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How the upper air of the North Atlantic is charted

Caledonia, the Imperial Airways flying boat, is driven by four Bristol Pegasus Xc engines

LINKING EAST AND WEST. Caledonia, the Imperial Airways flying boat, is driven by four Bristol Pegasus Xc engines, each of 790 horsepower, at 2,600 r.p.m., at 5,500 feet; the engines are fitted in the wings. She has a maximum speed of 200 m.p.h. and a cruising speed of 164 m.p.h., a wing span of 114 feet and an overall length of 88 feet. A high-wing monoplane, she has special fuel tanks which give her a range of 3,300 miles. She has two decks, with lounges and sleeping accommodation for sixteen passengers.

A FEW years ago the Air Ministry sent out an exploring party. It had no provisions, no bulky kit. It went no farther than Croydon airport, yet it was one of the most important explorations carried out in [the twentieth] century.

The leader was C. F. Peters, one of the leading meteorologists in the world. Detailed from duty at the Air Ministry headquarters, he had gathered round him a group of University graduates, all of whom had obtained an Honours degree in Mathematics or Physics, or in both.

Their work was the beginning of a minute survey for the transatlantic flying boats and Pan American clippers which began their experimental flights between Foynes, Eire, and Botwood, Newfoundland, in the summer of 1937, flights which astonished the world by the comparative ease with which they were accomplished. Pilots, crews, engineers and designers justly received the publicity and the credit, but these men were the first to acknowledge the debt they owed to the meteorological men who explored the upper air of the Atlantic.

For years many people have wondered at the long and stubborn resistance of the Atlantic to all schemes for a regular transatlantic flying service. It is nearly thirty years since the first flight of an aircraft rising from the water - the frail stripling that has grown into the powerful flying boat of today. And it was in 1919 that two Englishmen, Alcock and Brown, closely followed by the crew of the airship R 34, proved that the Atlantic could be flown by aeroplane and airship.

Later pioneers - Lindbergh, Kohl, von Hunefeld and Fitzmaurice, Costes and Bellonte, Amelia Earhart, the Mollisons and others - made Atlantic flying almost a commonplace, but the idea, of a regular mail and passenger service that would leave and arrive to a fixed schedule remained a dream. Long ago we had the men, superbly qualified aviators and navigators; and more recently we had the machines. The unexplored upper air of the Atlantic had held back any scheme. That alone was the unpredictable factor. The winds, clouds and air currents, the vagaries of temperature and precipitation and wind velocities in those upper regions remained, as it were, dark secrets of an unexplored continent.

Before a scheduled flying service could be established in that wilderness of weather, the surveyors had to begin work - the meteorological men who deal not with valleys and mountains and plains, but with the behaviour of winds and clouds and rain in all their caprices.

When the Croydon “expedition” began work, its task was to draw up, in a multitude of graphs and mathematical timetables, a history of the weather over the Atlantic for the previous twelve years.

A mass of unrelated material lay ready to hand - weather logs from hundreds of ships, weather reports from hundreds of meteorological stations on either side of the Atlantic and on the Continent, thousands of statistics relating to the birth and death of depressions, the movements of Polar air currents, rainfall, snow, fog, dense cloud, the influence of the Gulf Stream and of the ice fields.

Slowly, that great weather history was written. Month by month the weather charts for those past years were filled in with ever-increasing detail. Lack of information left gaps in some of them - even today the whole of the upper Atlantic cannot be charted because there are parts of the sea beneath those weather areas from which no ships send weather reports; yet a survey of past weather was completed.

These experts had to investigate the weather of years past, because it was essential to know something of the average weather conditions over the Atlantic for a period of years, and to know the worst as well as the most favourable weather likely to be encountered in any month. That is precisely the knowledge they gained. At the Air Ministry is a series of mathematical tables. They could all be set upon two pages of foolscap, yet they represent two years’ research by the Croydon authorities and the distilled wisdom of a dozen years of meteorological knowledge of the Atlantic airs.

These statistics were “ghost” timetables of a theoretical air service. They showed the times it would have taken an aircraft at a known speed to have crossed the Atlantic at any date throughout those past years, the times based on accumulated data of weather, headwind velocities, storm areas and other factors that would have been encountered on that date.

They showed the best and the worst conditions a pilot might anticipate at any given date. They showed, for instance, that an aircraft with an air speed of 150 miles an hour flying from Foynes on the Shannon in Eire to Botwood in Newfoundland in the month of January could expect to be in the air - at the worst - 22·2 hours, and at the best as little as ten hours. If any proof of their accuracy were needed, it was confirmed on September 28, 1937, when Captain G. J. Powell flew the flying-boat Cambria from Botwood to the Shannon in 10 hours 33 minutes - a record trip. These statistics proved that, on an average of five years’ readings, the best months for transatlantic flights are from April to September. During that period reduced headwinds would enable a machine with an air speed of 150 miles an hour to cross from east to west in about fourteen and a half hours; it could expect to take at least an hour longer between October and January.

