How high can military aircraft fly?

The altitude a military aircraft can fly depends partly on the type of aircraft and whether it is "in flight" or not.

Aircraft SR-71 "Blackbird". Photo: Simple Flying

In some ways, the SR-71 "Blackbird" is the fastest manned aircraft in the world and also holds the record for highest flight. But both the X-15 and the MiG E-266M compete for the title. All three of these military records were set during the Cold War arms race of the 1960s and 1970s and have never been broken since then, according to Simple Flying . It seems that flying higher is not the main focus of military aviation.

According to PhysLink.com, most US military aircraft can exceed an altitude of 15,240 m if they really try, but their exact limits are mostly classified information. Many wide-body commercial jets have an altitude limit of 13,106 m (although they can fly higher). When planes fly high in the atmosphere, they need to be pressurized (like commercial jets) or the pilot needs to wear a pressurized suit.

As it rises higher in Earth's atmosphere, oxygen becomes thinner until there is not enough oxygen left in the air to continuously burn jet fuel. Commercial jet aircraft usually fly at an altitude of 9,144 - 13,716 m (mainly a maximum altitude of 12,802 m). According to the US Air Force, the famous U2 reconnaissance aircraft often flies higher than 21,366 m, while PhyLink.com says the U2 can cruise at altitudes of up to 27,432 m. Stealth bombers cruise at 15,240 m. The Russian MiG-31 model has the highest altitude limit of any fighter aircraft in operation today (at 25,000 m).

The three military aircraft that are said to fly at the highest altitude include the US X-15, the Soviet Union's MiG-25 E-266M and the US SR-71 Blackbird. All three of these aircraft broke world records in their own categories. While the records of the MiG-25 E-266M and SR-71 remain the same today, the civilian SpaceShipOne surpassed the world record of the X-15 in 2004.

X-15

X-15 is an experimental rocket ship built by the US Air Force in cooperation with NASA to explore the edge of space. This is the world's first manned supersonic aircraft and the first aircraft to reach speeds of Mach 4, 5, and 6 (4,939, 6,174 and 7,409 km/h). The vehicle also holds the world record for fastest manned flight (Mach 6.7 or 8,273 km/h), set in 1967. The X-15 also set the record for highest manned military flight, reaching 107.8 km in 1963 with pilot Joseph Walker. But some people argue that the X-15 is not really an airplane. Instead, it is a rocket with its own oxygen supply.

MiG-25 (E-266M)

According to Smithsonian Magazine, the record for absolute altitude belongs to Soviet pilot Alexandr Fedotov, set on August 31, 1977 when he flew the MiG E-266M to an altitude of 37,650 m). This is the absolute altitude record for aircraft taking off from the ground and has never been broken. Fedotov died on April 4, 1984 while testing the MiG-31 aircraft.

SR-71 "Blackbird"

According to PhysLink.com, the world record for speed and altitude for aircraft using jet engines is 25,949 m achieved by the Lockheed SR-71 "Blackbird" aircraft in 1976. The SR-71 was designed designed to cruise at Mach 3.2 (3,951 km/h) and break the speed record for horizontal flight at constant altitude (3,529 km/h). The SR-71 can fly at higher speeds and higher altitudes, but these limitations are confidential information. NASA says the SR-71 is the world's fastest and tallest aircraft ever built.