© Wonders of World Aviation 2015-24  |  contents  |  site map  | contact us  |  cookie policy

Wonders of World Aviation

Mobile Site

Extensive preparations are made to remove hazards from first flights over new sea routes by Pan American pilots

THE BERMUDA CLIPPER being prepared at Port Washington for a survey flight

THE BERMUDA CLIPPER being prepared at Port Washington (N.Y.) for a survey flight between New York and Bermuda. The route between these two places was surveyed jointly by Pan American Airways and by Imperial Airways. The New York-Bermuda survey flights, which proceeded exactly as planned, were in the nature of a preliminary investigation for the transatlantic flights made in 1937.

THE commercial pilot and the commercial aviation company do not refer to “pioneering” or “trail-blazing” with reference to a new aerial route. They prefer the less colourful term “survey flight”. They take the attitude that it is no more remarkable than any other flying job. Perhaps conclusive proof of this is the fact that in the United States, the home of publicity, few newspaper accounts of any importance appeared for the three years during which preparatory work was done on the California to New Zealand route across the Southern Pacific.

Yet, for all its careful calculations, the making of a new air line route, especially across great oceans, is a work also of adventure — a nice blend of romance and science.

Pan American Airways were on the verge of inaugurating the regular mail and passenger services across the Pacific to Manila (see the chapter “Across the Pacific”), when the announcement was made that one of the Pan American clippers, a big Sikorsky, specially built for the Pacific run, would make the first through flight from the West Coast to New Zealand and back. This was the climax to years of careful and unadvertised work. A study of those years is informative. The first consideration was the commercial potentialities of direct flight from America to Australia. A prime factor was the reorientation of transport facilities which followed the development of air routes from Europe to Australia. Before that time the fastest means of travel between London and Sydney had been to take ship to New York, train to San Francisco, and a second ship to Sydney.

With the beginning of world air services the position was reversed and it became quicker to travel from the United States to Europe and thence by aeroplane to Australia. Obviously, then, in view of the importance of trade between the U.S.A, and Australasia, a direct air line would have sound commercial prospects.

The American Government and American business institutions were aware of the need. A positive step was the colonization of Howland, Baker and Jarvis Islands, in the Southern Pacific, by the U.S. Department of Commerce. Pan American Airways decided to undertake a close examination of the project. The first document in the firm’s files on the subject is dated January 9, 1933. It is an analysis of Australasian trade and transport conditions at that time and a summary of how they would be affected by the then projected extension of European air services into the area.

The next significant date is March 12, 1934. It was then that the China Clipper route and bases were chosen. At the same time serious survey work on the New Zealand service was put in train.

The preliminary measures were taken in the Pan American office. Research was carried out by weather, radio and “operations” experts, who analysed and reported on specific problems to be solved. Meanwhile individual engineers travelled, by whatever ships were available, across the Southern Pacific, studying conditions and such islands as were visited.

In 1935 a full-scale expedition set out in a private vessel. The expedition’s task was to make complete marine and weather surveys of many islands between Samoa and New Zealand; and to recommend sites for flying-boat bases, weather observation posts and radio stations, both for communications and for direction finding.

There followed two years of solid research. A number of expeditions was sent out. Specialists took station at various recommended bases and conducted detailed studies of the water, and of the weather and winds from the surface up to 25,000 feet.

Finally, for the three months before the clipper went through on its survey flight, in the spring of 1937, bases with complete staffs had been set up and were working a daily routine just as though the regular service had already begun.

It was thus that the route was charted which the Pan American clipper flew over on its survey flight of March 1937. The first leg of the flight, as far as Hawaii, had already been surveyed in the preparation for the China Clipper service, for the two routes run parallel over this section (see the chapter “Across the Pacific”).

This survey flight broke no records, and was not intended to break records. It was to fill in, with flying experience, such gaps as might remain in the data which had been compiled over the previous years. Where no such gaps existed the object was to test, in practical form, the theories evolved by surface study. Another task, and it is here that lay the element of the hazard, was to

test the flying aspects of the temporary bases which had been set up.

The route finally chosen was from San Francisco to Hawaii, thence to Kingman Reef, on to Samoa and so to Auckland, New Zealand.

