Airplanes have windshield wipers – and they are actually the most common rain protection feature found on planes (the others being chemical rain repellents, hydrophobic seal coating, and pneumatic rain removal systems).
However, do all types of aircraft have windshield wipers, or are they only found on commercial airliners?
How do a plane’s windshield wipers even work?
What happens if the windshield wipers fail?
In this article, we answer these questions as well as others, so you can find out everything there is to know about airplanes and windshield wipers.
Not All Planes Have Windshield Wipers
If we take private planes to mean the small, single-engine planes that many private pilot license owners fly, then it’s unlikely to see them equipped with windshield wipers.
This is because the plane’s propeller air stream will blow the rain right off the windshield. If the rain is so heavy that the rain won’t blow off, it means that a pilot shouldn’t be flying in the first place due to poor visibility.
Commercial planes that are used in the airline industry, such as the Boeing 737, Boeing 747, Airbus 330 and many other variants, have windshield wipers.
During a rainy takeoff, the pilot will switch on the windshield wipers (there are two speeds to choose from) to maintain visibility. This is because as the plane gains speed along the ground, water from the nose cone will run over the windshield and reduce visibility.
Military planes, such as fighter jets, do not have windshield wipers, though may have a system to clear the rain.
Fighter jets can reach extremely high speeds, which means that the rain easily blows off the canopy. However, when necessary, the pilot can bleed air from the engine’s compressor section onto the front canopy and clear the rain, ice and snow through high pressure and heat.
How Windshield Wipers On Planes Work
Most planes that are equipped with windshield wipers use electrical motors to function, though hydraulic wiper motors are another alternative. Windshield systems consist of a wiper, wiper arm, and a wiper motor/converter.
Generally, windshield wipers on a plane will be found on the pilot’s side as well as the co-pilot’s side. This is because in the event that one of the systems fails, clear vision can still be maintained.
Windshield wiper systems are engineered to not exceed a certain speed because damage to the wiper assembly can be caused at higher speeds, rendering the wipers inoperable.
When Pilots Will Use the Windshield Wipers
A pilot will only use windshield wipers (or other rain removal systems) when taxiing, which is when a plane will slowly move along the ground before takeoff or after landing. This ensures that the approach and departure paths, as well as the runway environment, can clearly be seen. Once a plane is in-flight, the wipers are typically inoperative
What Happens If There is a Problem With the Windshield Wipers
If the wiper system fails on one side, the pilot with the functional wiper system will only be allowed to fly the aircraft.
In the event that both systems fail, which in any case is very unlikely, the pilot is required to only takeoff and land in visual meteorological conditions, which are conditions in which pilots have sufficient visibility to fly an aircraft while maintaining visual separation from terrain and other aircraft.
How Rain is Cleared on Planes
Besides windshield wipers, chemical rain repellents, hydrophobic seal coating, and pneumatic rain removal systems can all be used to clear the rain and improve visibility.
- Chemical Rain Repellents
Chemical rain repellents work by drawing water up into beads that will then take up only a small portion of the glass, thereby increasing visibility. Application is handled via a switch or push button in the cockpit.
- Hydrophobic Seal Coating
Most new aircraft windshields are treated with hydrophobic seal coating. It works similarly to chemical rain repellents in the sense that raindrops are beaded up, take up only a small portion of the windshield and then roll off.
Hydrophobic seal coating is an alternative to chemical repellents while having the benefit of lasting longer. However, the downside is that the windshield will periodically require coating restoration, which will take more time and effort than simply refilling the chemical repellent tanks.
- Pneumatic Rain Removal Systems
Pneumatic rain removal systems work by using a flow of heated air over the windshield to break the rain drops up, so they can more easily be blown away, as well as preventing the rain drops from freezing. Pneumatic rain removal systems are particularly effective in heavy rain.