FIVE aircraft were forced to circle in a holding pattern before landing and four others were prevented from taking off after a balloon was found floating above the Shenzhen International Airport on Monday.

The balloon was later shot down and the company who released it was fined.

Fifteen such incidents had been recorded since the start of this year, yesterday's Chinese-language newspapers reported. Balloons near airports could lead to a serious air crash with heavy casulties, the reports said.

Airport staff members discovered a black dot above a village near the airport at about 12:20 p.m. Monday. It turned out to be a hydrogen balloon with a scroll tied to it. To prevent it from interfering with aircraft, the airport authority shot and deflated the balloon at about 12:30 p.m.

Investigations showed that the balloon belonged to Shenzhen Lisheng Electronics Co. Ltd. and was released at a ceremony held by the company. The city's meteorological authority decided to impose a fine of 20,000 yuan (US$2,632) on Lisheng Electronics.

The balloon was the second to have affected the airport, employees said. On the previous day, two balloons were also detected within the airport precincts. Although there were no serious accidents, civil aviation was disrupted causing a waste of manpower and other resources, the airport authority said.

Hydrogen balloons are usually released during celebrations. In most cases, there is no way for the meteorological authority to find the person who has released a balloon. Normally, hydrogen balloons cost about 200 to 300 yuan a piece.

Once released, hydrogen balloons can fly to altitudes between 10,000 to 15,000 meters in the flight paths of civil aviation aircraft, said Tian Helin, a department chief with the Shenzhen aviation administration station. "An aircraft can fly as fast as up to 300 meters a second. Once a giant balloon collides with an aircraft or the balloon is sucked into the engine, the plane will crash and passengers will be killed," Tian said.

To safeguard the operations at the Shenzhen airport, two-thirds of the area in Shenzhen, including Bao'an and Longgang districts, have been designated as off-limits to balloons.

In September, the municipal meteorological observatory turned down a request by a government agency to release several giant balloons during a national flag-raising ceremony at the Citizen's Center on Oct. 1. In December last year, Vice Mayor Lu Ruifeng stopped the preparatory committee for the 2011 Summer Universiade from releasing 100 balloons at a ceremony held to welcome members of the appraisal team of the International University Sports Federation (FISU).