Air Almanac Research Articles

P. V. H. Weems: A Personal Tribute

The recent death of Philip Van Horn Weems, at the advanced age of 90, has removed from the field of navigation one of its most outstanding and colourful personalities. His contributions, made over a period of more than half a century, have ranged over almost every aspect of navigation: practising navigator, instrument inventor, pioneer of the GHA form of Nautical Almanac and of the first Air Almanac, introducer of the Star Altitude Curves, brilliant expositor (as his books so clearly demonstrate), successful business man who trained many thousand navigators through his training schools and correspondence courses – he devoted his whole life to navigation with boundless energy and contagious enthusiasm.This is not the place to give the factual details of his life, or to put on record his many achievements, both inside and outside his professional career. Many of his most lasting and significant contributions to the practice of navigation, although so familiar to myself, can only be appreciated by a detailed study relative to the contemporary ‘state of the art’; Weems was, above all else, an innovator of ideas many of which were developed by others and which deserve a fuller and more technical treatment.A brief summary of his career follows. Weems, left an orphan at an early age, had a hard life on the family farm in Tennessee, with little formal education.

Marine User's Modifications to the Air Almanac

Marine User's Modifications to the Air Almanac

The Precision of the Air Almanac and the Sight Reduction Tables, A.P. 3270

Ever since the introduction of the Air Almanac and the Astronomical Navigation Tables, requests have been received for information as to the errors that can arise in their use. Estimates of error, for particular combinations, were made on several occasions and, in 1947, the calculation was systematized; but the methods and results were not published. It is now probable that the Sight Reduction Tables for Air Navigation, A.P. 3270 (H.O. 249 in U.S.A.), and possibly the Air Almanac, will increasingly be used for surface navigation and it therefore seems desirable to put on record a precise statement of the errors that can arise through their use. The earlier work has accordingly been modified for the changes in the publications.

H.O. 249 AND THE NEW AIR ALMANAC

NAVIGATIONVolume 3, Issue 7 p. 239-242 H.O. 249 AND THE NEW AIR ALMANAC John Dohm, John Dohm Pan American Navigation ServiceSearch for more papers by this author John Dohm, John Dohm Pan American Navigation ServiceSearch for more papers by this author First published: March 1953 https://doi.org/10.1002/j.2161-4296.1953.tb00661.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume3, Issue7March 1953Pages 239-242 RelatedInformation

Air Almanac

Journal of Geophysical Research (1896-1977)Volume 57, Issue 1 p. 146-146 Air Almanac AGU, AGUSearch for more papers by this author AGU, AGUSearch for more papers by this author First published: March 1952 https://doi.org/10.1029/JZ057i001p00146-04AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume57, Issue1March 1952Pages 146-146 RelatedInformation

Unification of the Air Almanac and the American Air Almanac

As from 1953 theAir Almanacand theAmerican Air Almanacwill become a single publication, under the title of theAir Almanac. It will be produced jointly by H.M. Nautical Almanac Office of the Royal Greenwich Observatory, Herstmonceux, and the Nautical Almanac Office of the U.S. Naval Observatory in Washington, to meet the general requirements for air navigation in the United Kingdom, the United States and Canada. TheAir Almanacwill be printed and published separately in the United Kingdom and the United States but the two publications will otherwise be identical.

UNIFICATION OF THE AIR ALMANAC AND THE AMERICAN AIR ALMANAC

NAVIGATIONVolume 3, Issue 1-2 p. 9-11 UNIFICATION OF THE AIR ALMANAC AND THE AMERICAN AIR ALMANAC G. M. Clemence, G. M. ClemenceSearch for more papers by this authorD. H. Sadler, D. H. SadlerSearch for more papers by this author G. M. Clemence, G. M. ClemenceSearch for more papers by this authorD. H. Sadler, D. H. SadlerSearch for more papers by this author First published: September‐December 1951 https://doi.org/10.1002/j.2161-4296.1951.tb00594.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume3, Issue1-2September‐December 1951Pages 9-11 RelatedInformation

