Your illustration this morning of the vacuum cleaner is an illustration of the type of interference which we believe leads to this term of "spectrum pollution" used by the Commission in its supporting statement of S. 1015.

This type of interference generally can be eliminated by very simple techniques which are employed by some manufacturers and not others. For example, in the case of your vacuum cleaner, proper design of the motor and the use of a very small capacitor about the size of the eraser of a lead pencil would eliminate most of that interference.

We believe that the Commission should have authority to cause manufacturers to take these precautions which are nothing more than good engineering practice.

At the same time, we are concerned about proposals to erect highvoltage transmission lines in certain parts of the United States which, because of their particular design characteristics and the high voltage, will cause, we believe, interference or may cause interference to all radio reception within some thousands of feet of these lines.

We understand the need for high-voltage or high-efficiency transmission lines, but believe that they should be limited to the rural areas where the population is not very dense rather than to built-up areas. We have occasions of this occurring in some major metropolitan areas in the United States.

The third subject I touched upon in my statement was the question of interference to television receivers, for example. Much of the interference to television receivers is caused by poor design of the receivers themselves. They are susceptible to signals received which are transmitted on frequencies other than the desired frequency to which the receiver is tuned.

This again can be taken care of by a very simple application of good engineering principles and parts which cost only a very few cents in each case, and we believe that S. 1015 should be broad enough, if enacted, to enable the Commission to insure that these

Senator PASTORE. In other words, this legislation is not motivated by any capriciousness on the part of anyone. It is merely a question of live and let live? All these things can be adjusted in such a way that not only we can get good reception but at the same time we can carry out the function of this apparatus without injury to anyone with a little bit of cooperation and coordination?

Mr. BOOTH. Yes sir.

Senator PASTORE. And the compulsion of the law is because of marginal cases?

Mr. HENRY. That is our interpretation of it; yes sir.

Senator PASTORE. Heretofore, there has been fine cooperation with the industry and the FCC? Is that correct?

Mr. HENRY. We believe so.

Senator PASTORE. All right.

Is there anyone else in this room that wants to speak on any of the bills that have been presented today?

Is Mr. Thomas here?

Mr. THOMAS. Mr. Chairman, I am David Thomas of the Federal Aviation Agency.

Senator PASTORE. Would you come forward, sir?

Now, this is on what bill? S. 1015 as well?

STATEMENT OF DAVID D. THOMAS, ASSOCIATE ADMINISTRATOR FOR PROGRAMS, FEDERAL AVIATION AGENCY

Mr. THOMAS. Yes sir.

If I may, Mr. Chairman, I would like to file for the record our comments on both S. 903 and S. 1015.

If I may also, I would like to respond a little further to two questions you asked of Mr. Henry.

Senator PASTORE. All right. No. 1, these statements will be inserted in the record at their proper place on each of the two bills.

(The statement of Mr. Thomas follows:)

STATEMENT OF DAVID D. THOMAS, FEDERAL AVIATION AGENCY, ASSOCIATE ADMINISTRATOR FOR PROGRAMS

Mr. Chairman and members of the subcommittee, I am David D. Thomas, Associate Administrator for Programs of the Federal Aviation Agency. On behalf of the Administrator and myself I want to thank you for inviting us to discuss with you two important bills you are considering today, S. 903 and S. 1015.

S. 903

In 1955, the Air Coordinating Committee established the Joint Industry Government Tall Structures Committee (JIGTSC) to investigate the problems raised in the joint use of airspace by the aviation and broadcasting industries, and to recommend appropriate action establishing the position of the Federal Government in this matter. That Committee consisted of representatives of Government agencies having an interest in problems of airspace utilization, and representatives of the aviation and broadcast industries.

One of the JIGTSC's recommendations was that the FCC require the removal or appropriate lighting and marking of unused or abandoned towers if it had such authority, and, if such authority did not exist, that the FCC seek appropriate legislation to obtain this objective. We agree with the conclusion of that Committee on this issue and urge that S. 903 be enacted in order to carry out its recommendation.

