What specific weather conditions, and at what severity, typically lead to airport closures, either complete or partial? I’m interested in factors beyond just heavy snow or ice, so can you break down the thresholds for things like:

• Snow & Ice: What snowfall rate, accumulation level, or type of ice (freezing rain, sleet) warrants different levels of closure (e.g., runways closed, taxiways closed, entire airport shut down)? How do de-icing capabilities factor into the decision?

• Fog & Low Visibility: What visibility range (in meters or feet) necessitates closure? How does the presence of advanced landing systems (e.g., ILS CAT III) affect these minimums?

• Wind: What sustained wind speeds or wind gusts, and from what direction relative to the runways, are considered unsafe for takeoffs and landings? How do crosswinds play a role?

• Thunderstorms: What proximity of lightning strikes to the airfield triggers ground operations shutdowns? What criteria are used to determine when thunderstorm activity has cleared sufficiently to resume operations?

• Volcanic Ash: What concentration of volcanic ash in the atmosphere is considered dangerous for jet engines, and what are the typical protocols for airport closures in affected areas?

• Extreme Temperatures: At what extreme high or low temperatures do aircraft or airport equipment become unreliable, leading to closures? How do these temperature thresholds vary for different aircraft types and regions?

• Other factors: Are there any less common weather phenomena, like dust storms, strong temperature inversions, or extreme turbulence, that can also lead to airport shutdowns?

I’d also appreciate it if you could mention whether these thresholds and procedures tend to vary regionally (e.g., between North America, Europe, Asia) due to differences in infrastructure, training, and operational practices.

Answer

Airports can be shut down due to a variety of adverse weather conditions that compromise safety and visibility for aircraft operations. These conditions can be broadly categorized as:

1. Low Visibility:

• Fog: Dense fog reduces visibility below operational minimums, making it impossible for pilots to see the runway and surrounding terrain. This is one of the most common causes of airport closures.

• Heavy Rain: Intense rainfall significantly reduces visibility and can lead to hydroplaning on runways, affecting braking performance.

• Snow: Heavy snowfall reduces visibility, covers runway markings, and creates hazardous taxiing conditions.

• Blowing Snow/Dust: Wind can whip up freshly fallen snow or dry dust, severely reducing visibility and obscuring runway lights and markings.

• Smoke: Smoke from wildfires or industrial accidents can create widespread visibility restrictions near airports.

2. Precipitation:

• Snow: Accumulation of snow on runways and taxiways poses a significant risk to aircraft. It reduces braking action, makes it difficult to control aircraft during takeoff and landing, and can obscure runway markings.

• Ice: Ice on runways, taxiways, and aircraft surfaces is extremely dangerous. It drastically reduces friction, making it difficult to brake and control aircraft. Freezing rain is a particularly hazardous condition as it can quickly coat surfaces with a layer of ice.

• Sleet: Sleet, a form of ice pellets, can accumulate on surfaces and reduce braking action.

• Hail: Large hailstones can damage aircraft surfaces, including windshields and wings, and create hazardous landing conditions.

3. High Winds:

• Strong Winds: High winds, especially crosswinds and tailwinds, can exceed aircraft operational limits, making it dangerous to land or take off. They can also make it difficult to control aircraft on the ground.

• Wind Shear: Sudden changes in wind speed and direction, known as wind shear, can cause significant problems during takeoff and landing. This can occur at any altitude and is especially dangerous near thunderstorms and frontal systems.

• Turbulence: Severe turbulence can make it difficult for pilots to control aircraft and can cause passenger discomfort and potential injuries.

4. Thunderstorms:

• Lightning: Lightning strikes pose a risk to aircraft and ground personnel. Airport operations are often suspended during thunderstorms.

• Heavy Rain: As mentioned above, heavy rain associated with thunderstorms reduces visibility and can lead to hydroplaning.

• Hail: Hail can damage aircraft.

• Microbursts: Microbursts are localized columns of sinking air within a thunderstorm that can produce intense wind shear at the surface.

5. Other Atmospheric Phenomena:

• Volcanic Ash: Volcanic ash can damage aircraft engines and reduce visibility. Airports in areas prone to volcanic activity may be closed due to ash clouds.

• Extreme Temperatures: Extremely high temperatures can reduce aircraft engine performance and increase takeoff distances. Extremely low temperatures can cause equipment malfunctions and make aircraft starting difficult. Although rare, these extremes could potentially lead to airport closure.

The decision to close an airport is typically made by airport management in consultation with air traffic control and airlines. The decision is based on factors such as the severity of the weather conditions, the type of aircraft operating at the airport, and the availability of resources to mitigate the effects of the weather. The safety of passengers and crew is always the top priority.