Can Helicopters Fly In The Rain?

Many travelers have had flights affected by inclement weather, whether in an airplane or something a little more unconventional like a hot air balloon (very sensitive indeed to overly windy conditions). Helicopters could also be considered rather less conventional aircraft, operating very differently to planes, and could be expected to be very sensitive to inclement weather as well. Brent Surace, a Hillsboro Heli Academy flight instructor, notes that mild to moderate rain showers don’t tend to affect a helicopter’s capacity to fly, or the pilot’s ability to fly it safely. However, Surace emphasizes, “rain is one thing, but more often than not storms are another animal altogether.”

It’s important to consider that rain can have an adverse effect on the pilot’s visibility, which can be one of the biggest factors in flight safety. Additional precautions are to be taken where rain is concerned, just as a motorist must take care to make use of their windshield wipers, be mindful of the routes they’re taking, the speed they’re traveling at and so on when driving in the rain. It’s also advised to avoid using faster cruise control in the rain. Just as in a car, moderate rain typically doesn’t prevent helicopter travel, but it can present a potential risk to be wary of.

One thing that deeply perturbs nervous flyers on the average airplane is turbulence, which can be caused by the flow of air and is rather sensitive to weather conditions. In a storm, these delicate conditions can be thrown out of balance by what’s known as convective turbulence, and helicopters themselves are generally considered trickier to pilot than planes. The Great North Air Ambulance Service notes that it generally can’t fly through the unpredictable winds and heavy rain of thunderstorms but adds that it can generally avoid them.

For helicopters with a main rotor and a tail rotor, the key concept for achieving and maintaining safe, even flight is in the balance between the two. The main rotor provides the lift that allows the bird to fly in the first place, while the tail rotor (the relatively teeny one you’ll see on the back of the chopper) is there to act against the torque generated by the primary rotor. Though helicopter blades are made of hardy materials, a change in the state of one of the rotors, such as damage or the accumulation of ice from freezing raindrops, can upset this balance. Therein lies a lot of the threat of severe rain.

Drivers must be very wary of ice on road surfaces in cold conditions, and it can be just as dangerous for helicopters. As the European Union Aviation Safety Agency puts it, accumulation of ice or snow can reduce the lift generated by the rotors, while simultaneously “add[ing] to the total weight of the aircraft, reducing performance and increasing the power required for taking off. Ice and snow can also affect the center of gravity, with the risk of shifting beyond acceptable limits.”

Though keeping track of weather forecasts is a crucial part of the pilot’s role, we all know that it can be impossible to be sure exactly when rain might begin, when a storm might take a turn for the worse, and so on. For this reason, they need to be equipped to act on the fly. The Federal Aviation Administration‘s Helicopter Flying Handbook notes that inclement weather has a particular effect on landings and provides guidance as to how to handle them in such cases: When the helicopter is operated with heavy loads in high density altitude or gusty wind conditions, best performance is achieved from a slightly increased airspeed in the descent.” An experienced pilot, then, knows that it’s possible to compensate for weather conditions that are less than ideal.

Instruments, such as advanced radar and GPS systems, help to ensure that the pilot isn’t reliant on direct visual input, so that navigation of the aircraft isn’t compromised by heavy rain. It’s not necessarily advanced equipment that makes the difference, though. Leigh Coates, veteran helicopter pilot, notes that one of the most important tools to arm yourself with for flying in the rain is a very low-tech one. “I always have a yellow rag at the ready,” Coates explained on her YouTube channel Leigh Coates, noting that condensation can quickly accumulate on the inside of a helicopter, a hazard in itself. The pilots who know their machines best know to reduce their altitude and speed in wet conditions, as well as using all manner of tools to fly safely in wet conditions. After all, pilots are well trained to avoid the harshest of nature’s challenges.