Eyes in the Skies

Aerial map making is doing wonders in World War II. For example:

Allied commanders had set May 3, 1943 as the day for the climactic attack on Tunis and Bizerte. At the last moment there was a hitch: bad weather had grounded reconnaissance planes and there were no photographs of the enemy positions. The attack was postponed.

Three nights later, the needed pictures were in hand and Allied artillery opened fire on pinpointed targets. By morning, every enemy gun had been silenced. Many had received direct hits; none was missed by more than five yards. The Germans and Italians were so astonished at the gunners' accuracy that, according to prisoners, they thought a secret weapon had been used. Thanks to the reconnaissance pictures, resistance was so thoroughly crushed that the British First Army took Tunis in 24 hours with only 100 casualties.

This story was told last fortnight by a commander of U.S. flying cameramen, Colonel James G. Hall, to the American Society of Photogrammetry, convened in Washington. Photogrammetry is the name of the relatively new science of mapping by means of aerial photographs. The photogrammetrists (mostly servicemen) made many other eye-opening points:

> Since Pearl Harbor, U.S. airmen have photographed 8,000,000 sq. mi. of the earth's surface, an area twice the size of the U.S.

> One of the toughest jobs was to photograph Jap installations on Guadalcanal. From a base 900 miles away, against fierce air opposition, Navy photographers did the job so well that when the Marines landed on the island they knew the number of Japs and Jap planes there, the position of every major gun.

> On the morning of the Battle of Kula Gulf, Navy officers, aware that the gulf was full of dangerous coral reefs, ordered a quick chart. Such a job would ordinarily take at least three days. Army planes from Guadalcanal swarmed over the gulf, hastily shot 1,500 pictures covering nearly 500 sq.mi. In eight and a half hours the pictures were taken, developed, and assembled in a mosaic showing all the reefs. In the battle that night no U.S. ship ran aground.

> Tactical reconnaissance often goes on simultaneously with the fighting itself. In the invasion of the New Georgia islands, for example, airmen photographed the Jap lines and dropped their film to troops in the field, who developed and used them on the spot.

These are typical achievements of a group of flyers who have had much less attention than fighter and bomber pilots, but whose job is one of the most skilled and dangerous in the air. Addressing the photogrammetrists, Air Chief Henry ("Hap") Arnold observed that "often a camera mounted on a P-38 has proved of far greater importance than a P-38 with its normal complement of guns."

They Must Get Back. Unlike other flyers, reconnaissance pilots usually fly unarmed--and they must return from their missions. They generally take their photographs at very high altitudes (over 30,000 ft.). Both the U.S. and Royal Air Forces now assign their best planes for reconnaissance. The U.S. favorite is a stripped-down P-38, with five cameras in the nose instead of guns. The Flying Fortress, with eleven cameras, is also used, on less hazardous missions. The British use Mosquitoes and Spitfires. Military needs have fathered many innovations, such as flash bombs for night photography, a new camera with a strip of moving film for fast picture-taking at low altitudes.

The most important new invention is "trimetrogon" photography. This enables a flyer to photograph the ground below from horizon to horizon. The equipment consists of three cameras with wide-angle lenses, one pointing straight down and one obliquely to each side. By means of triangulation and ingenious translating devices, distortions resulting from the oblique angles are corrected in the final print. The trimetrogon method, by making it possible to space charting flights 25 miles apart instead of only four to six, has enormously accelerated mapping. Last fortnight its inventor, Lieut. Colonel Gerald ("Colonel Fitz") Fitzgerald, Chief of the Air Force's aeronautical chart division, a baldish, twinkling Irishman, was awarded the Sherman Mills Fairchild plaque for his achievement.

Reading aerial pictures requires even more skill than shooting them. The best interpreters can identify new types of aircraft on the ground, and name enemy ships, from a photograph with a scale of one to 10,000. They can often read bomb damage accurately from pictures taken six miles up. In Sicily, the Army found the photogrammetrists' interpretations 100% accurate.

Today air photography is considered so vital that the U.S. has 1,000 photogrammetrists compiling charts and several squadrons of flying cameramen (divided into strategic and tactical groups), while a third of the planes on every bombing mission carry cameras. Reconnaissance flyers, a cocky, confident group, like to quote a prewar prediction by German General Werner von Fritsch: "The military organization with the best aerial photo reconnaissance will win the next war."

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