On the way to Hawaii the experts began their studies of the flying conditions, even though this part had already been so fully surveyed. Pan American had already flown this route ninety-five times, but much new information was amassed by the crew of the Sikorsky. They took measurements of wind shifts and humidity at varying altitudes and observations on cloud mass.

Snowstorm Near the Equator

From Hawaii onwards, the flight plan laid down mainly “route exploration” as the objective on the southbound flight, and “transport routine experiment” for the return trip.

The first stage, to Kingman Reef, was a fine example of aerial navigation. Kingman Reef is not only, as its name implies, a coral-reef atoll; it is also one of the smallest charted islands in the Pacific. Geographically, its situation was considered ideal for the projected route and, as the island was too small for habitation, Pan American had posted a ship as a temporary base. This was fully equipped with radiotelephony and direction-finding apparatus and staffed in the same way as a land base.

The conditions for the flight there from Hawaii were distinctly unpleasant. The clipper encountered torrential tropical rain and at one point, only 200 miles south of the Equator, ran into a snowstorm. In an eight-hours flight only two sunsights were possible and three hours were spent flying blind on the instrument board. The radio direction-finding apparatus on board the floating air-base, intended for its most valuable application in just such a contingency, worked perfectly.

SHORT-WAVE AERIAL SYSTEM at the Pan American radio station at Honolulu

SHORT-WAVE AERIAL SYSTEM at the Pan American radio station at Mopaku, Honolulu. This is the point of divergence of the regularly operated route from San Francisco to Manila, in the Philippine Islands, and of the San Francisco to New Zealand route surveyed in 1937. The establishment and operation of radio stations is part of the preliminary work carried out before the first flights are made over new routes.

The bearings given brought the clipper first of all to an exact point ten miles from the reef. On arrival there, however, it was found that the whole area round Kingman was shut off by a tropical rainstorm. Direction-finding bearings were therefore given that took them round and into the lagoon on the heels of the storm. For accurate flying on instrument and radio equipment this achievement ranks high. Not only could no celestial navigation be undertaken, but also there was no possibility of flying low to pick up landmarks, because of the absence of land on that part of the route. The crew reported that the only object seen during the trip was an ocean tramp some 800 miles off Hawaii.

The next leg, 1,600 miles from King-man Reef to Pago-Pago, Samoa, gave the crew an even more exacting task. Again they met with rain and heavy cloud. The flight took ten and a half hours. For six of these hours the machine flew between two solid layers of cloud, below and above them. With again no opportunity to take bearings from the sun, they occasionally dived until within sight of the surface and dropped a glass “bomb” filled with aluminium-powder, on which to take a drift-sight.

Much of this section of the flight was carried out by radio. The crew, however, used the miniature direction-finding equipment installed in the aeroplane itself instead of depending on the reverse process of following signals from the surface direction-finding station.

In spite of the fact that the wind shifted at different times to more than three-quarters of the points of the compass, the crew succeeded in flying a bee-line course and to complete it one and a half hours faster than the schedule.

It was on this leg that the only unplanned event of the flight took place. The radio operator picked up a message from a ship, which had asked for assistance. The ship’s chronometer had stopped and the plotting of her course on the chart had therefore gone astray. The vessel was uncertain of her position. The clipper radioed her to stand by and gave a time signal at a predetermined second. The ships’ crew were thus able to set their chronometer.

The original plan had laid down that the clipper should fly on the following day from Samoa to Auckland, but weather conditions forced an alteration. Over this section of the course there had passed a cyclone, with its accompaniment of gusty wind, rain squalls and scattered cloud.

Helped by the Trade Winds

There are nearly a hundred islands between the Samoan Islands and New Zealand. It was important for the crew to be able to take observations on these islands, chart them correctly and log them as landmarks for future pilots flying a regular service. So the clipper was ordered to wait for more favourable conditions.

The fullest value was obtained from the survey flight on this third and last leg. In good visibility the crew were able to log principal features of all landfalls and to observe not only the islands themselves, but also the condition of the water round them. The pilot of a machine flying a regular service not only wants to know every recognizable feature of land he may cross, but also must be prepared in an emergency to make a safe forced landing. Hence the particular attention paid to water conditions by the clipper’s crew.

