Thursday, August 13, 2015

ADF navigation history (reprint)

How it Began

Jenny Airmail biplaneFlashback to May 15, 1918, to Washington, DC. It’s early Wednesday morning, a blustery day. President and Mrs. Woodrow Wilson are in the grandstand. So is Assistant Navy Secretary Franklin D. Roosevelt. The Postmaster and second assistant Postmaster wouldn’t have missed this day for anything. Members of Congress arose early to be there, too, pondering whether to allocate additional funds for this new service.
Lt. Boyle has just mounted his Curtiss Jenny biplane, four sacks of mail weighing 150 lbs secured in the front cockpit. All eyes are on the frail World-War-One aircraft in Washington’s Polo Grounds, anticipating the great event.
Airmail service will be inaugurated on this day. And the Army and Post Office Dept. have been jointly charged to provide that service.
In only moments flights will simultaneously disembark from Washington and New York’s Belmont Park Race Track. Each will stop at Philadelphia to deliver and pick up mail, refuel, change pilots, and then continue on to the other destination. A large crowd mills about at Philadelphia’s Bustleton field, too, excited to be part of this highly-publicized history-in-the-making.
In Washington, mechanics hover near Boyle's aircraft, ready on the signal to "prop" the plane, to bring the engine to life. Boyle gives the thumbs-up, shouts "Clear," then "Contact!" The mechanics take their cue with a swift pull on the prop ... nothing. They try again ... still no roar of the engine. Repeatedly they try, without success. The honored guests in the grandstand become restless.
A holler comes from the side "Check the fuel!"
The mechanics do and, embarrassed, find the tanks dry. Quickly filling the tanks, they again prop the plane. The engine’s roar reaches the grandstand. A cloud of blue smoke envelops all standing nearby. Worried frowns by those from the Post Office Dept. turn into broad grins. Army personnel reappear from behind the grandstand. Everybody is friends again.
In but moments, the Jenny leaves the ground, struggling for altitude, anxious to clear the trees that rim the sports park. News reporters and photographers race back to their offices to begin work on the front-page coverage planned for the afternoon editions.
Less than twenty minutes into the air on his way to Philadelphia, Boyle gets lost, lands in a farmer’s field, and severely damages the plane's prop. The Army rushes a new prop to the site. But the airmail will not go through that day. It is returned to Washington.
NYT HeadlineThe press is generous with its praise of the newly-inaugurated service. It dismiss the crash in a single sentence—"With the exception of an accident to one of the airplanes between Washington and Philadelphia, it was a complete success." That Boyle took off in the wrong direction and crashed south of Washington apparently was considered un-newsworthy.
The south-bound aircraft had left Belmont Park as scheduled, and flew uneventfully to Philadelphia. Six minutes were consumed there transferring mail, refueling, and changing pilots and then the Jenny successfully continued its journey to Washington, to little publicity, other than a small headline.
Three months after the inauguration of service the Post Office was delegated full responsibility for Airmail service.

The Transcontinental Route

The Washington to New York route proved a commercial failure.
Once the novelty wore off of posting an airmail letter from Washington to New York or back business dropped drastically. The distance covered, 218 miles, was too short to permit any substantial time saving over existing surface transportation. Twenty-four cents was a hefty price to pay for a few hours saved in mail delivery time.
On average mail planes were carrying only seven pounds of special airmail per trip; the rest was selected first class. The Post Office lowered the postage to 16 cents. Still expensive, business only increased slightly.
The Post Office Dept realized that Air Mail's value lay in cross-country delivery where significant time could be saved. The New York to San Francisco route was chosen to test transcontinental Airmail service. By 1920 fifteen fields spaced approximately 200 miles apart over a 2680-mile route made up the airway.

Transcontinental Route 

The transcontinental airmail route ran from New York to San Francisco. Intermediate stops were: 2) Bellefonte, 3) Cleveland, 4) Bryan, 5) Chicago, 6) Iowa City, 7) Omaha, 8) North Platte, 9) Cheyenne, 10) Rawlins, 11) Rock Springs, 12) Salt Lake City, 13) Elko, and, 14) Reno.

