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Aviation History
1937
1937 - 1948.PDF
62 FLIGHT. JULY 8, 1937. Commercial Aviation TELEPHONY or ? Some Trenchant Comments on the Telephony versus Telegraphy Business By W. E. CROOK, A.M.I.E.E., A.F.R.Ae.S. I N the application of wireless to air navigation there has always been a mild battle between telegraphy and tele phony. Telegraphy, however, has obtained so sweeping a victory that the adherents of telephony may soon find them selves in much the same position as members of the Jacobite Society—regarded by everyone else with a sort of amused tolerance. Telephony has certain apparent advantages, but these advantages will hardly stand investigation. First, it is often said, telephony is quicker. Your competent telegraphist may work at an average of twenty words a minute, whereas carefully enunciated speech is delivered at least four times as fast. As an arithmetical fact, this statement is un assailable, but in reality it is of no importance because the telegraphic code reduces messages to the shortest possible length. As an example, take a position report as it appears in telephony and telegraphy with the help of the "Q" code: Hallo Croydon So-and-so's G-EXYZ calling Passing Bexhill Making Berck Height one thousand metres Below cloud Over—or—GED de GEXYZ QTH Bxl QAB Berck QBH 1000 AR. The telegraphy version can be sent comfortably in 20 to 25 seconds The telephony version can be spoken in 15 to 20 seconds. At the very best then, in this instance, telephony is only about 05 per cent, faster. In some cases it is no faster and might even be a little slower—as in these: Hallo Croydon So-and-so's G-XYZ calling Request mag netic reciprocal bearing please Over. GED de GEXYZ QDM? It may be possible to gabble into the microphone and beat the operator to the finish, but anyone who has experienced telephony from an aeroplane knows that the inevitable result of such a proceeding would be a request for a repetition. It is normal enough for the spoken word to be misunderstood when the people conversing are face to face. When the speech is double mangled en route by the transmitter and receiver the likelihood of misunderstanding becomes so alarming that all really important words have to be laboriously spelt out by the use of an incredibly clumsy phonetic alphabet. The mis understanding of a telegraphy signal is a virtual impossibility and where messages have to be written down, telegraphy scores heavily on the grounds of both speed and accuracy. The second point often made in favour of telephony is the fact that the people using it do not have to learn Morse. The mastery of Morse is tedious, but not particularly difficult and is a purely mechanical process. There are many men who read and send Morse for several hours daily and get less than £3 a week for it. If pilots earning the best part of £1,000 a year and more were suddenly given an ultimatum to learn Morse within a year, it would be no great hardship. From the point of view of the wireless technician, the aban donment of telephony would be an unmixed blessing. It would simplify the transmitter considerably, the receiver to a less extent, and would save quite a lot of weight. It might be possible to improve telephony so much that perfect reproduc tion is obtained. The pilot in the air and the control officer IMPRESSIVE inaugural ceremonies were held at both Don-caster and Liverpool Airports on June 30. The Royal Dutch Air Lines (K.L.M.) were opening the Liverpool-Don- caster-Amstcrdam service and North-Eastern Airways were inaugurating the link line between Doncaster and Manchester, Hull and Grimsby, while both companies were celebrating the fact that the existing line of N. E. A. to Aberdeen and Perth now links up with K.L.M. at Doncaster. At Doncaster, guests were received and entertained by Capt. Spry Leverton and Mr. C. Kauffmann of K.L.M. and Mr. Jacques of N.E.A., whilst Lord Grimthorpe, chairman of the latter company, arrived, piloting his own machine, when the joy riding and other jollifications were at their height. K.L.M. are using Douglas D.C 2s on the line this year and Comdr. Moll arrived at Doncaster at about 10.30 with one of these machines. He presented flowers to the Mayoress of Don caster and explained that they had been gathered in Holland that morning. Some 150 prominent citizens from Doncaster and neighbouring cities flew in the D.C.2 and in the N.E.A, Airspeed Envoy. Guests who had flown by the K.L.M. on the ground may be able to converse as if in a drawing-room, but would that be a great advantage? It would probably tend to prolong conversations. The more rapid speech would tend to increase the possibility of error. In the event of misunder standing or dispute, there would be no wireless log to prove who was right. And much more important still, unless some entirely new principle of wireless communication is discovered, telegraphy will still be required for the longer distances, the range of a telephony signal being so much shorter for a given power. The wireless operator is, therefore, still wanted and the telephony apparatus becomes a mere luxury. I do not, of course, include the wireless telephone apparatus which may, on large machines at some future time, be provided for pas sengers' use. But for navigational and air traffic organisa tion work, telegraphy fills every possible need and does so much better than the spoken word. The most difficult case is that where the crew consists simply of the pilot and it has been taken for granted that in such circumstances telephony is the only solution. I doubt it; a comparison of the processes involved will show the fallacy of such an idea. Convincing Comparisons No matter whether telegraphy or telephony is used, the pilot will have to manipulate a Send /Receive switch, which is all he need do after the preliminary receiver tuning. In trans mitting, he probably holds the microphone in his right hand, so he might just as well work a conveniently placed Morse key instead. In receiving messages, writing is obviously out of the question, and the wireless traffic must be restricted to the briefest possible routine signals. For a man who is accus tomed to reading Morse and is really familiar with the pro cedure used, it is just as easy to read and memorise a couple of " Q " signals as it is to listen to and memorise some spoken words. One might justifiably claim that it is easier, because the reception of speech in the air is notoriously difficult, mainly on account of the general poor quality of telephony in air work. When all has been said, the root cause of the whole argument is the reluctance of airline pilots to make themselves competent operators. In some cases, they have not had much oppor tunity of doing so. In all cases they have to learn quite a lot about flying and blind flying and engines and navigation and meteorology and instruments. Wireless operating is pretty nearly a whole-time job, and it does seem rather a tall order to expect a ship's captain or first officer to be a wireless oper ator as well. Nevertheless the doctor, the engineer and the lawyer, when qualifying for their professions, have to absorb far more learning than the commercial pilot is called upon to do. The unalterable peculiarity of an aeroplane is the necessity for limiting its crew. The operating side of aviation is coming to be regarded as a profession and, combining these facts, 1 suggest that the pro fessional pilot of the future—and even of the present—must and should regard absolute competence in wireless operating as one of his essential qualifications. from Holland flew on to Perth by North Eastern Airways. Later in the afternoon the D.C.2 flew on to Liverpool, where a large crowd was assembled. Comdr. Moll again said it with flowers and the Lord Mayor of Liverpool made a short speech of welcome. Capt. Spry Leverton, replying on behalf of K.L.M., said that though traffic had not been very good during the previous season K.L.M. had faith in the public and had given of its best—the fast Douglas which enabled Liverpool people to fly to Holland and back in a day and to reach twenty-seven European cities in an easy day's flying. He hoped Liverpool would respond by filling the machines, in which case the company would put on more services and, later, even faster flying stock. The Mayor of Wallasey then spoke, urging greater air- mindedness and pointing out that the enterprise of the K.L.M. deserved the fullest support. Short flights were then made by 150 or 160 guests in the Douglas. The actual service, which links up with several important lines of Railway Air Services at Liverpool, started on the fol lowing day, July 1. TWO INITIATIONS
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