proportion of power required to sustain flight "will continue to make the units very expensive in first cost, relatively expensive in operating costs per unit mile and fraught with problems of dependability."

Regardless of their eventual place in commercial air transport, helicopters have great promise in surveying and civil engineering construction. They are already being used to a limited extent in surveying reconnaissance, in transporting survey parties to and from otherwise inaccessible points, and in other surveying operations; and their unique properties make them especially attractive for a variety of surveying applications. Although the helicopter's navigational requirements might seem to be somewhat similar to those of other types of low-speed, lowaltitude aircraft, they will create a special problem in those areas where both helicopters and fixed-wing aircraft operate because of the great differences in cruising and approach speeds, and they will probably require a considerably more accurate system of radio navigation than is available today. Cruising altitudes of large propellerdriven commercial aircraft averaged around 20,000 feet until the advent of jet propulsion when, with increased speeds and power, the cruising altitudes jumped to about 40,000 feet. Littlewood has said, "Once 30,000 feet operating altitude is exceededand exceed it we must for jet operations— the problems are largely ones of degree and not of nature. . . . It seems a reasonable conclusion... that the probable altitude range of efficient jet transport operations will lie between 30,000 and 55,000 feet."

CHARTING NEEDS OF AVIATION

If these appraisals for the future are accepted, then one may draw certain conclusions as to the charting needs of aviation. These conclusions are based on the three cardinal principles that should guide all chart producers. They can be stated in three words: utility, reliability, and availability. Each is an equally important link in the chain. Thus, a chart perfectly de6 LITTLEWOOD, WILLIAM: 16th Annual Wright Brothers Lecture, Washington, D. C., 1952.

signed for the need of a particular user and absolutely accurate and current is of no value whatsoever to that user if it is not available when and where he needs it. Alternatively, 100 percent availability of charts that are wholly unreliable or illegible could be even worse than no charts at all. Utility, or the use for which the chart is designed, usually establishes the scale and size of sheet; the scale in turn controls the amount of legible material that can be shown; and in my view, legibility demands simplicity. Reliability calls for accuracy and "up-to-dateness." Availability depends on the efficiency of the distribution system, and the systematic publication of when and where the latest issues are obtainable.

On these bases it is reasonable to conclude that something like the present radiofacility charts issued by the Department of Commerce will predominate for some time, but that a navigational need will continue to be felt for such basic charts as the Sectional and World Aeronautical Charts at the scales of 1: 500,000 and 1: 1,000,000, not only to fill the requirements of the slow and intermediate speeds and ranges, but also the requirements of aviation training, planning, and development. Most of the high-speed, long-range aircraft, however, will be better served by a scale of about 1: 5,000,000. Speed, altitude, range, and the need for more nearly continuous positioning argue for a considerably simplified cartographic style.

On cartographic style, I have few personal observations. Much effort has been devoted to portrayal of topographic relief for aeronautical charts. During the past three decades almost every conceivable combination of contours, gradient tints, hill shading, spot elevations, and even perspective sketching have been tried in the United States and other countries.

I admit some personal contributions to the confusion on this subject in years now passed. At this time, and from a somewhat more detached perspective, my present conclusions are that contours on aeronautical charts of scales of 1: 500,000 and smaller are unnecessary, if not useless; hill shading

is simply an expensive delusion not worth the cost; and that the most satisfactory combination for the pilot and navigator is, and will continue to be, a simple arrangement of hypsometric tints (without contours) with a judicious but generous use of spot elevations. The reasons are simplicity and economy of production and legibility for the user.

The pilot who flies only in clear weather has quite a different need from those who are fully equipped for instrument flying. The number of aircraft not so equipped is steadily decreasing. In the United States, as in Europe and some other parts of the world, air-traffic control is becoming an increasingly acute problem. The result is a demand for reliable positioning of all aircraft at all times--not just in times of low visibility as in the past-and thus an increased need for more accurate knowledge of obstructions and air-traffic aids, all of which depend on accurate basic surveys.