Air Mail Service pilots were the unsung heroes of early aviation. In their frail biplanes, they battled wind, snow and sleet to pioneer round-the-clock airmail service along the world's longest air route, the U.S. transcontinental. In the process, thirty-four pilots lost their lives.
Since September 1920, the Post Office Dept. had flown the mail from New York to San Francisco, but during daytime only, transferring it to trains at night. As a result, elapsed time was 72 hours at best, or a mere 36-hour saving over the fastest all-rail trip.
Flying the mail was risky business. During the nine years the Post Office Department operated the Airmail Service, there were over 6,500 forced landings. On the average, airmail pilots had a life span of only about 900 flying hours.
The Post Office Dept. increased the pressure on its pilots by announcing that the air mail flights could be conducted on a schedule 93% of the time.
Flying in open-cockpit biplanes, exposed to the bitterly cold air and harsh weather conditions, the pilots often became so numbed and exhausted that they couldn't think clearly or make decisions quickly. Not publicized by the Post Office Dept. was the fact that in order to fight the cold and the constant pressure of deadlines, with on-time delivery expected under even the worst of flying conditions, many of the pilots carried bottles of liquor along when they flew.
Carrying the mail was not the only business of aviation. In 1914 the world's first regularly scheduled air-passenger service opened up along a 22-mile route from Tampa to St. Petersburg, Florida. The service could carry only one passenger at a time and cost $5 for the 23-minute flight. It was a financial failure and lasted only a short time.
These early days of aviation presented a unique set of problems and the inability of aircraft to navigate in rough weather and darkness topped the list. The government became involved in 1926.
Beacon at intermediate landing fieldThe first navigation-aid system consisted of flashing beacons. These high-intensity lights, located along popularly-flown airways, literally shone into the air like a connect-the-dot puzzle, winking and blinking a friendly invitation to come ahead.
The beacons, of course, did not flash, but rotated through a complete circle giving the impression of flashing.
In October 1931, D. C. Young of the Airways Lighting Sub-Committee recapped the progress of lighted airways at a lighting conference in Pittsburgh, Pa.
"Ten years ago, a scheduled night flight by airplane across the United States was only a dream. Now, such flights occur nightly, and on scheduled time. The converting of this hazardous journey into one of comparative safety ... is the achievement of constructing aerial highways for the airman.
If air travel were confined to daylight hours only, the speed and directness of route would give the airplane little or no advantage over fast trains operating on 24-hour schedules. The Post Office Dept. realized this in 1922 when it was transporting the mail by air. So it established facilities for the airmail pilot to follow at night and succeeded in showing a remarkable improvement in speed on the coast-to-coast route.
In the four years since 1926 when the government took over the airways 14,500 miles of lighted highways had been created for the airmen.
High-intensity beacons are established approximately 10 miles apart along these civil airways . The beacon consists of a 24-inch parabolic mirror and a 110-volt, 1000 watt lamp. The beacons, which rotate at 6 rpm, show a one-million candlepower flash every 10 seconds for 1/10th second duration.

Intermediate landing field, Omaha-Chicago route 

Pilots often stopped at McGirr Field, on the Omaha–Chicago route, when they had an "emergency," knowing that the food was excellent and that they would be well cared for.

Intermediate landing fields are provided every 30 miles along these routes, in the absence of suitable commercial or municipal fields, and each is equipped with beacon, boundary, approach, obstruction, and wind-cone lights.
airway beacon lightThe beam from the airways beacon is a high-intensity pencil of light of about 5-degree beam width visible 20 to 40 miles in clear weather. The beam is aimed 1.5° above the horizon. A small percentage of the beacon’s light is reflected upward to provide close-range visibility.
Two course lights are mounted on the tower just below each searchlight; one points forward along the airway and the other points backward. These 500-watt searchlights give a 15 degree horizontal beam width.
The course lights are fitted with either red or green lenses. Every third beacon has green course lights signifying that it is on an intermediate landing field. Thus the pilot knows at a long range the availability of landing fields. (This is the forerunner of today’s airport rotating beacons which alternately flash green and white.)
All other beacons had red course lights.
As the mechanism revolved and the clear flash of the beacon passed from the pilot’s vision, the red or green flash of the course light came into view. Course lights flashed coded dot-dash signals to indicate the beacon’s position on the airway. Code signals ran from 0 to 9; thus, if a pilot received a signal for the number 4, he knew he was flying over the fourth beacon of a particular 100-mile stretch of airway. But he could not determine his precise position merely by receiving a course-light signal if he did not know independently over which 100-mile stretch he was flying.
airmail posterLetters designated the airways, the first letters of their terminal cities. The order of the letters was established as south to north and west to east. Thus Omaha to Chicago was Airway O-C. LA-SF defined the Los Angeles to San Francisco airway, and so forth.
Regular maintenance of the airway beacons and intermediate fields was crucial. This duty was entrusted to Airway Caretakers. Daily they climbed the 51-ft. steel towers to check every beacon within their territory, cleaned dirty lenses, replaced burned-out bulbs, etc. Repair problems requiring more expertise or equipment and tools not locally available were referred to "mechanicians," who serviced a 175-mile route with a half-ton pickup truck.
Caretakers at intermediate fields were on duty from 6:00 pm to 6:00 am. If a pilot "dropped" in to one of these emergency fields, caretakers were expected to provide transportation to and from town, furnish them with meals, and assist in repairing their aircraft.
To "Plane Post" a letter cost 24 cents an ounce in 1918, which included special delivery.
With airways on the transcontinental route now lighted, airmail could be delivered in one-third the time of a train.


