Aerodrome - United States

AERODROME - UNITED STATES Airport rating regulations of the U. S. Bureau of Air Com merce, as amended July 1, 1932, quotes the Federal law as fol lows : "The Secretary of Commerce shall by regulation * * * pro vide for the examination and rating of air-navigation facilities available for the use of aircraft of the United States as to their suitability for such use.

"The term 'air-navigation facility' includes any airport, emer gency landing field, light or other signal structure, radio direc tional finding facility, radio or other electrical communication facility, and any other construction or facility used as an aid to air navigation.

"The term 'airport' means any locality, either of water or land, which is adapted for the landing and taking off of aircraft and which provides facilities for shelter, supply, and repair of air craft, or a place used regularly for receiving or discharging pas sengers or cargo by air." The book of Airport Rating Regulations gives these definitions: Landing Strip.—A landing strip is an area at least 50o feet wide which forms part of a landplane airport, intermediate or auxiliary field, and which is suitable by natural condition or arti ficial constructure for the landing and taking off of aeroplanes under ordinary weather conditions.

Runway.—A runway is an artificial landing strip, or portion thereof, at least ioo feet wide permitting landing and taking off of aeroplanes under all weather conditions. A runway may be laid down upon a landing strip, but it need not cover the entire width of the landing strip.

Basic Requirements

of the U.S. Department of Commerce for all certificated airports and fields are : (I) Field or landing area; firm and approximately level with suitable approaches, well drained and without obstructions or depressions hazardous to taking off or landing; or at least two landing strips Soo feet or more wide crossing or converging at not less than 60° angles. These must permit safe landing in ordinary weather. If the sod or turf is not tough and hard enough for these purposes, the land ing strips must be of cinders, slag, gravel, asphalt or other suit able material; then they are called runways. (2) There must be a margin of at least ioo ft. clearance between the landing strip edges or runways and field boundaries. Surrounding obstruc tions are calculated to diminish the margins by seven times the height of such obstructions. Thus, an "L"-shaped field hav ing runways ioo f t. wide and margins of 15o ft. on both sides is sufficiently large if there are no surrounding obstructions. Should there be obstructions 5o ft. high the margins between the obstructions and the edge of the landing strip must not he less than 35o feet. (3) The airport must be very near a good highway to the nearest city or town. (4) The airport must have an im proved type of wind direction indicator and be marked by day with a landing circle ioo ft. in diameter having a band 4 ft. wide. The name of the city and field must be placed on the roof of at least one outstanding airport building, or near the marker circle or on other suitable area, in such manner as to be legible from an altitude of at least 2,000 feet. Six feet is the minimum height of the lettering. (5) The airport must be able to supply aircraft with fuel, oil and water, and the airmen with depend able communication and transportation facilities to the nearest city or town.

Geographical

Location.—MetropolitanAirports.—The aero drome should be as accessible as possible to the population which is to be served, although in the vast majority of cases of metro politan centres clear land is so scarce that the flying fields must be situated on the outskirts of the cities or in the suburbs.

The metropolitan fields, however, are the most efficient bases of aerial operations, naturally. Newark Metropolitan Airport in New Jersey is the eastern terminus of the transcontinental fly ing services, and as such is the busiest airport in the world, due, however, only to the fact that it serves New York City where considerably more than half of the nation's air traffic originates or terminates. There has been a great deal of agitation on the part of New Yorkers to have the traffic of Newark removed to Floyd Bennett field, New York's municipal airport located in the Borough of Brooklyn. New Yorkers have resented the distinc tion of the world's busiest airport going to New Jersey, although that State has countered with arguments that it was due only to Jersey enterprise and to some extent, Newark city financing, that the great eastern terminal was located within its borders.

Roosevelt Field on Long Island, one of the most historic aero dromes in the world, handles a great share of the flying in the New York area ; the Chicago Municipal Airport is a vast and busy flying centre ; other prominent fields include Grand Central Air Terminal at Glendale, serving Los Angeles and vicinity ; Union Air Terminal at Burbank, also serving the Los Angeles area, and the municipal airport at Kansas City. Lindbergh Field at San Diego is one of the most ideally located airports in the country, being a comparative few minutes from the business centre, but the other aerodromes mentioned, except at Kansas City, are all approximately ten miles or more from the hearts of the cities which they serve and the motor routes to them lead through heavy traffic. Time spent in getting from the field to the city, however, is negligible compared to the hours saved by aero plane as against ground transportation over any moderately long distance.

