Helicopter Operations in the Pattern
March 1, 2020
In addition to regular helicopter traffic including medical transport, law enforcement, military, and pipeline patrol, there are seasonal periods where you’ll find an increase in helicopter operations, such as wildfire, pesticide application and construction. Some pilots are more comfortable operating around helicopters than others.
A towered airport will assist in aircraft spacing, wake turbulence avoidance and general traffic flow between fixed wing and rotary wing aircraft. As many Minnesota airports are non-towered, what can we expect from helicopters in the airport operating area? First observations usually show that helicopters, generally, fly slower and steeper approaches to landing. Second, it is found that helicopters rarely land on the runway. They may fly their approach to the runway but land at a helipad, the tarmac or a suitable clear area on the airport. Seeing a helicopter flying across the runway to a landing location at about one hundred feet off the ground is called an air taxi and is a normal operation. It minimizes the downwash effect, saves fuel and minimizes impact on fixed wing traffic in the runway environment. However, standard practice does state that no operator should air taxi over aircraft, vehicles or personnel.
Helicopters produce different types of air movement depending on the mode of flight. A hover or slow hover taxi produces very high winds below and around the main rotor. A helicopter in forward flight will produce trailing vortices similar to the vortices produced by fixed wing aircraft. Since helicopters are usually flying slower forward speeds, these vortices can be very strong and should be avoided similar to vortices from other large aircraft. This can be even more complicated due to helicopters flying in areas other than the standard airport pattern. A good rule of thumb is to remain three rotor diameters away from helicopters in any flight regime.
Advisory Circular 90-66B states that helicopters must avoid the flow of fixed wing aircraft when approaching and landing at a helipad or other suitable landing area (other than the active runway). When landing on the active runway, helicopters may fly a pattern similar to the fixed wing aircraft but 500 feet lower and even on the opposite side of the runway. Don’t forget about the need for helicopter pilots to practice autorotation landings (simulated engine failure) which involves a steep angle of approach and high descent rate. You will commonly see these actions around helicopter operations too (they are pretty interesting to watch).
Helicopters provide many services to citizens across the country, we are thankful they are part of our aviation family. Be aware of the differences they pose in the airport environment and help keep us all flying safely.