established by a localizer beam, bisecting the runway and extending for several miles to bring the aircraft to the proper runway heading to the airport. The most precise form of instrument approach is the ILS type; the full Instrument Landing System approach consists of (1) a localizer beam, (2) a glide slope, also detected by electronic equipment in the aircraft, (3) marker beacons, (4) approach lights, and (5) runway lights.

Marker beacons, identified by equipment in the aircraft, tell the pilot the distance he is from the airport; the outer marker (OM) is usually 5.5 miles from the end of the runway (located on its center line extension). In many installations there is also a low frequency non directional beacon co-located with the outer marker to facilitate capture of the center line extension and localizer beam.

The middle marker (MM) is located about 1⁄2 mile out. (In early ILS systems there was also a boundary marker, on the end of the runway, but this type installation has been discontinued.)

ILS approach lights consist of a high intensity lighting system including the "ball of fire" strobe light installation which facilitates the pilot's transition from pure instrument flying to the visual phase of the landing.

Some airports have more than one approach system. At many airports the pilot will know that there are ADF approaches, localizer approaches, back-course localizer approaches, VOR approaches, and full ILS approaches. When the pilot is approaching the airport of destinatiton on an Instrument Flight Plan, he is informed by the ARTCC of the type of approach being used and that he may expect. This enables him to extract the correct approach plate from his flight kit and place it on a holder for study during the approach and landing. Sometime during the approach the pilot is told to contact the tower for a final landing clearance; after having touched down on the runway he contacts Ground Control for taxi clearance to his ramp.

What About Radar? The widely expressed reliance of laymen upon radar to solve all the problems of air traffic control seems to look upon it as an electronic panacea. Unfortunately this is not the case. Radar is only one part of the ATC system. It is a wonderful tool which makes expenditious handling of traffic easier, but the ATC system is designed so that the entire system cannot fail if one of its parts ceases to function. Radar is not a panacea by any means.

In elementary terms, there are two categories of radar operations: First, is the use of primary radar, in which the radar transmits a radio signal which is reflected from an object almost instantaneously, the "echo" recaptured and measured usually as a blip on a cathode ray tube. There is one advantage of primary radar: it requires no special equipment in the aircraft to reinforce the signal. However, it has some system peculiarities and serious limitations. Frequently aircraft blips will disappear altogether from a radar screen because of some electronic anomaly. The technicians talk about scalloping, ghosting, and interference. For a long time radar operators observed returns from ground targets such as nearby buildings. TV antennas, or trees ("ground clutter," in radar lingo). This was removed from the scope by instituting a circuit which will show only moving targets, called moving target indicator (MTI).

In earlier radar, precipitation areas, thunderstorm cells, and snow showers would create an echo and block out aircraft returns. This was cured by the institution of a system known as circular polarization (CP), which effectively cut out all but the most intense areas, such as the cores of thunderstorms, but showed aircraft targets clearly. The problem with CP is that pilots frequently find themselves steered by controllers right into areas of extreme turbulence simply because the controllers' radar scopes screen out violent meteorological phenomena.

In the last few years, FAA has entered into a great program of using "secondary radar" in aircraft. This equipment, which developed from the military use of similar equipment called IFF (identify, friend or foe), is known as a radar transponder. It reinforces the radar pulse echo and enhances the blip on the radar scope, and by isolating and detecting one of a number of selected codes the ATC can positively identify the aircraft with which he is working. In case of a loss of identity the aircraft can be instantly re-identified by a special identification flare are which shows up on the radar screen when the pilot is directed to "squawk ident." 17

17 The origin of this term is military. Transponder type equipment used for identifying flying aircraft was given the code word "parrot" and pilots were told to "have your parrot squawk ident."

Nearly 4,000 transponders are in general aviation aircraft today, although many radar facilities on the ground still do not have interrogation equipment which makes them effective. But transponders are not infallible. They, too, have system peculiarities: side-lobe interrogation, SSR shadowing (and resultant loss of blip), reflection problems, and garbling. FAA is now installing parametric amplifiers and side lobe suppression (SLS) modifications, but the false target problems and others caused by mixing electronic pulses from different aircraft are yet to be solved.

