Geospatial Images and Clear Air Turbulence

Despite all of the positive advances in aviation weather prediction and modeling, you undoubtedly continue to experience problems and challenges with unexpected turbulence. 

There are different types of turbulence, but clear air turbulence or CAT is especially hazardous for pilots, crew, and passengers. One telling statistic is that turbulence incidents account for more than 70 percent of all weather-related incidents that can cause damage and injury. 

DTN Flight Route Alerting is a comprehensive 4D alerting engine. It monitors and accurately predicts the weather for flight planning, pre-flight briefing, flight following, and in-flight updates. Not only that, this patented solution simultaneously evaluates multiple flight plans in real-time.

It continually monitors the weather for any changes in conditions to give you the best possible route. In addition, this system is fully customizable to your specific thresholds and alert criteria. As a result, you can get your passengers safely to their destination.

While meteorologists can accurately forecast certain types of turbulence, other more subtle causes of turbulence are much more challenging to forecast. As a result, there can be errors ranging from over forecasting the event to missing it entirely.

Injury to flight attendants is the most common result of turbulence. This costs commercial airlines an estimated $9 to $11 million U.S. dollars (USD) per year in various associated expenses. In addition, turbulence-related delays and cancellations cost the industry an additional estimated $1 billion annually.

 

What is clear air turbulence?

There are three general types of turbulence:  boundary layer, mountain wave, and clear air turbulence. 

Boundary layer turbulence is caused by the interaction of a fluid with a solid boundary, such as a wing’s surface. This type of turbulence is common near airports and can cause airplane wings to vibrate, which makes it difficult for pilots to control the aircraft.

Mountain wave turbulence is caused by the wind blowing over mountains or hills. The turbulent air can cause airplanes to lose altitude unexpectedly.

To describe it in technical terms, clear air turbulence (CAT) refers to erratic air currents that occur in cloudless air between altitudes of 20,000 and 49,000 feet. Put simply in layman’s terms, clear air turbulence can be described as high-altitude bumpiness where there are no significant clouds or thunderstorm activity.

One of the main causes of clear air turbulence is strong vertical wind shear. According to sciencedirect.com, “KELVIN–HELMHOLTZ INSTABILITY (KHI) arises from micro-and mesoscale wind shear intensification, when smooth, wavelike oscillations within a sheared, statically stable layer grow in amplitude to the point where the wave crests overturn, or ‘break.’ Wave-breaking at wavelengths of hundreds of meters is highly effective in producing CAT, with a rapid cascade of energy from the KHI to smaller-scale turbulence and dissipation.”

Other sources of clear air turbulence are as follows:

• airflow over mountainous terrain 
• the effects of remote convection 

 

Why is clear air turbulence dangerous?

Clear air turbulence is the most dangerous kind of turbulence because, as the name implies, it takes place in clear air. There is often little or no warning in a typical precise air turbulence incident scenario when it hits. 

Unfortunately, it is possible to encounter clear air turbulence at any time during the flight. 

When a pilot is taken by surprise, and an aircraft is suddenly and violently tossed about by clear air turbulence, it can send items such as any unsecured carry-ons, carts, and even passengers or crew members tumbling. This unexpected chaos is more likely to be dangerous and cause potential injury when flying above 10,000 feet where passengers are unbuckled. 

Unfortunately, this situation has happened all too frequently. Dozens of passengers and flight attendants are injured in this way every year on U.S.-operated airlines; there may be an even higher rate of injury than official statistics show because many incidents likely go unreported.

 

How high-resolution geospatial weather information can help

As we have mentioned, clear air turbulence is notoriously difficult to observe. It can be even more challenging when clear air turbulence exists only on a small scale; satellite observations can help monitor larger-scale features or conditions that may lead to clear air turbulence.

For example, high-resolution geospatial satellite imagery can reveal the existence of weather features such as specific wave or water vapor patterns that may indicate a potential turbulence hazard. When combined with other observational systems, high-resolution geospatial weather information can help identify and give early warning to the presence of clear air turbulence.

The onboard instrument is capable of detecting clear air turbulence from approximately 10 miles away, thus giving the pilot about a 70-second warning at cruising speed. JAXA claims this can “halve aircraft accidents caused by clear air turbulence.”

The goal is for this technology to be further enhanced to make the onboard device smaller; it currently weighs over 180 pounds. The clear air turbulence can be detected from a greater distance, giving the pilots and crew enough time to react.

 

Flight alert routing

Turbulence forecasts help pilots fly smarter and safer.

The enhanced flight hazards model from DTN offers full, state-of-the-art Eddy Dissipation Rate (EDR) turbulence forecasts and an integrated view of the three types of turbulence: boundary layer, mountain wave, and clear air. Specific EDR values can be applied to your aircraft’s airframe-specific thresholds. They are specific to 22 flight levels, from FL010 to FL530.

DTN offers Flight Route Alerting as an additional service to help you quickly and easily determine if the weather will impact your flights. It supports safer operations, better planning, and in-flight alerts. This allows your pilots to make changes on route.

When it comes to your flights, you need to determine whether weather and turbulence will be an issue. You can get your passengers home safely using expert expertise from DTN’s 35 years of experience as an industry leader.

More importantly, Flight Route Alerting does more than make you aware of the dangers you face. During your flight, it continuously monitors its status and the status of up to 25 additional locations. 

Knowledge is power, and Flight Route Alerting gives you the knowledge and power over your flight until the flight is completed or canceled.

This combination of observations and forecasts allows you to have the best possible strategy for facing the challenge of clear air turbulence.