How high can you fly an airplane?

The maximum altitude an airplane can fly depends on its type and design. Commercial airliners typically cruise at altitudes between 30,000 and 40,000 feet, while military jets and specialized aircraft can reach altitudes above 60,000 feet. The highest recorded flight altitude was achieved by the NASA/USAF X-15, which reached about 354,000 feet. However, practical limits for most aircraft are significantly lower due to factors like oxygen availability and engine performance.