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Aviation History
1946
1946 - 1594.PDF
I7O FLIGHT AUGUST 15TH, 1946 OVER the ANDES Planning the B.S.A.A, Buenos Aires —Santiago Extension By CAPT. DAVID BRICE, A.R.Ae.S. OF all the massive topographical features in the world,the Andes must be considered as one of the mostinimical to the interests of aviation. Stretching as they do, almost from the shores of the Gulf of Mexico, down through Venezuela, Ecuador, Peru, Colombia, Bolivia and Chile to Cape Horn, they present an almost unbroken chain some thousands of miles long. This great barrier, whose highest peak is over 23,000 teet, and whose breadth at one point is several hundred miles, naturally has a great influence on the entire meteoro- logical situation in South America. Paralleling the west coast, a mere 100 miles or so from the Pacific Ocean, the Andes effectively divide up the Continent, so that different types of weather system are to be found on each side Cold fronts which develop in the active storm areas south of Cape Horn frequently show a northerly trend and, with their western end trailing up the east side of the Andes, sweep up the coast through the Argentine, Uruguay and Brazil until they peter out in the tropical air of the Doldrums. These fronts, which are the cause of practically all the bad weather on the eastern seaboard, can reduce visibility and the cloud base below safe flying limits as far north as Rio de Janeiro, and thus have a great effect on all airline schedules. On the west coast, fronts which come in direct from the Pacific are liable to be impeded by the Andes, and until the frontal system has developed sufficient energy to scale the mountains, may blank out the towns in the foothills, and on the coast. Once they begin to cross the Andes the cooling effect is sufficient to cause blizzards and severe storms in the winter, and active cumulo-nimbus with their accompanying electrical discharges in the summer. As a rule these fronts are not very wide, and one may reckon that if the mountains are clear the west coast may be closed down, and, similarly, that if the mountains are obscured the coast will be clear. Unfortunately, like so many other meteorological rules, this one is by no means infallible. So much for generalizations. For many years now the Pan American associate com- pany, Panagra, has been operating a service from Buenos The only radio guide on the run between Mendoza andSantiago is a single M.F. radio beacon—known as Cristo Redentor—in the pass between Mendoza and Santiago. A good idea of the terrain over which B.S.A.A. must flyon the Andes service is given by this photograph of the Upsallata Pass through which the Panagra DC-3S must fly.The Lancastrians, which can cruise at greater operational levels, will not need to weave between the peaks. Aires to Santiago, the capital city of Chile. Equipped with DC-3S, this company was forced, by the comparatively low maximum operating altitude of these aircraft—about 19,000 feet—to seek some roundabout means of crossing the Andes, since the direct route passed over mountains well above 20,000 feet. That they succeeded in discovering such a route, and have managed to keep a service running under most difficult conditions, is cause for congratulation. Briefly, the Panagra route runs through a narrow pass, or rather a gorge, in the mountains from Mendoza in the east to a point just north of Santiago in the west. What such a trip involves can be imagined, when it is known that on the northern side is the mountain known as Cerro Aconcagua, which is 22,835 feet high. Whilst there is no doubt that this is an awe-inspiring trip, it is usually rendered most uncomfortable by the extreme turbulence which is produced by the very strong winds blowing through the gorge. These westerly winds, intensified by the funnel effect, can reach velocities of 60-70 knots quite easily, but seldom do the airlines operate through the gai^ if the wind exceeds 35 knots. It should not be imagined, either, that this is just a straightforward pass running from east to west, and a flight through it involves a fair amount of "weaving" between the peaks; indeed, from the east the entrance to the pass is completely obscured by mountains. Obviously, this can only be a fair-weather route, and cloud conditions in the pass automatically cancel all flight schedules. To enable accurate "actual weather reports" to be dispatched, a reporting station is situated in the gorge, and close by is an M.F. radio beacon. Operating under such difficulties it is not surprising that
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