As the transponder comes into greater usage, new problems are developing in this technical field. Frequently upon arriving at terminal areas, pilots are directed to "squawk standby," which means "turn off the transponder." Thus we are right back to operating on raw radar primary returns. The busier the hub airport, the greater is the likelihood of being told to turn off the transponder,

II. ADEQUACIES AND INADEQUACIES OF TODAY'S SYSTEM

Obviously today's system has demonstrated its overall adequacies in practical use, with few exceptions. The 10 busiest airports served by the carriers are suffering greatly because the carriers are transporting more passengers through them than anyone ever anticipated. The problem is complicated by the fact that the air carriers, in order to meet the demand of the traveling public, schedule their flights competitively to meet this demand. The problem of peaking is not unique to aircraft; it faces every mode of public transportation: trains, intercity busses local busses, and taxicabs.

However, except for these 10 locations neither the air traffic problem nor the passenger handling problem in the terminals is really acute, yet. However, there is a real concern by all users of the airspace that the situation will become acute in the very near future.

In the hypothetical flight plan from Washington to New York above, it can be seen that the ATC "system" works perfectly for a relatively few aircraft. But the ATC system, like a chain, is only as strong as its weakest link. In aviation the weak link is the saturation level of the system, including the airport acceptance rate and approach system saturation under actual minimum instrument approach conditions. All reasonable air carrier scheduling must be based on this criterion. It is imperative that the difference between operating under these restricted circumstances and operating under visual conditions be always separated when considering the problem.

All federal airways must begin and end at an airport. Some airports absorb a load that no one could have imagined 25 years ago.

The New York area, for instance, with three airports served by U.S. and foreign flag carriers, is literally a target at which airplanes are fired from all parts of the world 24 hours a day, 365 days a year. Air travelers stream in from places like Miami, Atlanta, Dallas, Las Vegas, Los Angeles, San Francisco, Chicago, Ottawa, London, Paris, Rome, Tokyo, and many other great urban centers. Every airplane arriving, from any direction, must be handled by New York ARTCC, which under actual instrument flight conditions guarantees them airspace separation. The burden carried by the human being who man the New York Center is incredible. It is easy to understand why the New York Center every so often must report that the system is saturated and that it therefore cannot accept any more traffic. Under actual instrument conditions there is, all too frequently, simply no airspace left.

Airplanes approaching the New York area (and New York is only an example-every one of these cities mentioned can have the same problem) must then be told to "hold" at a certain designated holding point because the air traffic control system is incapable of affording them protection in the final approach and landing phase of the flight. By weather restrictions, the actual airport acceptance rate can be reduced from 120 movements (the acceptance rate under good weather conditions) to 40 or 50. The situation is similar to the familiar one on an expressway when cars moving at 50 mph find themselves in an immense traffic jam because someone at the head of the line is driving 30 mph. The ATC system, both en-route and for controlling approaches, is handled on an individual controller-to-pilot "hand holding" basis. Each pilot is personally directed to fly at a certain altitude and along a course that will insure him separation. Every aircraft movement must be manually directed and controlled by human beings on the ground. This individual handling system will not be adequate to handle the instrument flight traffic volume in a few years. The answer is computerized automation, a subject that seems too much like Jules Verne

to be taken seriously. FAA has such a program working experimentally in simulation exercises now. By 1980 it will be a part of the system.

The People Problem.-The inadequacy of the solution of the problem of people handling on the ground is also being recognized as critical in many cities. Airline terminal buildings are constantly being enlarged; ticketing and baggage facilities are expanded to meet the demand. Yet standing in line, departure and arrival delays, and lost baggage are all sources of irritation to say the least for the airline traveler. Arrangements which were satisfactory for the passenger volume of small air carrier airplanes are no longer adequate for today's needs. Certainly they cannot be considered for tomorrow's.

