What is a microburst in aviation?

A microburst is a highly localized, intense downdraft that spreads out rapidly upon reaching the ground, causing severe windshear and posing a major hazard to aircraft, especially during takeoff and landing.

How long does a typical microburst last?

Microbursts usually last from 1 to 5 minutes, with dangerous conditions sometimes persisting up to 15 minutes.

What is the difference between a microburst and a macroburst?

A microburst affects an area up to 4 km in diameter and is short-lived, while a macroburst covers a larger area and lasts longer.

How can pilots detect or be warned of microbursts?

Detection systems like the Low Level Windshear Alert System (LLWAS) and Doppler radar provide warnings by monitoring rapid wind changes near airports.

What should pilots do if a microburst is reported near the runway?

Pilots should delay takeoff or landing until the hazard has passed, as attempting to operate in a microburst can be extremely dangerous.

Microbursts in Aviation

Hard4 min readMeteorology

Moderately Examined

Why this matters

Understanding microbursts is critical for pilots because these phenomena can cause sudden, severe wind shear that may lead to loss of control or insufficient runway performance during takeoff and landing. Recognizing the signs and knowing how to respond can prevent accidents and save lives.

Microbursts in aviation are highly localized, intense downdrafts that rapidly descend from thunderstorms and spread out at ground level, creating severe wind shear hazards. Their small size—typically less than 4 km in diameter—and short duration make them particularly dangerous during takeoff and landing, as they can cause abrupt changes in wind direction and speed.

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What is the primary hazard associated with a microburst during final approach?

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In depth

Explanation

What is a Microburst?

A microburst is a concentrated column of rapidly descending air, usually originating from a cumulonimbus cloud. When this downdraft hits the ground, it spreads out horizontally, creating intense and sudden wind shear. If the affected area exceeds 4 km in diameter, the phenomenon is classified as a macroburst instead.

Microburst Development and Types

Microbursts form when precipitation falls through dry air below the cloud base. As rain evaporates, it cools the descending air, making it denser and accelerating it downward. This process can be especially intense in dry conditions, leading to 'dry' microbursts. 'Wet' microbursts occur when precipitation reaches the surface, but both types can produce hazardous wind shear.

Duration and Effects

A microburst typically lasts between 1 and 5 minutes, with dangerous wind conditions persisting for up to 15 minutes. Wind speed changes of 50 knots or more are common, and extreme cases can see shifts up to 150 knots. The most hazardous moment is immediately after the downdraft impacts the ground, as the wind direction can shift rapidly from headwind to tailwind, causing sudden loss of lift and airspeed.

Operational Hazards: Takeoff and Landing

Aircraft encountering a microburst on approach will first experience a strong headwind, increasing airspeed and causing the aircraft to rise above the glide path. This is quickly followed by a downdraft and then a tailwind, leading to a rapid loss of airspeed and altitude. Immediate go-around with maximum power is the recommended response, but recovery depends on altitude, power reserve, and speed margin.

Detection and Avoidance

Microburst detection at airports relies on systems like the Low Level Windshear Alert System (LLWAS) and Doppler radar. These systems monitor wind changes and provide warnings to air traffic control. The safest action is to delay takeoff or landing if microbursts are suspected or detected, especially near thunderstorms or virga (evaporating precipitation) which can signal their presence.

The essentials

Key Points

A microburst is a small, intense downburst with a horizontal extent less than 4 km.

Microbursts develop from rapidly descending air, often beneath thunderstorms.

They can produce wind shear with speed changes of 50 knots or more.

Typical duration is 1–5 minutes, but hazardous effects may last up to 15 minutes.

Dry microbursts form when precipitation evaporates before reaching the ground, intensifying the downdraft.

Detection systems include LLWAS and Doppler radar; visual cues include virga and thunderstorm proximity.

The correct response to a microburst encounter on approach is an immediate go-around with full power.

Watch out

Exam Traps & Typical Mistakes

Confusing microbursts (less than 4 km wide) with macrobursts (larger and longer-lasting).

Assuming microbursts only occur with visible heavy rain—dry microbursts can occur with little or no surface precipitation.

Believing that a microburst's downdraft is warmer than the surrounding air; it is actually colder and denser.

Thinking microbursts only happen in tropical regions—they can occur wherever the right conditions exist.

Failing to recognize the need to delay takeoff or landing if microbursts are suspected, rather than trying to outfly the hazard.

Test yourself

Example Exam Questions

Question 2Easy

How does a microburst differ from a macroburst?

Question 3Medium

Which weather phenomenon is most likely to produce a microburst?

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