Unification of the “Air Almanac” and the “American Air Almanac”

Unification of the “Air Almanac” and the “American Air Almanac”

The Earth's Magnetic Field

The Institute has now completed two years of its existence. The papers which have been read before it during these two years have covered a wide range of subjects and have served to emphasize the many ramifications of the science of navigation. Because of the high speed of modern aircraft, air navigation presents more problems and of greater variety than surface navigation, but even on the problems of surface navigation there has been ample scope for a wide range of discussion. The Institute has taken a prominent part in the discussion of the proposals for the revision of the Abridged Nautical Almanac. It might with some reason have been supposed that there was nothing more to be said on the methods of reducing astro-sights and determining position at sea. The problem is perfectly straightforward and there is a limit to the number of different ways in which the spherical triangle can be solved. But the essential basic data can be presented in a variety of ways, while there are many possible methods of presenting tables for the solution of the spherical triangle. The decision to use Greenwich hour angle instead of right ascension in the Abridged Nautical Almanac has followed its adoption in the Air Almanac; the revised Almanac will have an entirely different format from the present, while the methods of reducing sights must be correspondingly modified.

The Possibility of an Altitude-Azimuth Almanac for Air Navigation

It is generally agreed that the increasing speed of modern aircraft, together with the availability of short-range radio and radar aids, necessitates a fresh approach to astronomical methods; less accuracy can be tolerated in the calculations but greater speed is essential. There are three stages after observation : the derivation of the position of the heavenly body observed, usually from the Air Almanac; the solution of the astronomical spherical triangle, usually by means of reduction tables ; and the resulting plotting of the position lines and fix.

Astronomical Navigation in the Air

A DISCUSSION on methods to produce speed and accuracy in the practice of astronomical navigation in the air was organised by the Institute of Navigation, and held on June 17 in the lecture hall of the Royal Geographical Society, under the a of the astronomer royal, Sir Harold Spencer Jones. In his introductory remarks Sir Harold directed attention to the fact that it was in the same hall, some twelve years earlier, that the Air Almanac had been first discussed in public.

Thurlow Navigation Award for 1948 : Mr. D. H. Sadler

THE Thurlow Navigation Award of the United States Institute of Navigation was founded in 1946 by Mr. Sherman Fairchild (president of the Fairchild Camera and Instrument Corporation, Inc.) in memory of the famous air navigator Colonel Thomas L. Thurlow, who was killed in an air accident in 1944. The award is made each year to the person who, in the opinion of a representativo selection committee, contributes most to the science of navigation. The first award, in 1946, for the year 1945 was made to Wing-Commander K. C. Maclure, who was navigator of Aries on its flights to the north magnetic and geographical poles. That for 1946 was made to John A. Pierce, the originator of the Loran system of radio hyperbolic navigation, and that for 1947 to Dr. John C. Bellamy, inventor of the Bellamy drift indicator. The award for 1948 has been made to Mr. Donald' H. Sadler, superintendent of H.M. Nautical Almanac Office, in recognition of the work of the Office in the field of air navigation, particularly the production for the Royal Air Force of the "Air Almanac" and the "Astronomical Navigation Tables". More recently, the Office, which is part of the Royal Observatory, has been completely redesigning the "Abridged Nautical Almanac", so as to tabulate Greenwich hour angle instead of Right Ascension, and the new form will simplify the sea navigator's task. Because the new methods involve change of syllabus at the navigation schools and other changes, the introduction of the "Almanac" will be deferred until the year 1952. Mr. Sadler joined the Nautical Almanac Office in 1930, after doing research at the University of Cambridge, and was promoted to the post of superintendent in 1936. He was secretary of the Royal Astronomical Society during 1939–47 and vice-president in 1947–48. He played a large part in the formation of the [British] Institute of Navigation.

