Heavy fighter jets are primarily designed for aerial combat, so it’s no surprise they can reach impressive heights.
But exactly how high can they fly? This seemingly simple question has stirred up lots of debate. Our article will give you a clear answer while also discussing what might happen if a military jet exceeds its maximum altitude.
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How High Can A Military Jet Fly?
Commercial jetliners can cruise 30,000 to 45,000 ft above sea level.
However, most are allowed to operate at up to 42,000 feet (fighter jets’ max altitude). This number is called the service ceiling, the highest point an aircraft model can reach without losing its steady climb rate of 100 ft per minute.
Record-Breaking Supersonic Fighter Jets
1. X-15
The North American X-15 broke new ground in hypersonic flight and space exploration after its first flight in 1959.
It marked a joint effort between North American Aviation (which designed the airframe) and Reaction Motor (responsible for the jet engines). This collaboration was part of the X-plane program, a series of experimental aircraft backed by both the US Air Force (USAF) and NASA.
In 1963, controlled by pilot Joseph Walker, the X-15 achieved the highest human-crewed military flight – 354,200 ft or 67 miles above the Earth’s surface.
However, some argue that the X-15 shouldn’t be considered an airplane. Rather, it’s more like a rocket due to its self-contained oxygen supply. Indeed, its missions reached such great heights that its pilots technically qualified as astronauts, which led to the development of the very first ‘space suits’ for their protection.
2. MiG-25 E-266M
The Mikoyan-Gurevich MiG-25 (NATO designation: “Foxbat”) was a high-performance interceptor and reconnaissance aircraft designed by the Soviet Union’s Mikoyan Design Bureau. The E-266M was a special version of this plane, primarily intended to break speed and altitude records.
Smithsonian Magazine reported that Alexandr Fedotov set the Absolute Altitude Record on August 31, 1977, flying the E-266M to an astonishing height of 123,523 feet.
To this day, the number remains the highest altitude ever reached by any ground-launched plane. Unfortunately, the record-breaker Fedotov eventually lost his life in 1984 during a test flight of the MiG-31.
3. MiG-29
Miokayn Design Bureau designed this twin-engine, supersonic jet fighter aircraft in the Soviet Union.
It was originally intended as an air superiority fighter for the Soviet Air Force but now has evolved into a multirole combat aircraft. Throughout the past decades, MiG-29 has found success in various roles, including aerial interception, air defense, and ground attack.
MiG-29 offers a unique experience for those willing to pay: High-Altitude Flights, also known as Edge-of-Space Flights. These Soviet aircraft can soar to a guaranteed height of 55,440 feet (10.5 miles), potentially climbing even higher to about 11.8 miles.
The plane’s official service ceiling is about 59,100 feet (11.2 miles), yet MiGFlug claims they’ve pushed the boundaries to 75,459 feet (14.3 miles). They currently operate at lower altitudes due to a drop in their speed limitation from Mach 1.7 to Mach 1.9.
4. SR-71 Blackbird
Altitudes aside, the SR-71 is considered one of the most legendary American long-range, strategic reconnaissance aircraft that dominated the skies during the Cold War. Its airframe was made from titanium (a revolutionary material for the time), able to withstand the immense heat generated by air friction at such high speeds.
Resources have reported that the Lockheed SR-71 “Blackbird” set the global altitude record among air-breathing planes (excluding rocket models like the X-15) at 85,135 feet.
NASA confirms the SR-71 stays unmatched as the highest-flying model aircraft ever made. Many believe the SR-71 can achieve even greater altitudes, but to this day, other more specific details are still classified.
What Happens If A Jet Flies Too High?
Few (if not none) fighter jets can exceed their maximum altitude for three reasons.
Cabin Pressure Difference
Proper cabin pressure is very important for everyone’s comfort once the plane reaches high altitudes. Or else, they would struggle to breathe if there’s no pressurized cabin!
As the plane ascends, the pressure difference between the outside and inside only increases, peaking at about 9 PSI (pounds per square inch) around 43,000 feet. Going beyond this threshold not only endangers people but also brings catastrophic damage to the aircraft’s structure.
Lacking A Powerful Engine Thrust
As they climb to high altitudes where the surrounding air becomes thinner, too little air passes through the engines to generate the necessary thrust that keeps the aircraft flying.
The issue only worsens with higher temperatures, which means the plane’s maximum altitude is even lower on hot days. As a result, the plane can no longer maintain a rate of climb of at least 300 ft. per minute.
Control Issues
At this rate, the pilot must increase the angle of attack to generate more lift at higher altitudes due to thinner air (as mentioned earlier).
Unfortunately, there’s a very critical limit to this climb angle. If the angle of attack becomes too high, the airflow over the wings will become turbulent and separate, and the plane’s wings will not be able to generate any lift at all!
Combined with the lack of thrust and engine power, maintaining a stable flight as the altitude increases beyond the threshold is downright impossible; the aircraft either goes sluggishly or requires insane control adjustments to stay on course.
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Conclusion
Plenty of modern fighter jets have soared well above the typical 42,000-foot mark. The X-5, reaching an astonishing 354,200 feet, is an outstanding case, though there are many heated debates on whether it qualifies as a fighter jet.
Aside from these special models, most modern fighters and business jets stick well below their altitude ceiling. If you have any other questions, don’t hesitate to contact us.