III. THE NEEDS OF TOMORROW

The airport runway and ATC problem must be met if the number of air carrier and non-air carrier aircraft involved in our national air transportation system is to continue growing. But, there can be no system plan without cooperation of all concerned. Runway requirements at many airports are dictated by the type of aircraft acquired by the carriers-a unilateral management decision, frequently made without reference to the fiscal capabilities of the communities served to meet such needs. Only 25 airports will be able to handle the Jumbo Jets and the SST. Also, at the present time only 157 airports can handle pure jet equipment of the airlines.

The Needs of General Aviation.-Relatively few general aviation aircraft require runways such as those needed by the air carriers. Many communities have expanded airport capacity by relieving the traffic pressure on jet runways used by large aircraft by building 4,000 to 5,000 ft. parallel strips, which will easily accommodate by far the greatest percentage of general aviation aircraft. These runways do not require either the length or the heavy structure as those of the large jets. At Washington National the tower controllers can handle departing or arriving general aviation light aircraft traffic under visual flight conditions by directing them to land on 1,200 or 1,500 ft. of the intersecting runways which can be done without impeding the flow of heavy aircraft traffic on the long runways. Under instrument flight conditions National Airport's acceptance rate is severely curtailed and there are delays.

With the development of new approach aids and precision navigation systems it would be possible to use parallel runways on many existing airports simultaneously for air carrier and general aviation instrument approaches. Proper long range planning of the national airport system can solve the problem at almost every location.

People fly to an airport because they want to go to the community it serves. The reason for going is not important. The air carriers do a thriving business in carrying passengers to resort areas for fun and recreation as well as to other areas on business. The air carriers are businesses operating for profit. What is needed, therefore, is a planned program for creating a system of general aviation airports which will give access to air carrier served communities and will relieve the traffic pressure on the large airports. What is needed is a system of equally accessible airports for general aviation.

The ideal reliever airport situation can be found in the Twin Cities of Minneapolis-St. Paul. The reliever airport program planned and executed more than 20 years ago developed a ring of general aviation airports and has made it unnecessary for general aviation users to land at the airport used by air carriers. No regulations bar them; indeed some general aviation aircraft do use the facilities without any problems whatsoever.

The political problems involved with instituting such a program are tremendous. It is acknowledged that few communities want airports usually upon a highly emotional basis, but this situation must be faced directly.

The requirements of air taxi and commuter airlines which are also air carrier operations, since they also carry passengers for hire (frequently for the purpose of interline transfers with the certificated airlines) must be considered in this long range plan.

FEDERAL AID TO AIRPORTS PROGRAM

The Federal Aid to Airports Program (FAAP) has been rendered inadequate for the very purpose for which it was formed. Historically FAAP has been

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18 Although the legislative intent of Congress in passing the Federal Airport Act was to encourage general aviation through a nationwide system of good general aviation airports, the result 20 years later is that the program is approaching the billion-dollar level for 2,300 airports instead of the 6,000 originally intended; also, 83% of the total funds have been spent on airports used by the air carriers.

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under-funded by Congressional appropriations and Administration policy. What funds have been available have gone largely to improve airports served by the air carriers and to enlarge runways and ramps directly as a result of the carriers' unilateral decision to institute service with heavier and more capacious equipment. General aviation has been given little consideration.

The entire FAAP has received an annual appropriation of $75,000,000—the cost of 50 miles of high speed highway. This fact certainly illustrates the inadequacies of the appropriation under the program supposedly created to establish airport facilities for the benefit of small communities.

THE PASSENGER HANDLING PROBLEM

In order to handle the volume of individual people who will be transported by the certificated carriers, a system of mass transportation of parallel capacity between the community and the airport is needed. A plan must be developed which will induce air travelers not to drive their own cars to airports. Such a system must be economical to these passengers and at the same time offer them rapid transportation. The answer, we believe, is to develop a high density modular rapid transit system using equipment that is compatible with city streets, like a bus, yet which can be integrated into a monorail or rail track system so that several units can be joined together to carry several hundred people to the airport at once. By such a system airline passengers could be collected at various points in the community, then transferred as a group to the airport, and delivered either to a particular aircraft or to a terminal building facility.

CONCLUSIONS

1. The national air transportation system depends upon a balanced interrelationship of:

(a) Aircraft.

(b) Airways system.

(c) Air traffic control system.

