What is the airspace above 18000 feet?

Jets are the primary user of Class A airspace. It ranges from 18,000 feet (Flight Level 180) to 60,000 feet (FL600). Altitudes 18,000 feet and above are called Flight Levels (FL). Class A airspace is not specifically charted on aeronautical charts.



In the United States and many other ICAO-compliant regions in 2026, the airspace from 18,000 feet MSL (Mean Sea Level) up to Flight Level 600 (approximately 60,000 feet) is classified as Class A Airspace. This is the most restrictive and highly controlled airspace in the world. It is the exclusive domain of high-altitude commercial airliners, military jets, and high-performance business aircraft. Within Class A, all flights must be conducted under Instrument Flight Rules (IFR), meaning the pilot must be instrument-rated and the aircraft must be equipped for "zero-visibility" flying. Every aircraft in this airspace is under the direct control of an Air Route Traffic Control Center (ARTCC) and must be equipped with a transponder that provides altitude and location data to the "Center" controllers. Pilots do not use altimeter settings based on local weather; instead, they all set their altimeters to a standard 29.92 inches of mercury, and altitudes are referred to as "Flight Levels" (e.g., 18,000 feet is FL180). This ensures that all high-speed traffic has a standardized vertical separation, preventing mid-air collisions in the busy "highways" of the sky.

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In the 1900s, Hungarian physicist Theodore von Kármán determined the boundary to be around 50 miles up, or roughly 80 kilometers above sea level. Today, though, the Kármán line is set at what NOAA calls “an imaginary boundary” that's 62 miles up, or roughly a hundred kilometers above sea level.

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Vertical boundary The Fédération Aéronautique Internationale has established the Kármán line—at an altitude of 100 km (62 mi)—as the boundary between the Earth's atmosphere and outer space, while the United States considers anyone who has flown above 80 kilometres (50 mi) to be an astronaut.

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Nevertheless, certain exceptional aircraft like the Concorde and the Tupolev Tu-144 have managed to ascend to altitudes of FL600 (equivalent to 60,000 feet).

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As the federal authority over operations in all airspace and the regulating authority over operations, the FAA will ensure that the ETM cooperative vision aligns with agency goals and meets the requirements for safe and efficient operations.

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Modern airliners have flight management computers that will begin a descent from 30,000 feet, approximately 100 miles from the destination planning an idle descent. The computer calculates a vertical path based on the approach and landing information programmed by the pilots.

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The VFR Cruising Altitude rule does not apply below 3,000 feet AGL. There are some altitudes, however, that pilots seem to choose for level flight. Close to sea level they are 1000, 1500, 2000 and 2500. They are easy to read and remember on an altimeter.

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B4UFLY Mobile App Download the FAA's safety app, which provides real-time information about airspace restrictions and other flying requirements based on your GPS location.

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Class G airspace will always start at the ground and go up to 14,500' msl as a maximum.

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Can you fly at 80000 feet? The US Air Force U-2 reconnaissance aircraft flies at 72 000 feet almost every day for many hours. The world's fastest manned aircraft, the SR-71, flew for many years at 80 000 feet and higher.

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white was the first pilot to fly any aircraft faster than mach 4, 5 and 6, as well as the first to fly above 200,000 and 300,000 feet. he set the only official world record of the X-15 program when he flew to 314,750 feet on July 17, 1962, a f?d?ration a?ronautique internationale altitude record that still stands.

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Class A airspace generally begins from 18,000 feet mean sea level up to and including 60,000 feet. Operations in Class A are generally conducted under Instrument Flight Rules and primarily used by higher performance aircraft, airline and cargo operators, etc.

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In class E airspace, IFR aircraft are controlled by ATC. This might be a center facility (Air Route Traffic Control Center) or approach/departure facility. As a VFR aircraft, you aren't required to be in contact with ATC, but IFR aircraft must operate on an ATC clearance. That means the airspace is controlled.

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Class D areas should normally extend upward from the surface up to and including 2,500 feet AGL. The altitude must be converted to MSL and rounded to the nearest 100 feet.

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