China's aviation administration will strictly limit the operation of passenger jets that are not equipped with a second-generation airborne collision avoidance system (ACASII) starting Friday.

The measure aims to decrease the possibility of jet collisions following the tragic collision last week in southern Germany between a cargo plane and a passenger jet.

A document from the General Administration of Civil Aviation of China (CAAC) said passenger jets without the ACASII system are not allowed to take off or land between 8 am and 9 pm at major domestic airports including Beijing, Shanghai, Tianjin, Guangzhou and Shenzhen beginning July 12.

Such jets will also be forced to fly below the attitude of 8,400 meters (27,559 feet) along some busy air routes.

The ACASII system alerts pilots to the presence of any transponder-equipped aeroplane in the vicinity and provides assistance in the detection and resolution of potential conflicts.

The equipment is designed to operate independent of ground-based systems used by air traffic controllers for the prevention of collisions.

The CAAC document said planes have increased dramatically in recent years and such conditions pose great difficulties to air traffic regulation.

The ACASII system would help correct the errors neglected by ground radar systems, and avoid possible collision tragedies, the document reads.

Statistics at CAAC show that most domestic airline fleets have the collision avoidance system, though some need to be upgraded. Some small planes, which operate for short distances, are still not equipped with ACASII.

China had promised in December 2001 that domestic commercial jets would be equipped with ACASII before 2004 to strengthen aviation safety, and had announced a concrete implementation schedule for it.

From January 2002, all turbine-powered aeroplanes that have a maximum certificated take-off mass in excess of 15,000 kilograms (33,069 pounds) or that are authorized to carry more than 30 passengers, must be equipped with an ACASII system.

Starting January 1, 2004, all turbine-powered aeroplanes that have a maximum certificated take-off mass in excess of 5,700 kilograms (12,566 pounds) or that are authorized to carry more than 19 passengers should follow suit.

(China Daily July 9, 2002)