Microbursts: The Invisible Aviation Threat

The Crash of Flight 191

On August 2, 1985, Delta Flight 191 approached Dallas/Fort Worth International Airport. The pilots saw a thunderstorm ahead, but it looked manageable. Suddenly, the aircraft encountered a massive performance loss. It slammed into the ground short of the runway, killing 137 people.

The cause? A microburst, a localized column of sinking air (downdraft) within a thunderstorm.

Since then, aviation safety has improved dramatically, but microbursts remain a terrifying and elusive phenomenon. They are small (less than 4km wide), short-lived (5-15 minutes), and notoriously difficult to detect with standard radar until the air actually hits the ground. By then, for a plane on final approach, it is often too late.

The Physics of the Downward Smash

A microburst begins when dry air enters a thunderstorm. This dry air causes rain to evaporate rapidly (virga), which cools the air. Cold air is denser than warm air, so it begins to sink. As it sinks, it gains momentum, crashing toward the earth at speeds exceeding 6,000 feet per minute.

When this column of air hits the ground, it spreads out in all directions, creating a "starburst" pattern of wind.

For a pilot, this is a deadly trap:

1. Headwind: Entering the microburst, the plane faces a strong headwind, increasing lift. The pilot instinctively reduces power.
2. Downdraft: Suddenly, the plane is pushed down by the sinking air.
3. Tailwind: Exiting the core, the wind shifts to a tailwind, destroying lift. With reduced power and low altitude, recovery is impossible.

Deep Dive: The Detection Gap

Airports currently use LLWAS (Low-Level Windshear Alert System) and TDWR (Terminal Doppler Weather Radar). These systems are good, but they have limitations:

• Line of Sight: Doppler radar can only measure wind moving toward or away from the radar. It cannot see wind moving perpendicular to the beam.
• Lag Time: Radar scans take time. A microburst can form and dissipate in the time it takes for a radar dish to complete a full volumetric scan (4-6 minutes).
• Dry Microbursts: In regions like the High Plains or Western US, microbursts can occur with little to no rain. Radar, which bounces signals off raindrops, is practically blind to these "dry" events.

Skyfora's Advantage: Seeing the Precursors

Skyfora addresses the microburst threat not by watching the wind, but by watching the thermodynamics that create it.

Remember, microbursts are driven by rapid cooling and water vapor gradients. Skyfora’s GNSS tomography provides:

1. 3D and 4D Water Vapor Profiling: We can detect the intrusion of dry air into a moist storm cell, the exact recipe for evaporative cooling that triggers a microburst.
2. Continuous Realtime Monitoring: Unlike radar which scans mechanically, GNSS signals are continuous. We update atmospheric profiles every few minutes.
3. Network Density: By surrounding an airport with GNSS sensors, we create a dense mesh that captures the localized atmospheric instability before the downdraft begins.

We are effectively moving from "reactive" detection (the wind is blowing now) to "predictive" detection (the conditions for a microburst are forming).

Practical Applications

• Approach Planning: Air Traffic Control (ATC) can increase separation between aircraft or change runways 10 minutes earlier, avoiding the go-around procedures that disrupt schedules.
• Urban Air Mobility (UAM): As we move toward eVTOLs and air taxis, these smaller aircraft are far more susceptible to microbursts than heavy jets. Hyperlocal GNSS sensing will be a regulatory requirement for safe urban flight corridors.

Conclusion

Microbursts are one of nature's most violent local events, releasing the energy equivalent of a small bomb in a matter of minutes. While we cannot stop them, we can strip away their invisibility. By looking at the thermodynamic skeleton of a storm using GNSS, Skyfora can help ensure that pilots never have to fly blind into sinking air again.