Some kind of positive and simplified airborne device like the pictorial computer which will indicate the aircraft's position continuously or at very frequent time intervals seems to be the answer. A number of studies and trials are being made of automatic position-indicating devices in the United States and elsewhere, but no wholly satisfactory system that will do this has yet been put into wide use. It seems that it will be only a matter of time before it will. Future plans for a system of radio air-navigation aids common to the various civil and military services include such an arrangement. This is already regarded as a necessity by a number of air-transport operators. The system will have to be based on the bearing-distance principle, (e.g., the VORDME system) on which the present U. S. system of aids has been built.

On this subject the Administrator of Civil Aeronautics has recently said, "The needs for the future include provision of pictorial or symbolic presentations for giving instructions to the pilot or displaying his position, and equipment for keeping 50 or more aircraft under control in the same area. . . . Improved displays showing not.

only aircraft near an airport but enroute from one airport to another are scheduled for development and evaluation. The pictorial display, it is believed, will replace much of the information which traffic controllers now maintain on paper slips, and simultaneously reduce the communcations load imposed by pilot position reports." It is almost needless to say that the introduction of such devices will have a profound effect on the aeronautical chart of the future in all its forms, but the cardinal principles-utility, reliability, and availabil ity-will still apply.

WHO OWNS THE AIR SPACE?

The surveyor will always be concerned with problems of delineation of property and boundaries, and the legal documents and decisions that affect his work. Increasing air traffic over densely populated areas brings up a number of new questions in air law and property rights. Who owns the air space, and to what altitude? When and under what conditions does flight over private property constitute trespass? To what extent is the aircraft operator liable for damages to people and property on the surface? In recent years a number of courts have handed down judgments on such ques tions relating to ownership of the air space. Although in the realm of speculation, they could, in the foreseeable future, raise some interesting and unique problems for surveyors. I am not aware, however, at this time of any specific cases that have involved

surveyors.

AIRBORNE SURVEYS

Remarkable advances have been made in aerial surveying (including aerial photogrammetry) contemporaneously with the availability of more suitable aircraft for the job. The aerial surveyor already has a wide range of aircraft types for his possible needs. He will have an even wider choice in the future. Speed and altitude performance is

7 HORNE, C. F.: "Air Navigation Aids and Air Traffic Control," Amer. Inst. of Elec. Engrs Dec. 9, 1952.

most important in this respect; and the helicopter widens his choice.

The early tests of aerial geophysical reconnaissance and exploration are promising, and also in these fields a wide range of performance is available.

The feasibility of determining the geographic positions of points on the earth's surface through the use of such devices as Shoran with aircraft has been demonstrated and applied. One of the most extensive of such projects is being carried out by our Canadian colleagues. 8

In short, there will be increasing opportunities for applying already known physical and electronic devices to airborne use in surveying and mapping. Many new combinations will be tried. Those that are most acceptable will be the ones that offer greatest over-all practical economy-not necessarily those that may be most attractive in operational nicety.

SAFE AIR TRANSPORT

Safety in air transport is always of wide interest; and any treatment of trends in aviation, even one so sketchy as this paper, would not be complete without it. Safety of air transport should be coupled with regularity of service because a rigid adherence. to schedules in all kinds of weather, as in other forms of transport, usually entails additional risks. Alternatively, higher safety may be possible at some sacrifices in regularity.

The basic objective of the U. S. Civil Aeronautics Act is a safe, regular, and economical air-transport system which will be in the public interest, convenience, and necessity. Likewise, one of the basic aims of the Convention on International Civil Aviation is to "meet the needs of the peoples of the world for safe, regular, efficient, and economical air transport." The vast system of U. S. Federal Airways, the efforts

8 RANNIE, J. L.: "Shoran-Electronic Tool for Control Surveys and Mapping," Civil Engineering, A. S. C. E., Aug. 1950.

Ross, J. E. R.: "Shoran Operations in Canada," SURVEYING AND MAPPING, Oct.-Dec.

1952.

of the U. S. Civil Aeronautical Administration, and the U. S. Civil Aeronautics Board as the regulatory agency, are devoted to these aims. The International Civil Aviation Organization with 59 member states, and its permanent Council of 21 governments strive continually toward the objective of safety, regularity, and efficiency in civil aviation.

