XN000022-1983-08-03 — Page 3

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WEDNESDAY, AUGUST 3, 1983

HE SAID THAT ALTHOUGH THE RESULTS OF THIS AVIATION CONSULTANCY WERE DISAPPOINTING, THE FIRST DUTY OF GOVERNMENT MUST BE FOR SAFETY BOTH IN THE AVIATION AND THE MARINE CONTEXT. GOVERNMENT HAS BEEN STUDYING ALTERNATIVES, AND THESE INCLUDE THE POSSIBILITY OF A SUBMERGED TUBE TUNNEL IN THE EASTERN HARBOUR, AND THE FURTHER EXAMINATION OF ADVANCED ELECTRONIC AIRCRAFT LANDING SYSTEMS WHICH MIGHT PERMIT A BRIDGE TO BE BUILT AT LEI YUE MUN AT A LATER DATE.

THE SECRETARY SAID THAT THE ACCEPTABILITY OF A BRIDGE AT LEI YUE MUN DEPENDS ON THREE CONDITIONS BEING MET FIRST, THAT THE INSTRUMENT LANDING SYSTEM SHOULD BE ABLE TO OPERATE SAFELY AND WITHOUT UNDUE INTERFERENCE; SECOND, THAT GOVERNMENT MUST MEET INTERNATIONAL SAFETY AGREEMENTS FOR AIRCRAFT TAKING OFF IN RESPECT OF OBSTACLES IN THE TAKE OFF PLANE; AND THIRD, THAT THE HEIGHT CLEARANCE NECESSARY FOR SHIPPING USING THE LE YUE MUN CHANNEL TO ENTER THE VICTORIA HARBOUR MUST BE ACCEPTABLE EN MARINE SAFETY AND ECONOMIC TERMS.

THE SECRETARY WENT ON TO EXPLAIN THAT THE TWO MAIN CONSTRAINTS WERE THE PRESENT INSTRUMENT LANDING SYSTEM, WHICH IMPOSES A MAXIMUM OVERALL HEIGHT OF 36.8 METRES ABOVE P.D. FOR ANY BRIDGE- AND THE INTERNATIONAL AVIATION SAFETY REQUIREMENTS FOR THE OBSTACLE LIMITATION SURFACE* INDICATE A MAXIMUM OVERALL HEIGHT FOR THE BRIDGE OF 58 METRES ABOVE P.D. NATURALLY, THE MORE THE BRIDGE IS MOVED TOWARDS THE WEST. THE LOWER WILL BECOME THE PERMISSIBLE HEIGHT FOR SAFETY REASONS.

WHILE THESE STUDIES WERE GOING ON, A FURTHER DEVELOPMENT HAS TAKEN PLACE IN THE FORM OF NEW MARĪNE INTERNATIONAL CONVENTION REQUIREMENTS WHICH WILL BE INTRODUCED IN OCTOBER 1983. THESE REQUIRE SEGREGATED BALLAST FACILITIES FOR OIL TANKERS, AND WILL INCREASE THE DIMENSIONS OF ALL PETROLEUM PRODUCTS TANKERS OVER 30 000 TONS. THIS WILL INCREASE THE MARINE CLEARANCE REQUIRED FOR SUCH SHIPS FOR ANY BRIDGE AT LEI YUE MUN.

THE DIRECTOR OF MARINE ESTIMATES THAT THE BRIDGE

WOULD REQUIRE A GREATER MARINE CLEARANCE TO ALLOW SAFE PASSAGE OF THESE NEW TANKERS, RESULTING IN AN OVERALL HEIGHT OF AT LEAST 61 METRES, PERHAPS AS MUCH AS 67 METRES ABOVE P.D.+.

IN THE FACE OF THESE PROBLEMS, GOVERNMENT HAS LOOKED INTO THE POSSIBILITY OF MORE ADVANCED INSTRUMENT LANDING SYSTEMS.

TWO SYSTEMS HAVE BEEN CONSIDERED FIRST, AN M-ARRAY GLIDE PATH SYSTEM (MAGPS); AND SECOND, FOR THE LONGER TERM, A MICROWAVE LANDING SYSTEM (MLS).

MAGPS SYSTEM IN ORDER TO TEST WHETHER AN MAGPS SYSTEM

WOULD BE COMPATIBLE WITH A BRIDGE AT LEI YUE MUN, IT WOULD BE NECESSARY TO INSTALL THE ACTUAL SYSTEM ON A TEMPORARY BASIS. THE SYSTEM WOULD HAVE TO BE FLIGHT-TESTED UNDER REAL CONDITIONS. IN ADDITION, A STUDY WOULD HAVE TO BE CARRIED OUT ON THE POSSIBLE EFFECTS OF VARIOUS BRIDGE DESIGNS BY MEANS OF A MODEL, AS WAS DONE FOR THE EXISTING INSTRUMENT LANDING SYSTEM.

THE DIRECTOR OF CIVIL AVIATION CONCLUDED AFTER CONSIDERING EXPERT ADVICE, THAT IT IS NOT AT ALL CLEAR THAT THE MAGPS SYSTEM WOULD BE A SUITABLE OR EFFECTIVE SOLUTION, AND WE COULD ONLY SPEAK IN TERMS OF REASONABLE PROBABILITY THAT IT WOULD IN FACT WORK+ IN THE LIGHT OF THIS. THE GOVERNOR IN COUNCIL RULED THAT FURTHER WORK ON THE MAGPS POSSIBILITY SHOULD NOT BE CONTINUED BECAUSE OF :