The big cities of the United States have long considered means whereby this problem of airport distance from town could be eliminated. Some architects have suggested construction of land ing sites atop steamship piers in the Hudson river; some aerial operators have suggested use of autogyros from the flying field to the flat roof of some building in the business centre; others have proposed seaplane "taxi" service. The proposals are many and varied, although none of them has come to much due chiefly to the advance in speed of American commercial aircraft, this ad vance permitting the expenditure of motor transit time on the ground between airport and city which otherwise would have evoked far more complaint than is now heard.

Size.

The weight of commercial aeroplanes necessitates gen erously long runways and wide safety zones through which to glide when approaching and to gain altitude when departing. The elevation above sea-level is important in determining the size of an airport as the length of runways required for taking off and landing increases with altitude. Thus an aeroplane re quiring 1,50oft. for a normal take-off at sea-level would re quire about 2,3ooft. at Denver, Colo., which is 5,28oft. above sea-level. An airport may be practically any shape which pro vides an unobstructed take-off and landing area of 2,5ooft. which is considered adequate for the largest aeroplanes. It should be planned so that it may be changed in the future.

The U.S. Department of Commerce Ratings on Size of Fields.—In order to receive a rating on size from the U.S. De partment of Commerce an airport must meet with certain basic conditions.

"A" Rating.—The field receiving an "A" rating must have landing areas in all directions with clear approaches, the field to be in good condition for landing at all times; or it must have approved-type landing strips permitting landing in at least two directions, the landing strips not to cross or converge at less than 6o° angles, with appropriate margins and clear approaches. The margin between any obstacle and the landing strip must be a distance at least seven times that of the obstacle's height.

The airport may be of irregular shape, but must contain enough area to permit landing space to fulfill requirements. A square field offers the most natural solution.

"B" Rating. —A square landing area 2,5ooft. on a side, laid out in landing strips permitting at least four-way landing and having clear approaches. The landing strips must be at least looft. wide and clear at the sides and ends. Margins between obstructions and landing strips must extend a distance of at least seven times the height of the obstacle. Landing strips shall not converge or cross at less than 45° angles, preferably intersecting at 90° angles in the case of four-way landing.

"C" Rating.—The field must have 1,50oft. of landing area in all directions with clear approaches and in good condition for landing at all times, or a square landing area 2,000ft. on a side, laid out in landing strips permitting at least four-way landing and having clear approaches. Landing strip, margin, obstacle and angle regu lations are as above.

"D" Rating.—The field must have 1,200ft. of landing area in all directions with clear approaches and in good condition for landing at all times; or, a square landing area of 1,50oft. on a side laid out in landing strips permitting at least four-way land ing and having clear approaches. The other regulations are as above.

"E" Rating.—The field must have a square landing area of 1,20oft. laid out in landing strips permitting at least four-way landing and having clear approaches. The other regulations are as above.

"F" Rating.—Fields not having the minimum dimensions of an "E" rating for size, but from which flying operations are nevertheless taking place, receive the rating of "F" if request for rating is made.

"X" Rating.—All fields not considered safe for the operation of aircraft, but which are used, or have been used for such operations, and on which rating is requested are rated "X." U.S. Department of Commerce.—Under the Air Commerce Act, the President entrusts the secretary of commerce with the bureau of air commerce of the department of commerce. In addi tion to its other duties the air commerce bureau co-operates with State and local authorities in establishing airports in all large cities. This act provides that airports shall not be owned or operated by the Federal Government, and that no exclusive rights shall be granted for the use of civil airways, airports or other navigation aids owned by the United States. The Department of Commerce may rate airports as navigation aids.

The programme of the Department of Commerce provides for lighting over more than 22,000 miles of airways. The lights are placed about 3om. apart between airports on intermediate land ing fields. The fields are leased by the Government and are not to be used for any purpose inconsistent with the landing and tak ing off of aeroplanes. A standard beacon is placed at every such intermediate field. On July I, there were landing fields in the United States, of which 693 were partially or fully lighted.