These efforts are bearing fruit. Scheduled airlines have greatly improved their safety records during the past two decades. The record of all domestic and international scheduled air services is now down to about 1.3 passenger fatalities per 100,000,000 passenger miles. The record of U. S. scheduled airlines for the calendar year 1952 was only 0.38 fatality per 100,000,000 passenger miles-the best ever achieved in the United States. (In 1938 it was about 4.5.) In the same period (1952) the volume of air traffic reached a new high. The U. S. domestic airlines. were, as of January 1953, scheduling about 1,900 flights every day, making about 13,000 take-offs and landings daily. On February 11, 1953, they completed a full year without a single passenger fatality. During this record year they carried over 25,000,000 passengers a total distance of 13 billion passenger miles.

There is no simple way to state an index of regularity. Although it must be coupled with safety, it is right and proper that first emphasis is always on safety. Reliability of scheduled air services has steadily improved over the past decade. General Milton W. Arnold, Vice President of the Air Transport Association, has pointed out that during 1949, the U. S. scheduled airlines completed nearly 98% of the total scheduled mileage, and more than 99% for 6 consecutive months of the same year. His analysis also showed that during the previous 4 years flight concellations had been halved. This improvement in dependability accompanied

9 ARNOLD, GEN. MILTON W.: "Post War Progress in Scheduled Airlines' Safety, Regularity and Air Lift Potential 1946-1950 Inclusive," April 10, 1951. (Talk before The Press Wings Club, New York City.)

M

APS have an increasingly significant role in the modern world. We are daily being made more aware of the interrelation of maps and world affairs. This map consciousness has developed with the realization that, aside from their military importance, adequate maps provide the information required for the rapid economic and industrial development required by the free world today. The need for these maps is brought into sharp focus at this meeting for the Congress has, very appropriately, selected for its main theme: "Surveys and Maps Provide the Engineering Information Essential to Economic Planning and Development."

Some typical examples of development projects that have become increasingly important internationally are: Domestic and industrial water supply; flood control; irrigation; agricultural development; soil utilization and land improvement; mineral and fuel development; power development; development of energy resources; navigation; road and railroad design and construction; and many other public and civil works. There is an expression that very aptly describes the value of maps in military operations: "An Army without maps is an Army without eyes." It can be applied very appropriately to any program involving economic planning and development, for without the proper maps any such program is almost certain to wind up in a blind alley.

NEED FOR JOINT EFFORTS

The free nations of the world are acutely aware of their interdependency and fully realize the need for international cooperation in those matters that affect the wel

Presented at the Thirteenth Annual Meeting of the American Congress on Surveying and Mapping at Washington, D. C., March 23-25, 1953.

fare and security of any one of the nations. As the all-important map represents one of these critical elements, international cooperation in mapping is not only desirable but is an urgent necessity.

The United States has long recognized the international aspect of mapping and the need for joint efforts. In the year 1904, President Theodore Roosevelt extended welcome to the Eighth International Geographic Congress which convened here in Washington. This Geographic Congress was devoted to spreading geographic and cartographic knowledge throughout the nations of the world. It is of interest to note that the goal we are trying to attain in international cooperation was envisioned by Admiral Robert E. Peary in a paper delivered before the Eighth International Geographic Congress. He said: "The meeting of this congress in the United States holds great possibilities of good for us by bringing us into direct contact with the work of our colleagues of other countries. I earnestly hope that this session of the congress will prove a great and lasting stimulus to the interest of our people in geographic and allied research." These words are as topical and current today as they were half a century ago.

The cartographic sciences have been aided immeasurably by the many and varied contributions made by the Eighth International Geographic Congress. What probably constitutes one of the most valuable contributions to cartography, however, occurred earlier, in 1891, on the occasion of the Fifth International Geographic Congress, when proposals were first advanced for an International Map of the World. This new mapping concept envisaged the compilation of a map of international scope, with uniform scale, legend, and projection. The success of this undertaking is attested by the many maps already produced by the 35.