The “chop chop chop” sound of a helicopter as it flies overhead can appear deafening to many homeowners and any other people in the area, even more so than airplanes.

This is easily explained considering that helicopters, especially those used by law enforcement and emergency medical service agencies, are able to legally fly lower than aircraft.

But precisely how long can a helicopter fly?

FAA Minimum Safe Altitudes

The Federal Aviation Regulations (FARs) are rules prescribed by the Federal Aviation Administration (FAA) that govern all aviation activities in the United States.

FAR 91.119 is the relevant regulation that sets out the minimum safe altitudes allowed for flight, and is where we can find how low a helicopter is legally able to fly.

It states:

Except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes:

  • 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.
  • Over other than congested areas – An altitude of 500 feet above the surface except over open water or sparsely populated areas. In that case, the aircraft may not be operated closer than 500 feet to any person, vessel, vehicle, or structure.

In other words, if you live in a congested area, an aircraft is not allowed to fly any lower than 1,000 feet over the highest obstacle. If you live in a sparsely populated area, an aircraft is not allowed to fly any lower than 500 feet to any person, vessel, vehicle, or structure including your house.

However, helicopters don’t necessarily have to follow these regulations. A helicopter can legally fly at a lower altitude “if the operation is conducted without hazard to persons or property on the surface”.

This makes sense considering helicopters have unique operating characteristics that make them able to take off, fly, and land in tight areas and in surroundings in which airplanes are unable to do so.

As the Federal Aviation Regulations put it, helicopters are particularly useful for their “ability to execute pinpoint emergency landings during power-out emergencies”, though is by no means the only situation whereby a helicopter can fly at a lower altitude.

How Low Can Police & Military Helicopters Fly?

FAR 91.119 states that the “helicopter’s increased use by law enforcement and emergency medical service agencies requires added flexibility.” In other words, police helicopters are legally allowed to fly at lower altitudes when deemed necessary.

As military aircraft operations are generally not subject to the same FAA regulations as aircraft operations, helicopters used by the military are also allowed to fly at lower altitudes when it is deemed necessary, too.