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Aviation History
1960
1960 - 0525.PDF
PLIGHT, 15 April 1960 525 6NT SYSTEM SURVEY Decca Developments THE ICAO Council was due to decide for or against the adoptionof DMET as an international short-range aid in Montreal last Friday, and news may reach us in time for inclusion in a late-newspage of this issue. Meanwhile Decca have announced a "major breakthrough"with the Omnitrac computer, which is to be capable of converting the normal Decometer readings for pictorial presentation on anundistorted xy grid. The device is claimed to be small, simple and reliable. Decca Group has been working towards this solutionfor some years and Omnitrac is indeed a major breakthrough, not only for the conversion of Decca outputs to orthomorphic grid butfor similar processes in numerous other applications. Addition- ally, rectilinear Decca presentation can now be combined withthose from other position-fixing systems and auto-steering devices in a wide variety of vehicles. Correlation of marine radar withshore-based navaids, for example, and position-fixing for survey work, would be greatly simplified. Announcing Omnitrac, Decca stated that "we have recentlyfound a manipulation of the mathematics of this conversion which we believe has remained undiscovered for the twentyyears or so during which hyperbolic systems have been develop- ing and we are in the process of producing the first model of thecomputer in airborne form. Knowing the digital and analogue solutions to this problem that have so far been put forward, weare confident our techniques will prove to be so advanced that our digital computer will have a fraction of the complexity of itsforebears, a bulk and weight that will compare favourably even with analogue devices of much lower accuracy, and a price whichwill make it available to a very large number of users in all fields." In the House of Commons on April 4, Mr Sandys, Ministero^ Aviation, replied to two written questions by quoting an official letter sent to the Secretary General of ICAO by the UK repre- Latest picture of Ferranti Airpass, ready for test installation in a Canberra. Left to right, the black boxes are the hand controller, attack sight, radar display, fire-control computer and radar. Airpass is shortly to enter service with the Lightning and is fitted to export Saab Drakens. Ferranti have also developed the attack radar for the NA.39 sentative in Montreal, commenting on the recent Federal AviationAgency report on helicopter operations with Decca and the trial of a Mk 10 receiver in a Convair C-131. (Comments on thesereports appeared in Flight for March 4.) While expressing some satisfaction with the helicopter opera-tions report, the UK representative to ICAO regretted that the UK felt "bound to observe that the supplementary report on DeccaMk 10 suffers by comparison with the principal document and cannot be accepted in the same category of objective reporting."The trial had been "hasty and ill-conceived" and the UK was "unwilling to allow the issue of the supplementary report at thepresent time and in the present circumstances to pass without comment." The letter drew attention to certain features of thereport [which have already been commented on in Flight] and concludes that there are "serious doubts on the value of the reportfrom any aspect." The UK representative asked that his com- ments should be brought to the notice of those ICAO member-States who had received copies of the original FAA report. Although the Federal Aviation Agency is firmly opposed to theadoption of Decca as an international short-range aid and is indeed committed to Vortac as the "common system" in the(US,its attitude to the use of Decca for helicopter navigation is very different. The Phase I trials which were recently reported onhave now been succeeded by Phase II: these trials will involve several thousand hours of IFR helicopter route-flying withmulti-engined helicopters controlled from a special traffic centre in the New York area and operating in close proximity to theexisting fixed-wing airways. A review of the Phase II programme remarks that "the jetage is here—the helicopter age is almost upon us." Wider use of helicopters has been retarded for several years, the statementcontinues, by lack of suitable powerplants, but these are now becoming available and, together with other technologicalimprovements, "will result in an explosive expansion in the use of helicopters." It is noted that scheduled helicoDter carriersflew 628,000 revenue passenger-miles in 1955 and "4,885,000 in 1958. The number of passengers carried is increasing 80 timesfaster than that in fixed-wing transports. Helicopters account for no less than 16 per cent of all operations at La Guardia Airport. The Phase II schedule called for trials to begin last Novemberwith the installation of special equipment in IFR helicopters. In December, initial familiarization flying was to begin andscheduled operation in VFR weather was to start on January 11. On April 1, two weeks ago, scheduled services in actual IFRconditions or with one of the pilots "under the hood" were to start. The aircraft wer: a twin-engined Sikorsky H-37 of theUS Army and a US Marine HR2S. Vertol are scheduled to phase-in twin-turbine helicopters in the future and one OmegaBF-12 twin-piston-engined light helicopter was to join the trials if its FAA certification programme proved satisfactory. Sikorsky, The CL.ll Rotorace gyro now being produced by Sperry in Britain
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