is the minimum altitude at which an aircraft must transition to VFR conditions unless otherwise specified?

The minimum altitude at which an aircraft must transition to Visual Flight Rules (VFR) conditions is 18,000 feet Mean Sea Level (MSL). At this altitude, aircraft are generally expected to operate under VFR, as the airspace becomes more structured with increasing altitude. Transitioning to VFR allows pilots to navigate visually and utilize their own judgment in flight operations as opposed to being in Instrument Flight Rules (IFR), which require aircraft to rely on instruments for navigation due to poor visibility or weather conditions.

This altitude defined for VFR operation aligns with the transition to class A airspace, which begins at 18,000 feet MSL, where specific regulations apply that require adherence to VFR guidelines for the safety and management of air traffic.