Antenna towers constitute a particular danger to pilots, both because of their height and their peculiar structure. There has been a rapid growth in the height of such structures over the past 10 years, the number of the towers over 1,000 feet increasing from 19 in 1954 to 147 today. In addition, there are 57 more towers pending approval which are designed to reach above 1,000 feet.

The tallest tower in existence stands 2,063 feet above the ground. The FCC has issued a construction permit for one more tower above 2,000 feet and there are applications pending for two more of these towers.

The staggering proportions of one of these structures is demonstrated by this illustration (FAA fig. 1). It shows a 2,000-foot tower placed next to the Empire State Building, the Eiffel Tower, and the Washington Monument. The guy wires of the antenna towers form an umbrella for all three structures.

These tall towers are not only potentially dangerous because of their height, but because of their peculiar shape and structure. An antenna structure is extremely difficult to see from the air because the tower is extremely narrow, and its latticed construction makes it virtually transparent.

The marking and lighting of antenna structures is particularly essential to the safety of pilots operating VFR, or in accordance with the visual flight rules. This means navigating through the air by reference to visible objects. Most of the 96,000 privately owned aircraft are flown VFR, and these aircraft are flown generally at the lower altitudes.

The VFR pilot is not always certain of his exact location in relation to a given obstruction unless he has the obstruction in sight. Major obstructions to flight are marked on aeronautical charts and, prior to take off, pilots familiarize themselves with such obstructions along their proposed route of light. But the pilot in navigating between two points, like the motorist, does not know precisely where he is at all times in the journey between the two points, so he may not know precisely when he will reach the site of a known tower. Therefore, it is most important that the tower be made as conspicuous as practicable so that the pilot will be able to see it in time to make the necessary maneuvers to avoid it.

Perhaps the most dangerous situation for the VFR pilot is when he is operating in an area where antenna structures are located, and the ceiling, and/or visibility conditions are near minimums. Under these conditions, the pilot often must operate at low altitudes, and his attention is directed mainly to the surface for the purpose of visual guidance. Unfortunately, however, because of these same weather conditions, the silhouette of an antenna is harder to detect, and there is greater necessity than ever that it be properly marked and lighted for his protection.

These difficulties in detecting antennas are present and real even under existing marking and lighting requirements and we are working with the FCC to improve the marking and lighting of towers. Detection would be infinitely more difficult, in many cases impossible, if an antenna were not lighted or marked at all.

At present, there are over 7,000 authorized AM, FM, and TV broadcasting stations, and about 900 applications for construction permits are now pending. As long as a broadcasting tower is subject to FCC jurisdiction, the broadcaster is required to provide marking and lighting protection prescribed in regulations issued by FCC. When a broadcasting tower is abandoned, however—and potentially any one of the thousands of towers utilized by these stations could be abandoned the protection of this marking and lighting is no longer assured, for the Commission's authority to regulate in that area is terminated. S. 903 would extend the Commission's authority to fill this regulatory gap, and thus afford the public continued protection against unmarked and unlighted towers. If the tower no longer serves a useful broadcast purpose and it is found that its existence may create a menace to air navigation, the owner of the tower should be required to dismantle and remove it. S. 903 will provide the authority necessary to assure such a result, and we strongly recommend its enactment.

I would like to describe how radio frequency interference can affect aircraft navigation and communications, and the resultant unfavorable impact on air safety.

There are different types of electronic devices located all over the United States emitting signals which, when received in an aircraft, provide vital information to the pilot. These are known as radio aids to air navigation or more commonly as navaids. The pilot relies on these aids to navigate his aircraft safely from one point to another, and to land his aircraft when weather conditions are such that he could not land without the help of these signals.

