DISPERSING FOG

Press, Volume CVI, Issue 31119, 23 July 1966, Page 1

DISPERSING FOG

Seeding Trial At Harewood Dry ice will be scattered over fog at the Christchurch Airport next year in an attempt to disperse the fog. This method, using crushed ice, dry ice or chemicals, is known as cloud seeding and has kept airports in the United States open on foggy days

It will be the first time such an experiment has been tried in New Zealand. Minutes after seeding, the fog usually begins to disperse. A standard spray aircraft, as used for top dressing, would be used for the experiment, said Mr C. H. Brazier, managing-director of Airwork (N.Z.) Ltd., last evening. At Portland The fog-dispersal technique is successfully used at Portland international airport, Oregon, and at Salt Lake City. When fog settles in a manner to keep an airport closed for a few hours a light aircraft carrying crushed ice takes off. With the assistance of radar for guidance over the runway the aircraft disperses the ice over the fog. Airport officials consider the fog-dispersal technique a normal operating expense, similar to snow removal.

The airport manager at Christchurch (Mr A. I. R. Jamieson) said the frequency of days when fog closed the airport for any length of time would probably not make such an operation a very economical proposition. “Our incidence of fog closures is not high when compared with what it is at some airports around the world,” he said.

Because all navigational aids were not fully operational at present “we could not give a light plane the ability to fly in the minimum conditions prescribed,” he said. Mr Jamieson said that all aids would have received operational clearances by the end of the year. Once this was so then the airport would be inclined to agree to the practicability of the project.

“Once the aids have all been declared safe by the Department of Civil Aviation we will certainly consider such remedial action for fog dispersal at Christchurch, even taking into consideration the low number of days when fog actually closes the airport for flying,” he said. “Quite Different" A meteorologist considered the fog closure situations between Salt Lake City and Christchurch to be quite different “Frankly I’m sceptical as to whether the clouddispersal method with crushed ice would work here,” he said. The fog at Salt Lake City or Portland, he said, was most probably radiation fog, which at best was only 6ft to Bft thick. At Christchurch fog several 100 ft thick was nothing unusual. He suspected that if the method did clear the middle of the fog belt, the cleared area would fill in again from the sides.