VFR cruising altitude rules in the US and Canada In the US, there are specific VFR cruising altitudes, based on the aircraft's course, to assist pilots in separating their aircraft while operating under visual flight above 3,000 ft above the surface (AGL) but below 18,000 ft Mean Sea Level (MSL).

Under FAA regulations, the maximum altitude for Visual Flight Rules (VFR) flight in the United States is 17,999 feet Mean Sea Level (MSL). Once an aircraft reaches 18,000 feet MSL, it enters Class A Airspace, where VFR flight is strictly prohibited and all pilots must operate under Instrument Flight Rules (IFR) regardless of weather conditions. When flying VFR at or above 3,000 feet Above Ground Level (AGL) but below 18,000 feet MSL, pilots must adhere to "hemispheric cruising altitudes" to ensure traffic separation: if flying a magnetic course of 0° to 179°, you must fly at an odd thousand-foot altitude plus 500 feet (e.g., 3,500, 5,500). If flying a course of 180° to 359°, you must fly at an even thousand-foot altitude plus 500 feet (e.g., 4,500, 6,500). Additionally, pilots must maintain specific "VFR Weather Minimums," such as staying at least 1,000 feet above and below clouds when flying at high altitudes (above 10,000 feet MSL). Flying near the 18,000-foot limit also requires supplemental oxygen for the pilot if the flight duration at that altitude exceeds 30 minutes.