# Helicopters and operational height limits

• fresh_42
In summary: Additionally, the weight of the helicopter and outside air temperature also play a role in determining the maximum altitude it can reach. This is due to the decreased performance of the engines and rotors at higher altitudes and temperatures. Ultimately, the maximum altitude a helicopter can fly is determined by a combination of these factors and can vary depending on the specific aircraft and flight conditions.
fresh_42
Staff Emeritus
2023 Award
I know that helicopters cannot fly arbitrary high and 5,000 m are considered as the average limit. In a quick search I also found out, that a AS 350 B3+ has been landed on the Everest (8,848 m, 2005) and another AS 350 has (unofficially) reached 12,954 m in 2012 (official record: 12,442 m by a SA-315 in 1972).

Now the question: What runs out first: oxygen for the engines or air for the rotors?

It's largely irrelevant deciding which parameter would "run out first," I'd say they both limit the operational altitude for a helicopter. Rotors would have to spin at higher speeds in the thin air (or operate at a higher angle of attack potentially reducing efficiency), and oxygen availability for the engine will become a problem as well.

Here is some useful reading on the topic: https://www.quora.com/Whats-the-highest-altitude-an-average-helicopter-can-fly

Some points brought up in the above page:
• There isn't going to be a set altitude that a helicopter can get to. There are numerous charts in helicopter performance planning manuals that allow pilots to figure out a maximum altitude. This altitude will be a function of aircraft gross weight, Mean Sea Level elevation and temperature. Engines and Rotor systems are less efficient at higher temperatures/altitude and they have work harder when the aircraft weighs more. Temperature and Altitude factored together gives you density altitude. Most aircraft's service ceilings are based on density altitude.
• For level flight most helicopters can fly up over 10000 feet MSL. Without a pressurized cabin the FAA requires oxygen for flights above 12000 MSL longer than 30 minutes and all flights above 14000 MSL.

fresh_42

It is difficult to determine which runs out first, as both oxygen for the engines and air for the rotors are essential for the helicopter to continue flying at high altitudes. However, it is likely that oxygen for the engines would run out first, as the thinner air at high altitudes would require the engines to work harder and therefore consume more oxygen. The helicopter would also need to maintain a certain speed to keep the rotors spinning, so if the engines were to fail due to lack of oxygen, the rotors would also stop functioning.

## 1. What is the maximum operational height limit for a helicopter?

The maximum operational height limit for a helicopter varies depending on several factors such as the type and model of the helicopter, weather conditions, and pilot experience. In general, helicopters can fly up to 10,000 feet above sea level, but some models have a maximum operational height limit of 18,000 feet.

## 2. Why are there operational height limits for helicopters?

Operational height limits for helicopters are in place for safety reasons. Flying at higher altitudes increases the risk of engine failure due to lower air density, which can make it difficult for the helicopter to maintain lift. Additionally, at higher altitudes, pilots may experience reduced visibility and more unpredictable wind patterns, making it more challenging to control the helicopter.

## 3. Can helicopters fly above the maximum operational height limit?

Technically, yes, helicopters can fly above the maximum operational height limit. However, it is not recommended as it may pose safety risks. Pilots are trained to adhere to operational height limits for the safety of themselves and their passengers.

## 4. What happens if a helicopter exceeds the maximum operational height limit?

If a helicopter exceeds the maximum operational height limit, it may experience a loss of engine power due to lower air density and increased turbulence. The pilot may also experience difficulty controlling the helicopter, which can lead to accidents. Additionally, exceeding the operational height limit can result in fines or penalties for the pilot and operator.

## 5. Can operational height limits for helicopters be changed?

Yes, operational height limits for helicopters can be changed. They are often reviewed and updated based on advancements in technology and safety standards. However, any changes to operational height limits must be approved by aviation authorities and implemented through proper training and procedures.