Cost and Revenue.

Data secured from 68 landing fields of various sizes located along contract air mail routes show an in vestment by cities of over $17,000,000.

The following analysis of the cost of the Buffalo airport when first built is typical of the expenditures in airport construction: Land (518 ac.) $411,000.00; building (3 hangars, 1 garage, administration building), $95,778.08; runways (2 cinder runways 3,000ft. long and iooft. wide), $48,528.56; grading and process ing, $47,875.32; new roads, drainage, $33,549.00; paving, $27,453.17; underground piping and electrical equip ment, $17,567.20; rolling stock and parts (I service truck, 1 five ton carryall, 1 light delivery truck, 1 coupe, 1 grader, 1 trac tor), $14,123.81; office equipment and supplies, $2,563.05; in surance $6,039.05 ; store-room supplies, telephone and light during construction, $671.23 ; machinery and tools, $9,580. 58; miscellaneous labour and supplies, $2,568.72. Income may be derived from rent from hangars, rent from postal, express and passenger accommodations, rent from restaurants, various conces sions, landing charges, night lighting charges, sale of gasolene and oil, etc.

Buildings and Equipment.

The Department of Commerce recommends that all buildings be situated at a point not nearer the landing area than seven times the height of the tallest building. To receive the rating "A" an airport must have one or more hangars at least Soft. by iooft. with a clearance of 18 feet. Where the ground is soft or muddy these should be connected with the runways by specially prepared roadways of cinders, con crete or other suitable material.

Drainage and Soil.

Artificial drainage may be supplied by blind ditches filled with coarse gravel topped with cinders, and tamped down flush with the surface of the field. If the precipita tion is heavy it is often necessary to lay tile pipe, with open joints, in the bottom of the ditches.

Landing fields surfaced with sand or cinders are seldom satis factory in dry weather as stones, sand or dust may be caught up by the air driven astern by the airplane propeller and prove annoying to passengers, damage wing surfaces and cause motor trouble. If the existing surface of the airport is not durable enough for continuous use it may be made so by sowing tough, deep-rooted grass which will not readily develop ruts, mud holes and tail skid scars.

Lighting.

The lighting facilities believed essential for the safe night operation of an airport are: (I) A rotating beacon of several million candlepower, tilted slightly upward and mounted on a tower in order to clear ob structions so that it may be visible in all directions.

(2) White boundary lights showing the shape and size of the airport.

(3) Green approach lights to show the most favourable ave nues of approach.

(4) Lights illuminating the wind cone, which indicates the pre vailing direction of the wind, against which the aviator has to land.

(5) Red obstruction lights to mark all buildings, pole lines, radio towers, and other dangerous obstructions within gliding or take-off distance of the landing field.

(6) Flood lights to give pilots the proper perspective and to indicate to them that portion of the field which should be used for landing.

(7) Ceiling lights which are used to enable the airport officials to determine the height of the clouds above the ground. This in formation is obtained by projecting a beam of light toward the clouds at an angle of 15°, and then measuring the distance from the light source to the point directly beneath the spot it makes upon the clouds, which gives the height of the clouds above the ground ; that is, the height of the ceiling. Information of this sort is transmitted to other airports so that aviators may be advised of the visibility at various points.

Identification Markings.

The centre of the landing field at each airport should be marked with a circular band 4f t. wide and Iooft. in diameter. This marker may be constructed by re moving the earth, where the letters are to be placed, to a depth of 6in., and filling in with smooth stones to the field level; white washing the stones makes the marker visible from a height of sev eral thousand feet. The roofs of factories and other buildings near the airport should be so marked as to aid pilots in finding the landing field with as little search as possible. Where the entire field is not available for landing, the runways should be in dicated by arms projecting from the circle described above.

Roofs of hangars or other structures at the airport should be marked with the name of the field. Arrows indicating the name and direction of other airports and cities, and also an arrow with a letter "N" superimposed pointing to true north should be dis played on the airport buildings. (J. C. McG. ; X.) General information on the construction and equipment of airports has been prepared by the Department of Commerce under various book and booklet titles.