In addition, the clipper flew the course at many varying levels with a view to determining which would be the most satisfactory. On the edges of the trade wind zone, it was important to locate the major lines of wind shifts. The crew reported most comfortable flying on that part of the course where the trade winds blow, with steady air currents upon which the pilot could rely. The trade winds have thus proved themselves to be as much a friend of the modern clippers as of the old-time sailing vessels.

Other observations taken included dew point and temperature at all levels. In all, some eighty-six pages were filled with careful notes taken during flight. When the crew alighted at Auckland, the trip had been completed in forty-nine hours twenty-seven minutes flying time.

ARRIVAL OF A CLIPPER at Alameda, San Francisco Bay

ARRIVAL OF A CLIPPER at Alameda, San Francisco Bay, California after the completion of the first survey flight from San Francisco to Hawaii and back in 1935. The flight completed in seven days was over the first stretch of what was to be the San Francisco-Philippine Islands route. The regular service on this route was established in 1936.

An enthusiastic welcome awaited the machine, but the crew persisted in regarding the flight as a purely routine affair. The captain sent by radio a report in which he stated that they “had found no problems that had not been fully anticipated”. He added that there was nothing which the engineers had not previously encountered and which had to be solved before the clipper service could be established successfully across the South Pacific.

The captain admitted that weather conditions differed a great deal from those encountered on the northern route, but he drew the conclusion that they were similar to those of which Pan American had had full experience for ten years over the Caribbean Sea. Finally he considered a regular fifty-hours’ flying schedule between America and Australia to be a workable project.

To New Zealand the successful conclusion of the outward flight was of high significance. The institution of a regular service from the United States, in conjunction with the projected Imperial Airways service to Australia, is bound to make New Zealand one of the most important centres of world flying in the Southern Hemisphere. The arrival of the Pan American clipper brought this project within measurable distance. Already other Pan American air lines, of which two thousand miles are planned, were busying themselves with the elaboration of timetables to act as feeders to the Pan American and Imperial Airways craft.

The return journey, as far as Honolulu, Hawaii, was completed by the clipper in thirty-three hours thirty-three minutes’ flying time, although the aircraft took the trip at a leisurely pace and stopped at the two bases for longer than would a clipper in regular service. The object was to collect all the information available. From Honolulu, this particular machine’s trail-blazing activities were over, and she flew westward to Manila to take her place in the China service between there and Hong Kong and to be officially christened the Hong Kong Clipper.

Daily Flight Routine

Within a month Pan American Airways were inaugurating a fresh series of survey flights on the Bermuda run; later the survey flights over the transatlantic route were completed. The Bermuda flights were expected to offer no great difficulties and such was the fact. The regular service from the United States to Bermuda, operated in conjunction with Imperial Airways, was brought into being by the end of the summer.

The main object of these flights, apart from the testing of radio aids and port facilities, was to chart sea, air and weather conditions from sea level up to 20,000 feet. As early as 1931 Pan American technicians had estimated that the flight time from New York to Hamilton (Bermuda), approximately eight hundred miles, would be five and a half hours. But the clipper, aided by tail-winds, completed her first trip out in four hours forty-five minutes, and the return trip, in unfavourable conditions, in six hours nine minutes. The Cavalier, of Imperial Airways, left Hamilton the same day and reached New York in five hours forty-five minutes; the return trip was made in much the same time as that of the clipper. Thus, upon an average, the six-years-old estimate was remarkably accurate.

As with the New Zealand route, the weather service and radio aids at both ends worked daily flight routines for thirty days before the flights were made. These arrangements were found to work well.

The completion of the clipper’s survey flight from San Francisco

IN AUCKLAND HARBOUR, NEW ZEALAND, on the completion of the clipper’s survey flight from San Francisco. Experts who travelled in the aircraft decided that the ground stations and knowledge of weather conditions available were satisfactory for the inauguration of a regular service After the survey flight the clipper was renamed the Hong'Kong Clipper and was used for the China extension of the San Francisco Manila route across the Pacific Ocean.