thank-youAlthough I did the keyboarding for this site it contains the fine contributions of many people.
With no prior experience in building a website I was overwhelmed at the generosity of those that I asked for permission to either reproduce their work, or for their technical help, or to use their designs, artwork and descriptions.
Many thanks to those listed below in alphabetical order, who so willingly shared their talent so that I could assemble these webpages:
Bob Austin, of Mission Viejo, California. A scenerio in the VOR Approaches section required an over-kill list of mountaineering equipment for Mr. Benjamin Counter. Counter intends to "scale" southwest New Hampshire's 3165 ft. Mt. Monadnock, the second-most climbed mountain in the world, behind only Mt. Fuji in Japan. Since Florida's highest "mountain" just reaches 345 ft. I had to look elsewhere for an expert. Bob Austin jumped right in, providing an awesome equipment list, which I had to shorten. Any omissions are my work, not his. Bob has the credentials to provide an accurate and complete list, too. In his climbing he's completed six big-walls including two El Capitan routes—The Nose and Triple Direct. Thanks, Bob. Just reading your equipment list I could imagine the wind fiercely blowing off the face of the mountain, daring any climber to move higher.
Wagner Beskow, for his Handy Sheet 3.0. Wagner, a Brazilian in New Zealand taking his Ph.D., assembled this one-page compendium of useful facts for the flight-simmer. "It takes a while for a beginner to find all that information and when he does it's all scattered and difficult to refer to. The idea was to produce something useful that could stay around without cluttering the 'cockpit' too much." Thanks, Wagner. I wish I could say my cockpit was uncluttered now.
Boeing Company, photo of 40-A mailplane. The 40-A, a fabric-covered mail plane, was Boeing's first commercial success. Built in 1927 (the year Charles Lindbergh crossed the Atlantic), it carried mailbags and—load permitting—two passengers.
Tom Christine, Electrical Engineer, Federal Aviation Administration. Tom was very helpful on specifics about present-day Non Directional Beacons, including their power levels, uses, their friendly coexistence with GPS, and frequency limits of the LF band. Thanks Tom.
Mario Corral, Sydney, Australia, who sent me the sketch of the homing pigeon. Mario patiently explained to me some similarities and differences between homing pigeons, racing pigeons, and carrier pigeons. Thanks Mario for keeping me on the right track.
Rick Covington, photos of the Piedmont DC-3 in the "On the Beam" section. Thanks Rick ... an excellent photo. You can find more of his photographic expertise at He photographed the Piedmont shown here in Durham, N.C.
Mike Genovese for the finest interior shot I've seen of any aircraft. "The shot was taken in Nassau in the early 90's... the plane was just sitting there unattended as we (crew of a major airline) walked by on the ramp... I could not resist the opportunity for the 'Kodak Moment!' ... " Great pic Mike and keep your camera handy as you jet to all those tough destinations. See for more of Mike's work.
Jesse Kempa for his virtual E6-B calculator program. This program does it all, and best of all, it's freeware. Input True Course, TAS, wind speed and direction and on the click of a button it returns the Wind Correction Angle and Ground Speed. It will calculate distances between points with known lat. and long. coordinates, and on and on. Thanks Jesse for a great
Brian Kostick, the gauge programmer of the very-useful digital Elevator Trim indicator. With it the pilot has repeatability in elevator trim settings. Thanks to Brian,, for an instrument that I rely on and for his quick willingness to let me use it in this panel.
Paul Lutus ... who wrote the freeware HTML editor "Arachnophilia" which I used in assembling these webpages. Arachnophilia is a full-featured, nearly perfect editor—and now v4.0 is even better with a 120,000 word spell-checker. Paul has an outstanding philosophy on life, too. Thanks, although we've never "met."