Against this, the charts showed that in several years the winter months can compete with the best of the summer periods; thus, there have been weather conditions in December, January and March so favourable as to enable a crossing to be made in from ten to ten and a half hours.

Observations from Ships

Mr. Peters and two picked assistants moved over from Croydon to Foynes and installed themselves in a room of a hotel. In another room was a complete radio equipment. Elsewhere there was a control room, where the work of this strange outfit - the first “signal box” of transatlantic flight - was coordinated.

Here, in this small wing of the hotel at Foynes, the work of the meteorologists was intensified. Every hour of the day the radio room searched the Atlantic for items of weather news, picked up ships’ messages, made contact with Botwood, and received weather reports from many parts of the world.

Invaluable news was supplied by one of the Air Ministry’s own meteorologists who lived on board a vessel making regular trips between Manchester and St. John’s, Newfoundland. His equipment, in addition to the ordinary instruments for checking temperature, humidity, barometric pressure, wind direction and force, included a stock of balloons, cylinders of hydrogen and a special theodolite. At intervals he released a balloon which was filled with a fixed quantity of hydrogen so that its rate of ascent - 500 feet a minute - was constant. By timing, the observer knew the height of the balloon at the end of each minute; and by observations through the theodolite he was able to calculate the direction and speed of the wind that assailed the balloon at various heights.

Atlantic weather forecasts

IN THESE PROSAIC BUILDINGS, the wing of a hotel (lower photo) at Foynes Eire, the meteorologists are in constant touch by radio with the flying boats. Every piece of information likely to help the pilots to check their position goes out from these buildings, so that if the aircraft are flying through cloud or in darkness and cannot take readings from the stars, they can “talk” to Foynes, which “nurses” them through the bad patches. The radio apparatus at Foynes is in the hut shown above.

His findings were flashed to the Air Ministry and to Foynes, and proved to be clues of outstanding importance. Today, as the mass of weather intelligence reaches the radio room, it is handed to the meteorological men, swiftly decoded - all weather news is in code for the sake of brevity - and transferred to charts. Each chart is a plan of the weather at that particular hour, as complete as the available information allows. The early charts show many blanks. As the day advances, however, and the weather bureaux of the world send out information, undulating lines (isobars) and concentric circles (depressions) begin to span the map of the Atlantic. Pin points, representing ships at sea, each with figures inscribed against it, begin to dot the white spaces. By evening the full story is told, and to the men at Foynes the tale is clear. What the weather is doing, and its tendencies for the morrow, can be read.

Such work is the daily routine of the Foynes station. Let us see it in operation in the hours before one of the flying boats is due to leave for Botwood.

The excitement begins when the commander of the flying boat gives the word. “We leave in twenty-four hours,” he says. By short-wave transmission Foynes and Botwood exchange local weather news. Throughout the twenty-four hours the charts take shape. As the evening draws near, the meteorological room assumes some of the excitement of a newspaper approaching press-time. Late news is swiftly absorbed into the body of the final chart. Last deductions are made.

Up the quiet village street walks the commander of the flying boat for a last inspection of the weather charts. He glances at the latest graph.

Last-Minute Alterations

“Looks good,” he says; “average headwind of 20 miles an hour. Low clouds and rain for first 500 miles, then clearing, and dropping wind. Nasty spot 800 miles out - might climb over it. Forty-mile headwind here. How’s that going to affect running time?”

They wrork it out. Air speed known; headwinds to be accounted for; possibly a detour to avoid storm area.

“We should be across in sixteen and a half hours,” he says, as he shakes hands and strolls away.

He has gone, but soon the voice of his machine speaks to the Foynes station from over the Atlantic. The radio room is at its peak moment. The flying boat reports her position, height and weather conditions. Foynes makes a rapid check, advises the flying boat that she has drifted slightly south of her bearings. The drift is adjusted.

In the meteorological room, the weather reports from the flying boat are checked with the forecasts. They are gratifyingly accurate. The weather men, however, are still scouring the Atlantic for further news, ready to flash to the flying boat any last-minute alterations in weather tendencies. .

Past four in the morning the Foynes men are still at work. The flying boat is in contact with Botwood station and is being “nursed” to safety on that side, but Foynes is already in touch with the Pan American clipper which is making a west-to-east flight.

Tension eases in the meteorological room. Morning comes, and there on the pale horizon is the growing speck which is the clipper.

Then, in the radio room, comes the triumphant message. The flying boat has reached Botwood, and the commander sends his thanks for the invaluable work of the men at Foynes.

THE PILOTS’ CABIN of the Imperial Airways flying boat Cambria

THE PILOTS’ CABIN of the Imperial Airways flying boat Cambria, which in September 1937 flew from Botwood to Foynes in 10 hours 33 minutes. This was a record trip. The rapid advance in flying times has been materially helped by the accuracy with which the meteorologists can forecast the weather and inform the pilots of any sudden change in conditions.

You can read more on “How Maps are Made”, “Reading Weather Charts” and “Sounding the Skyways” on this website.

Atlantic Weather Reports