One aspect of the surveys was to test the port facilities not only at Port Washington (New York) and at Darrell’s Island (Hamilton), but also at Baltimore, south from New York on America’s eastern seaboard. It was realized that the temporary base at Port Washington would not be suitable for winter operation (eventually the service will operate from a new airport under construction at North Beach). Baltimore, having been tested thoroughly, was chosen for the winter base. The clipper now flies from Baltimore to Port Washington and then to Bermuda. These Bermuda survey flights went so much “according to plan” that they approached the commercial pilot’s matter-of-fact ideal.

The transatlantic survey flights of 1937, for which the Bermuda flights were in the nature of a rehearsal, are a familiar subject. Yet certain aspects of this trail-blazing programme are worthy of note here.

The route surveyed in the summer of 1937 is by no means the only one which has been considered by Pan American Airways. In all they specify six more or less “flyable” courses to Europe; New York—Bermuda—Azores—Portugal; New York—Botwood (Newfoundland)—Foynes—Southampton; New York—St. John’s (Newfoundland)—Azores—Portugal; New York—Botwood—Azores—Portugal; New York—Shediac (Canada)—Cartwright (Labrador)—Foynes— Southampton; NewYork—Greenland—Iceland—United Kingdom.

The first and second of these courses were chosen as being the most practicable for modern commercial aeroplanes of a long range and as the most economical route for a paying service between the British Isles and the North American continent.

The general impression after the first survey flights of 1937 was that the future transatlantic route, in summer, would be via Botwood and Foynes, but that in winter the line New York-Bermuda-Azores-Portugal would be more practicable for first services. Time and greater knowledge of transatlantic flying conditions may serve to alter these conclusions.

The matter-of-fact attitude of the commercial air pilot to these “trail-blazing” flights was illustrated to perfection in the summer of 1938, by the reports from the Mercury, the upper component of the Short-Mayo composite aircraft, in her record-breaking transatlantic flight.

Accurate Weather Forecasts

The Pan American attitude is exactly the same. In an official description of the first flight by the Pan American clipper the following passage occurs:

“As a marine transport operation, the Atlantic Ocean simply represents a nonstop flight of two thousand miles. It represents substantially the same transport operating problems that the California to Hawaii crossing represents (except that the Pacific stretch is twenty per cent longer).”

The purpose of these survey flights, as of others, was first to test the elaborate system of weather forecasting which had been prepared and estimated from surface weather maps dating back fifty years; and, secondly, to test base facilities.

There was a notable difference between the flights of the Imperial Airways machines and those of the clippers, in that the clippers, save on one trip, flew at much greater heights. This is part

of Pan American’s policy which obtains throughout its services and may be attributed to the successful establishment of high-altitude flights in South America. The first eastward trip and most of the westward trips were flown at 10,000 feet and proved the accuracy of the weather experts’ forecasts.

One experiment was made in lower-altitude flying on the second westward trip. On this trip, for most of the way, the clipper stayed below 1,000 feet to study surface conditions and to estimate if possible the relationship between weather conditions above and the water below. The crew were in or below cloud most of the way and flew on instruments ninety per cent of the time.

An excellent example of weather reporting efficiency occurred on the flight. Five hundred miles from Newfoundland Banks the crew received a radio weather report from Port Washington telling them that within fifty minutes they would encounter a secondary “warm front” preceded by a wind shift; immediately beyond would be another secondary front of greater potentiality; and finally a “cold front” of high concentration striking right across the course. These exact conditions were met with in precisely the time and degree forecast. The test for the weather service was a severe and practical one.

If the surveying aircraft had been on a regular schedule flight, ample opportunity would have been provided to avoid the bad conditions. As it was, the clipper flew straight through the stormy patch to collect more data.

This clipper made a flight from Miami to the Virgin Islands and back in seventeen and a quarter hours early in 1935

LEAVING BISCAYNE BAY, MIAMI, FLORIDA. This clipper made a flight from Miami to the Virgin Islands and back in seventeen and a quarter hours early in 1935. The distance flown was about 2,500 miles. The flight was a test before the same flying boat set out on the first survey flight from San Francisco to Hawaii.

You can read more on “Across the Pacific”, “Pan American Airways” and

“Survey in the Empire” on this website.

Surveying New Airways