When you look at the weather forecast and see that rain is forecasted on the day of your flight, you might start to worry that your flight will be delayed.
Fortunately, rain by itself very rarely delays flights, though if other weather conditions like thunderstorms are present, it’s possible that a flight can be delayed.
In Some Instances, Rain May Delay Flights
As just mentioned, rain by itself very rarely delays flights, as planes can and will take off in the rain.
However, if the rainfall has ice or supercooled water droplets, taking off becomes more difficult. The presence of aircraft deicing facilities would then determine whether it’d be safe to take off.
Additionally, if the outside temperature is below freezing, the rain can freeze when it touches the ground.
When this happens, it creates slick runway conditions that make take-offs difficult.
There is No Official Amount of Rain That Will Delay Flights
There is no predetermined amount of rain that will suddenly stop planes from being able to take off.
This is because modern aircraft generate lift regardless of the heaviness of the rain.
The problem with heavy rainfall is a decrease in visibility and secondary weather conditions.
If the rainfall is heavy enough to impede a pilot’s vision, it is more likely that take off will be delayed, though this can vary by airline, with some airlines deciding to take on the slightly increased risk for scheduling purposes.
Flying in the Rain Can Be Dangerous
Light rain poses virtually no increased risk for planes taking off, as the rain is light enough to not impede a pilot’s vision.
However, flying in very heavy rain can impede a pilot’s vision, which may cause delays.
Landing in the Rain is Usually No Problem
Even if there is heavy rainfall when a plane wants to land, it will still rarely result in delays.
While heavy rain impacts visibility, making it difficult to land, commercial airliners are equipped with advanced instrument landing systems to make landing easier in low visibility conditions.
However, heavy clouding that can accompany heavy rainfall can be a barrier to landing for even large planes if the clouds extend low to the ground.
Rain Rarely Causes Planes to Crash
While weather conditions account for a quarter of air accidents, rain alone accounts for very, very few crashes.
There have been accidents due to rain, though, including Air India Express Flight 1344 that crashed when attempting to land under heavy rain, and Garuda Indonesia flight 421 that experienced a flameout because of frozen rainfall.
Rain Won’t Cause Turbulence
Turbulence can be caused by many different factors, including wind, jet streams, storms, and other objects near a plane, including even another aircraft, which is known as wake turbulence.
In total, there are 8 different types of turbulence, which each have their own causes, including
- Clear Air Turbulence
- Thermal Turbulence
- Mechanical Turbulence
- Temperature Inversion Turbulence
- Frontal Turbulence
- Mountain Wave Turbulence
- Thunderstorm Turbulence
- Wake Turbulence
Rain by itself is not a cause of turbulence.
Thunderstorms Can Delay Flights
Thunderstorms can delay flights due to reduced visibility along with lightning, hail, icing, wind shear, and microbursts that may accompany the thunderstorm.
Once the thunderstorm has passed, planes are able to take off.
Planes already in the sky and wanting to land may also be delayed due to being forced to enter a holding pattern away from the storm, which will lead to a domino effect that will delay other flights.
Snow Can Also Delay Flights
Both light and heavy snowfall can cause flight delays.
Light snowfall will only cause flight delays if the airport lacks snow removal equipment.
Heavy snowfall, on the other hand, is much more likely to cause flight delays or even cancelations due to the reduced visibility, and may cause logistical problems that prevent ground staff from reaching airports.
Even Extreme Heat Will Delay Flights Too
Extreme heat can delay flights due to the lower air density at higher temperatures.
As warm air is less dense, a plane can’t generate as much lift in extreme heat, though this can be compensated by a longer runway that will give a plane more time to generate the necessary amount of lift to take off.