Safety in the Skies: Avoiding Turbulence with Doppler Lidars
17th September, 2020
For a long time, airports had to depend on radar to detect turbulence that can affect planes during takeoff or landing — a method that was less than ideal due to radar’s inability to function well on clear days. Today, however, many airports are also equipped with Doppler Lidars that can detect turbulence under good weather conditions — and Mitsubishi Electric is leading the way in this field.
Safe Flying in Any Weather
Statistically, you are much more likely to get into an accident while driving than to experience an incident while traveling by plane. Yet, perhaps coloring our views of airplane safety is the turbulence that can rock the plane during landing or takeoff — an experience that can be unnerving.
The Doppler Lidar is an instrument designed to address such fears. To help pilots avoid turbulence while taking off and landing, an airport needs to be able to measure the wind speed and direction in its vicinity. Radar-based instruments can only measure wind by bouncing radio waves off of rain droplets and clouds — in other words, they mainly work on cloudy or rainy days. The Doppler Lidar, however, can function effectively on a clear day. Using single-frequency pulsed lasers, the Doppler Lidar detects the movement of aerosols in the air (tiny particles between a tenth and several micrometers in diameter), from which it can determine the wind speed and direction in real-time.
"Our mission is to provide greater safety and comfort to passengers and aviation professionals alike," says Makoto Shibusawa, a senior manager at Mitsubishi Electric who led development on the company’s own Doppler Lidar. The device incorporates laser optics technologies developed through Mitsubishi Electric’s fiber-optic communication business, as well as signal-processing technologies developed through its weather radar business. "Some of the airports where we have installed our Doppler Lidars have very clean air with low aerosol quantities that make it difficult for most Doppler Lidars to cover long distances. However, our Doppler Lidar has performed consistently and reliably even in such environments — a testament to the quality of Mitsubishi Electric products."
To date, the Mitsubishi Electric Doppler Lidar has been installed at Haneda, Narita, and Kansai airports in Japan, as well as Hong Kong International (China), Antalya (Turkey), Nice Côte d'Azur (France), and Beijing Daxing International (China), with one scheduled to be installed at Henri Coandă International (Romania). Together, they represent a diverse mix of airport sizes and climates.
Any Doppler Lidar installed by an airport is required by the International Civil Aviation Organization (ICAO) to be able to detect turbulence both above the airport and in the airport’s vicinity, and to be able to update observational data every minute. The fact that the Mitsubishi Electric Doppler Lidar is used by so many different airports underlines its ability to cover both short and long distances without sacrificing the quality of its output.
"A lidar system can effectively detect the wind reversal that occurs in Nice Bay," says Jean-Luc Lampin an official at Météo-France — the French national meteorological agency — who supervised the installation of the Mitsubishi Electric Doppler Lidar at Nice Côte d'Azur. "The wind shear front sometimes moves back and forth along the coast, at up to 60 kilometers per hour. Thanks to Mitsubishi Electric’s long-range lidar system — which can probe 11 to 12 kilometers in every direction — we are able to warn air traffic control about impending wind reversals three minutes before they occur."
The secret to this Doppler Lidar’s adaptability lies in Mitsubishi Electric’s very own waveguide amplifier.
"Our waveguide amplifier is capable of amplifying frequencies with a high level of stability, which has allowed us to dramatically improve the range of our Doppler Lidar," says Shibusawa. "Meanwhile, our Doppler Lidar features a compact design that makes the instrument more durable, which helps airports lower maintenance costs."
Air Safety and Beyond
Shibusawa says that due to the high level of performance, stability, and environmental resistance exhibited by the Mitsubishi Electric Doppler Lidar, demand has been strong from airports located in areas with severe geographical or climatic conditions. However, he adds that major national and regional hubs have also shown considerable interest. They see the Mitsubishi Electric Doppler Lidar as a tool for promoting safety in the skies to travelers around the world.
"Large airports in particular place great importance on brand image," Shibusawa says. "Some airports that installed our Doppler Lidar organized grand ceremonies that showcased the instrument to dignitaries and the press, as a way to earn positive coverage both nationally and globally. Improving its brand by promoting its safety features can help an airport expand its business by securing the patronage of more airlines and enjoying an increase in visitors."
Mitsubishi Electric engineers are currently working on a compact and lightweight Doppler Lidar with an even higher level of performance that can be fitted on an aircraft.
"I truly believe that our Doppler Lidar is an immense contribution to society, as it can greatly improve the safety of plane passengers around the world," says Shibusawa. "Today, it is helping us ensure our safety in the skies, but tomorrow, it may be able to offer an even wider range of benefits, such as assistance to drones and other air mobility devices and the collection of weather and traffic data."
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