(d) Airport system, including general aviation reliever airports.

(e) Airport/downtown mass transportation system.

2. The critical aspect of airport air traffic saturation is the airport acceptance rate under adverse (IFR) weather conditions, defined as the minimum instrument approach conditions.

3. The most critical congestion problem of the ATC system is based on the high traffic volume of approximately 10 urban centers, or hub airports.

4. The problem of passenger handling must be considered separately from the problem of aircraft handling by the ATC system.

5. The terminal problems on the ground are:

(a) Adequate ramp space for air carrier aircraft at the terminal.

(b) Passenger handling facilities within the building itself.

(c) Public transportation of passengers between the airport and the community.

(d) Public parking facilities for those using the airport.

6. There has never been any formulation of an integrated national air transportation system plan which would consider the needs and requirements of all aircraft at all types of communities, or of the passenger support facilities required for such an overall system.

RECOMMENDATIONS

Believing that free enterprise businessmen who have a real interest in the problems of airports and aviation safety can act together to solve them expeditiously and practically, we recommend that there be created a commission patterned along the lines of the Radio Technical Commission for Aeronautics, setting up a program whereby representatives of FAA, the air carrier industry, the general aviation industry, and the state aviation commissions unite to design a national air transportation system, giving full attention to the needs of the future growth of aviation.

We recommend further that this body make budgetary recommendations to the Congress and to the administrations of the several states involved so that such a national transportation plan may be fully funded and implemented. Thank you again for this opportunity to testify.

Mr. SMITH. 1 think, Mr. Chairman, the biggest problem we have, despite all the curve balls thrown here, is to define the problem of crowded air and define the safety problem and have some idea of what we are really talking about. We have in this country some 8,000 airports registered with the FAA. Five hundred and twenty-six of those are served by the certificated carriers. For some reason or other, it has become popular for those to be called commercial airports or airline airports. They are not. They are public airports. They are public facilities paid for by public funds.

The airline fleet consists of 2,000 airplanes; they are not all flying at the same time. We have two types or, I should say, three types of aircraft flying under certification of CAB. We have the domestic trunks, there are 11 of those. They fly 1,117 airplanes according to the last statistics I have available from the CAB.

We also have the 13 local service carriers which fly 395 airplanes. Incidentally, 97 of those are DC-3's, which is still the largest number of a single airplane type used in local service carriage. We also have 13 supplemental airlines which run about 200 airplanes, depending on what their financial status is at the moment.

The problem of the crowded air, which is what the press is pleased to call it, really exists in a very few locations.

There are 10 places in the country that really qualify for what we would call major traffic hubs and every one of these 10 places is jammed with airline traffic because these are central locations where people want to go and they want to go not only by public carriage, by the certificated carriers, but by their own airplanes.

Mr. FRIEDEL. Would you care to name the 10 airports you are speaking of?

Mr. SMITH. I put my stuff away because I thought I was going home but I will be very glad to give it to the stenographer. (Chicago, O'Hare, John F. Kennedy, Los Angeles, Miami, Denver, Phoenix, St. Louis, San Francisco, Atlanta, Cleveland.)

The fact is that you must make a complete differentiation between actual visual flight conditions and actual instrument flight conditions. The criteria, the tight part of our whole airway system comes when the actual weather at instrument conditions requires instrument approaches at a hub airport. When this happens each airplane must be separately handled and frequently there is a 5-minute interval between handling the airplanes.

Here at Washington National Airport under instrument flight conditions it is said the airport has a capability of handling 60 flights an hour. There has been an arbitrary figure put on those: 40 for the scheduled air carriers and 20 for general aviation which includes 16 air taxi operations an hour, and these air taxi operators, I submit, are also commercial carriers, although they are not certificated by CAB.

Under visual flight conditions the fact that certificated airlines are filing instrument flight plans does not mean a thing. The airport movement acceptance rate at National Airport using light aircraft under good visibility conditions goes up to 120, sometimes 130 per hour.

I have a light airplane. I fly a light twin. I am completely equipped with everything that Mr. Tipton just talked about a little while ago, including a 4096 code transponder. I can come into Washington Na