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A mountain in the way of the third runway

Hong Kong is set to build a third runway for Chek Lap Kok airport, but there are some stubborn physical constraints.

Sitting under airspace required for Chek Lap Kok’s proposed third runway, a firing range used by the Chinese army and the police is considered a threat to planes flying overhead. If the firing range isn’t removed by the time construction finishes, then the number of flights arriving on the new landing strip looks set to be cut. The South China Morning Post explains the latest issue to overshadow one of the world’s most congested international airports.


Recommended escape route for jets on third runway

Around 10km north of Chek Lap Kok near Tuen Mun lies Castle Peak. It is a vast area of greenbelt land in the northwest New Territories, one of the few undeveloped areas of land in Hong Kong not classified as a country park nor earmarked for development.

This land contains the site of a vast firing range used by China’s People’s Liberation Army and the Hong Kong police. The site is so active that aircraft overhead cannot fly below 914 metres. Security exercises take place every Monday to Friday throughout the year in this, one of the remotest and most deserted areas of the city. A flight path for jets aborting landings on the proposed third runway sits in the crosshairs of this no-fly zone. The firing activity poses a hazard to planes. A plane approaching the runway needs a certain amount of airspace in case it needs to abort the landing at the last minute. Planes will have to climb much steeper to avoid the no-fly zone, increasing the risk of the manoeuvre.

Frequent firing by troops at the Castle Peak site threatens to reduce such airspace and limit the number of planes that can land. The distance gives commercial jets clear altitude to avoid the ammunition firing and Castle Peak itself – which stands 583 metres high. Atop of that is a broadcast tower for television satellites which stretches up to 590 metres. These three things are a problem for the third runway, say the government’s airport consultants.

Almost all of the airspace above Castle Peak sits within restricted airspace. It’s officially known as “Danger Zone 5”. Pilots are expected to navigate a narrow flight path that can fly high enough to reach at least 914 metres before entering the danger zone to avoid the terrain and the flight restrictions. In a worst-case scenario, aircraft aborting a landing would enter the firing range at a height as low as 526 metres.

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Panoramic view taken in 2012 from Lantau Island of the Hong Kong International Airport with Castle Peak in the background. Photo: Nora Tam/SCMP

What does the government say about Danger Zone 5?

Britain’s National Air Traffic Services (NATS), the government’s airport consultants, recommended relocating the firing range, known as Danger Zone 5, in 2008. They said the third runway would risk being little used otherwise.

A Civil Aviation Department source said the government remained open to its consultant’s warning and that the firing range could be moved before the third runway was completed – but this would mean the PLA having to cede control of a key resource.

“The missed approach procedure has been operating smoothly since its implementation and an effective communication mechanism is also in place with the firing zone and the PLA,” the source said. “We are considering all possible options and will take necessary action during detailed procedure design.”

However, the department’s official response insisted it would comply with UN aviation safety rules when planning the third runway and that Hong Kong’s existing two runways managed to operate aborted landings above the danger zone “safely and efficiently at all times”.

But the consultants say there is not enough space for planes to safely climb over Castle Peak and the firing range with the third runway in place. If a jet attempted to fly above the firing range, it would need to climb at a minimum gradient of more than 10 per cent, which NATS branded as “operationally unacceptable”.

Seven per cent is considered the maximum limit.


Negative outlook

What did the former civil aviation chief, pilots, air traffic controller, and anti-third runway campaigner have to say?

“If NATS says it has to be addressed, it has to be, otherwise that procedure cannot be used, which will affect the airport capacity,” said former department chief Albert Lam Kwong-yu. “But first the PLA must agree to remove it.”

Michael Mo Kwan-tai, the spokesman for the Airport Development Concern Network, said the newly created missed approach flight path “is clearly very close to” to the danger zone. “The broadcast tower would become a threat if the firing zone isn’t relocated,” Mo said, because planes would have to avoid two major obstructions in close proximity. NATS says the tower would need to be removed.

A senior air traffic controller in Hong Kong said: “I can’t see how the firing range survives.”

Consultants carved out the escape route after assuming airspace would be merged with the Pearl River Delta and the firing range would be deactivated.

The Hong Kong Airline Pilots Association warned that older aircraft were not capable of such manoeuvres. The PLA did not respond to repeated requests for comment.

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