Most commercial flights fly at 38,000 feet, above the Class B maximum height and there is not a specific limit imposed. British Airways' Chief Pilot Captain Al Bridger told MailOnline Travel that aviation industry speed limits differ from aircraft to aircraft.
What Causes Seasons on Earth? Seasons happen because Earth's axis is tilted at an angle of about 23.4 degrees and different parts of Earth receive more solar energy than others. Earth's orbit around the Sun is elliptical. Seasons are caused by Earth's axial tilt and temperatures and nature's processes are affected. Because of Earth's axial tilt (obliquity), our planet orbits the Sun on a slant which means different areas of Earth point toward or away from the Sun at different times of the year. Around the June solstice, the North Pole is tilted toward the Sun and the Northern Hemisphere gets more of the Sun's direct rays.
Seasons occur because the earth is tilted with respect to the sun. We rotate on an axis 23.4 degrees from vertical. In summer (northern hemisphere) the north pole is tilted toward the sun. At the same time the south pole is tilted away from the sun so it is winter there.