A Critical Table for Sextant Corrections

It is the present usage by the National Physical Laboratory and the Trade to give, on its Certificate, the ‘constant’ (graduation and centring) errors of a sextant only at stated points on the scale. If these errors are of a magnitude which is worth while applying as a correction, this usage is not quite what the user requires. The N.P.L. Class A Test, issued for instruments reading directly to 10″ (or o′·2 in the case of decimal subdivision) allows combined graduation and centring error up to 40″ or 4 scale divisions of the micrometer or vernier; the Class B Test for instruments graduated to 20″ permits such error up to 2′ or 6 scale divisions. Thus, even with instruments that pass these tests, it may be worth the marine navigator's while to apply the error as a correction. What he wants to know, however, are the limits of such errors as are worth his while to apply. In other words, he requires a Critical Table of Corrections, of the type used in the Air Almanac and in certain mathematical tables by L. J. Comrie, by whom, it is understood, the method was introduced.

The Navigational Work of the Nautical Almanac Office

Almost ten years ago (14 March 1938), in this same lecture hall, the Astronomer Royal, our newly elected President, opened a discussion on the recently published Air Almanac. That meeting, held under the auspices of the Royal Geographical Society, can justly be said to mark an epoch in the application of astronomical methods to air navigation in this country; but it was remarkable in other ways too. First, it provided that opportunity for criticism, by users and by others interested, of the provision to be made for astronomical navigation in the air, which it is hoped the Institute will provide for all aids to navigation. Secondly, the preparation of the Astronomical Navigation Tables was first announced; this may not appear very remarkable in itself, but it was the first time, since the days of Nevil Maskelyne, fifth Astronomer Royal, that the Nautical Almanac Office had prepared any major tables for the reduction of navigational observations!

Star Recognition

THIS book supplies a lot of useful information for those engaged in air-navigation star-work, and follows the procedure adopted in the "Air Almanac", dividing the stars into three Lots: Lot 1 contains 22 main stars which are printed in capitals; the 13 stars in Lot 2 are in italics, and Lot 3 contains 15 stars considered third class for air navigation; but Benetnaseh and Polaris are now included among the 24 main air navigation stars, Polaris, though only second magnitude, being considered much more valuable to the navigator than any other stars. Very full directions are supplied for the identification of the stars in various quarters of the heavens, and some space is also devoted to a description of the appearances of the navigational planets, Venus, Mars, Jupiter and Saturn, and to the method for recognizing them.

NOMOGRAMS FOR COMPUTING TIDAL GRAVITY

It is possible, by the use of a nomogram devised by Dr. James B. Friauf (Journal of the Franklin Institute, Vol. 232, pp. 151–174, 1941) for the solution of spherical triangles, to make simple nomograms for the computation of tidal gravity. Two types of such nomograms are explained and illustrated. The first is for computations at a fixed latitude on the earth; the second is for computations at a fixed point. With the second type the computation of tidal gravity is reduced to a simple routine matter, especially if The American Air Almanac is used as the source of the astronomical data needed. The accuracy of these nomograms is studied and a comparison is made of this new method with that recently devised by Dr. Adler (Geophysics, Vol. 7, pp. 35–44, 1942).

The Air Almanac, 1939, January–March

THE British “Air Almanac”, an almanac specially adapted to the requirements of air navigation, was published for the first time for the last quarter of the year 1937. A review of this publication appeared in these pages. Experience with the almanac in its original form showed the desirability of certain changes. These changes were required, in the first place, in order to shorten the time occupied in working out the results, and, in the second place, to reduce the amount of turning over of pages, because the air navigator often has very cold fingers. Another consideration was the numbing effect on the brain of a long flight; in order to reduce the possibility of error, it was desirable to make the working out of the results so far as possible a matter of pure routine. To meet these requirements, the “Air Almanac” has been completely remodelled. As compared with the original almanac, in the remodelled edition the amount of interpolation has been reduced to a minimum: the number of separate tables that have to be referred to has been reduced, so avoiding turning over pages; and the way of extracting the required information has been standardized.

The Air Almanac: Discussion on the New Form of Nautical Allowance for Rapid Position Finding

The Air Almanac: Discussion on the New Form of Nautical Allowance for Rapid Position Finding