Measuring Weather at the Highest Airport in the World

Daocheng Yading Airport
Aviation and Road Solutions
Weather & Environment

Located well over 4 km above sea level, Daocheng?Yading Airport in China constitutes the highest civil?airport in the world. With Vaisala’s high-quality?equipment, Daocheng Yading manages to measure?the weather conditions despite the challenges?posed by its altitude and low temperatures.

Daocheng Yading Airport serves?Daocheng County in the Garzê? Tibetan Autonomous Prefecture of?Sichuan Provence in China. It sits?4,411 meters above sea? level and has?a runway that totals 4,200 meters?in length. As such, it is the world’s?highest civil airport.?Due to the complex geographical?environment and harsh climate, the?aircraft performance in Daocheng?Yading is greatly limited. For this?reason, it is particularly important to?measure the airport’s outline weather?parameters, such as wind, pressure,?temperature and humidity, as well?as specialized aviational indicators?like Runway Visual Range (RVR) and?present weather conditions.

Demanding Heights

The high altitude of Daocheng Yading?is the biggest challenge affecting the?airport’s operations. In addition to?the extreme weather conditions and?the complex geographical environment,?that is common for all highland?airports, the altitude of 4,411 meters?renders it unprecedentedly difficult?for aircrafts to approach and land on?the airport.?

In order to the help Daocheng?Yading battle the challenges posed?by its high location, Vaisala has?offered a complete meteorological?monitoring solution, Vaisala AviMet??Automated Weather Observing?System (AWOS), based on the particular?needs of the airport.?The Vaisala?AviMet? AWOS provides meteorological?data to the air traffic controllers?and pilots as well as meteorological?forecasters and observers, for?example.

Extreme weather can cause challenges?on the windy, high plateau?that Daocheng Yading is located on.?To measure RVR, Daocheng Yading?uses Vaisala?FS11 Visibility Sensors?and FS11P Present Weather Sensor,?providing information on prevailing?weather phenomena at the airport to?secure safe take-off and landing.?

When operating in high altitudes,?also the winds can be stronger than?nearer to the ground, making it?crucial to measure their strength and?impact on airport operations. The?design of the sensors ensures protection?against all windblown particles,?such as sand: thus the particles will?not distract the measurement in?the windy conditions. Additionally,?Daocheng Yading uses Vaisala’s Ultrasonic?Wind Speed Sensor WMT702?for accurate wind measurements.

Clouds can be relatively close?to the ground when operating in?high altitudes, affecting take-off and?landing. Vaisala?Ceilometer CL31?measures the height of clouds and?cloud coverage, being able to detect?three cloud layers simultaneously –?also during precipitation. CL31 hosts?excellent detection of low cloud?layers starting at a height of virtually?zero.

In great heights, air density and?pressure decrease. The thinner the?air is, the lower the engine performance?of the aircraft is as well,?creating the need for Daocheng?Yading’s exceptionally long runway:?4,200 meters ensures a safe take-off.?The Digital Barometer PTB330, with?Vaisala BAROCAP? technology and?three independent transducers for?optimal redundancy and measurement?quality control, enables the?airport to measure atmospheric pressure?accurately. Moreover, Vaisala?AWOS software ensures QNH and?QFE readings that are calculated to?fit especially high altitudes, like that
of Daocheng Yading.

Challenging Cold

Due to the heights and resulting low?temperatures, Daocheng Yading has?a long frost period and the climate?is cold. The harsh environment sets?also its own requirements for the?meteorological observation system?at the airport. The equipment has?to be able to adapt to the climate,?provide stable, accurate measurements?and resist the cold, characterized?by enormous differences in?temperature between day and night.?

Vaisala’s products are known?for performing in demanding and?varying climates from the tropic to?the arctic. The Visibility Sensors used?at Daocheng Yading are equipped?with high-power heaters that prevent?the effects of cold climate as well?as the accumulation of snow on the?sensors. Vaisala’s wind sensor is likewise
equipped with heating power.?The customer has been very?happy with Vaisala’s solution to?battle the demanding and cold?climate, as stated by the Meteorological?Department of Daocheng?Yading:

“After the system was set?up, Vaisala’s observation system has?provided us with stable data, and?it has adapted well to the climate.”

The ability of Vaisala’s equipment?to provide accurate data, perform?reliably and withstand demanding?conditions have made it the ideal?solution in the great heights of Daocheng?Yading.

About Daocheng Yading Airport

Daocheng Yading Airport is a civil airport in Garzê Tibetan Autonomous Prefecture. It is?located at Haizi Mountain, 50 km away from the north of Daocheng County. Situated 4,411?meters above sea level, it is the highest civil airport in the world.?Since opening in 2013, the airport has greatly improved the tourist traffic conditions in the?southwest of Garzê Prefecture, serving nearly 400,000 people from six counties in the?southern part of the prefecture as well as the neighboring cities and counties in Tibet and?Yunnan. It has opened a window to the outside world and promoted regional economic?development.

This article has 1st been published in a Vaisala News issue 201 in October 2017. You can also download the Vaisala News article as a pdf document.

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