Which altitude are aircraft supposed to be flying?

Actual altitude levels of aircraft in flight vary based on several factors such as aircraft type and performance, weather and weight of the aircraft. It is difficult for people standing on the ground to gauge aircraft altitude visually. Large size aircraft may appear to be lower than smaller aircraft because their size makes them look closer to us. Smaller aircraft may seem higher when following a larger size aircraft at the same altitude. The MAC FlightTracker tool takes the guesswork out of gauging aircraft altitude because the animated flight track replay offers an option to display altitudes for each aircraft as it navigates through the airspace above us.

Aircraft climb rates are affected by engine performance, airframe aerodynamics, air temperature, air density, and wind speed:

  • Climb profiles vary considerably among aircraft types, but modern aircraft typically have improved wing and airframe designs compared to older model aircraft. 
  • Air temperature and air density affect climb rates because as the temperature increases, air density decreases which reduces aircraft performance and results in a longer takeoff distance and a lower climb rate. 
  • Wind speed is important because a strong headwind (coming toward the front of the aircraft) increases lift as a result of the faster airflow over an aircraft's wings. This increased lift results in increased climb rates and reduced takeoff and landing distance on the runway. 

Federal Aviation Regulations 14. C.F.R. Part 91.119 Minimum Safe Altitudes states that, except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes:

  1. (a) Anywhere. An altitude allowing, if a power unit fails, an emergency landing without undue hazard to persons or property on the surface.
  2. (b) Over congested areas. Over any congested area of a city, town, or settlement, or over any open air assembly of persons, an altitude of 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet of the aircraft.
  3. (c) Over other than congested areas. An altitude of 500 feet above the surface, except over open water or sparsely populated areas. In those cases, the aircraft may not be operated closer than 500 feet to any person, vessel, vehicle, or structure.
  4. (d) Helicopters. Helicopters may be operated at less than the minimums prescribed in paragraph (b) or (c) of this section if the operation is conducted without hazard to persons or property on the surface. In addition, each person operating a helicopter shall comply with any routes or altitudes specifically prescribed for helicopters by the Administrator.

For information about reporting low flying aircraft, please visit: Contact FAA for Low Flying Aircraft Safety Concerns

Updated 2/2/2020