Alice Marks ... for the extraordinary sketch of McGirr field. That picture is the essence of the intermediate fields that Air Mail pilots aimed for when facing an emergency. Her artistry instantly backed me onto McGirr field—into the new era of Air Mail, with the wind sweeping across the plains, striking me in the face. But then, it should have because Alice Marks's father was McGirr field's caretaker and Alice grew up there. She has a wonderful first-person account of the activities at the field that beats anything you'll read in stuffy history books. Take five and go to her site and relive the experience. Thanks Alice, twice ... for sketching McGirr field to keep that kernel of history alive and for letting me share it with others.
Ned Preston, Agency Historian, Federal Aviation Administration. Ned provided the chronology on when VORs were introduced, a whole wealth of information on the four-course radio range and on the light-beacon system used to identify the airways at night before radio navigation facilities were in place. Never met a more helpful person. Thanks Ned.
Bill Rambow for his many e-mails answering so many questions. Bill designed the incomparable dual panel for the Douglas DC-3 / R4D / C-47. A restored, flyable U.S. Navy R4D at the Mid Atlantic Air Museum in Reading, Pa. was the model for his work. A finer piece of work I've never seen. Thanks for the encouragement, Bill.
Tom H., "Rumple," a gentleman who always sets his work aside to answer the other fellow's questions. I reaped the benefits of his very-methodical air-file testing. He also designed the manifold pressure gauge for the training panel in my Virtual Airline. Tom is very visible on newsgroups and forums patiently answering questions that are asked over and over. Thanks for being there, Tom.
Sarah at Airline History Website for the photo of the KLM Douglas DC-5 which opens the VOR Navigation section. I only recently learned that a DC-5 had ever existed and wanted to include a picture of it. Since Sarah's site has 350 Airline Histories, 1700 Airline Pictures, and 150 Airliners from 1920 to 1999, I knew it would be there. Why is Sarah interested in all this stuff? ... because she's a pilot—and more. She writes software for and sells IFR flight Simulator programs for real IFR training. Thanks Sarah for the great work that you put into your
Chris Sheldon,, from the U.K. He photographed G-AMPZ at Manchester Airport, and it appears here in the IFR Charts section. The aircraft belongs to Atlantic Airways (previously called Air Atlantique) who are based at Coventry Airport. The first letter in the registration number, "G," denotes a U.K. aircraft. Chris exhibits his work at Thanks Chris.
Russ Strine, Mid Atlantic Air Museum in Reading, Pa. Here's another fountain of information. A very busy man at the museum, he pushed his papers aside and spoke with me for an hour on the telephone about aviation in the old days and VORs and NDBs and answered questions that I just wasn't savvy enough to ask. He gave me some anecdotal stuff, too, that you can't find in books. Thanks for your time, Russ, and all the information.
Barry Thomas, Silversmith, who created the magnificent chalice pictured in the section on tracking ADF's inbound. That section's lead-in story centers around Mr. Benjamin Counter's desire to fly to Meriden, Connecticut, 'The Silver Capital of the World' to buy some silverwork. The chalice pictured was not created in Meriden, nor even in the U.S. Barry Thomas is a silversmith in rural Derbyshire, England. Meriden earned the Silver-Capital title in the late 19th century and it is doubtful that it still retains the rights to that sobriquet. Thanks Barry for the great picture, too. More of his masterpieces can be found at
Rod Watson, for his stunning photograph of the Gay Head Lighthouse on Martha's Vineyard, Massachusetts. Rod has visited over 170 lighthouses in the US. and the Lighthouse Gallery section of his website, Rod's Photo Gallery, includes photographs of most of those lights, organized by geographic locations. He photographs more than lighthouses, too. Thanks, Rod, for a great picture.Rod's Photo Gallery
Roland Zuiderveld, from Sweden, for his totally awesome picture of a DC-3 descending out of the clouds at dusk to land. Roland also displays his work Thanks Roland, and if you take any more pictures like this one I want to hear about them.
Many others contributed to my virtual airline webpages and were just as generous. They are identified on that site. Assembling a webpage is so much easier with the assistance of people like these.
With thanks,

Charles Wood 

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