VOR

An example of a navaid that is affected by interference is a device known as a VOR. This diagram (F.A.A. fig. 2) has depicted on it four VOR's. Each of them emits signals outward in all directions. The transmitted radio beams are detected by the airborne receiver, and direction from the station is indicated by degrees from or to the station. These degree lines are called radials. Radials project precise pathways through the sky. A pilot can find any radial by tuning his receiver to the published frequency of the VOR, determining the radial he is on, then navigate to, and then along, any preselected radial. In the continental United States alone there are 814 VOR facilities operated by FAA. Together they form a vast and intricate network of simulated highways vital to the safe navigation of aircraft.

It sometimes happens that radio-frequency interference near a VOR will require us to discontinue the use of the radials in the sector where the interference is located. This means that some of our aerial highways are rendered useless, including some intersections important in the efficient movement of air traffic. Another area of air navigation where radio-frequency interference becomes most critical is in the instrument-landing system, or ILS. The ILS is used for landing in adverse weather conditions. One of the components of the ILS is the localizer. The localizer emits a signal that is used by the pilot for centerline guidance to the runway. Radio-frequency interference can cause the localizer to be rendered useless altogether, or it can cause to be displayed to the pilot erroneous centerline-guidance information.

The FAA operates numerous other types of air-navigation facilities which are susceptible to the radio-frequency interference. They include short-range and long-range radar, distance measuring equipment, TAGAN bearing and distance equipment, and direction-finding equipment.

Radio-frequency interference can also create problems in communication between air traffic controllers and pilots. There is a considerable amount of air/ ground voice communication in providing separation between aircraft during departure, en route to destination, and landing. When frequencies used in these voice communications are cluttered or made unusable by interference, difficulties are created that add to the burden of the controller and the pilot. When interference on an air traffic control frequency becomes so great as to make the fre

quency unusable, the controller must switch to another frequency. This involves calling each aircraft under his control to inform the aircraft of his new frequency. This process diverts the controller's attention from his main task of controlling the aircraft.

Radio-frequency interference can not only cause delay and inconvenience but can create situations which could result in disaster. Where voice communications between controller and aircraft pilot are distorted or blanked out, vital communications at a critical stage in the flight may be lost, perhaps even a warning of impending collision with another aircraft. Interference may prevent the pilot from identifying the station he may be attempting to navigate by. Or interference, from a garage-door opener to use an example we have had some recent experience with, could cause a pilot to deviate from his intended course and thus fly into an area where he should not be. Any of these situations could cause or contribute to an aircraft accident.

Let me show you this chart (F.A.A. fig. 3) how one segment of the aviation radio spectrum is affected by an unregulated radio device, such as a garage-door opener.

Each authorized user in this band needs only a small piece of the spectrum to operate on, as illustrated by the "spikes" on the chart. The garage-door opener radiates energy over a large portion of the band, thus polluting the spectrum. At present, where radio-frequency interference affects navaid performance or voice communications, the source of the interference must be located through aerial inspection and use of radio vans on the ground. When the source is located, action must be taken against operator of the interfering device to close the device down or have it modified to eliminate the interference. Recently, in the Los Alamitos area of California, a serious amount of interference was noted on 243 magacycles, the frequency used for emergency communications, and on 282 megacycles, the homer frequency for the lost Alamitos Naval Air Station. A task force consisting of Navy, FAA, and FCC components undertook to locate the offending devices and take action to eliminate their effects. This team, using ground vans, automobiles, and a helicopter, located 58 garage-door openers emitting interfering signals. Those 58 devices were only a small percentage of the total offenders, and it took a week to locate that number. The cost of this operation to the Government was about $100 per garage-door opener closed down. This example illustrates the cumbersome, costly, and only partially effective, measures that must be utilized to get at and eliminate interfering devices under current law. If S. 1015. were enacted, however, a much more effective and much less expensive means of eliminating interference would be available; namely regulation of the manufacture of such devices. We therefore strongly urge enactment of this bill.