FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1957
1957 - 1424.PDF
514 FLIGHT AIR RADIO DEVELOPMENTS A Year of Consolidation Rather than Invention PROGRESS in the design of new air radio equipment hasnot been particularly marked during the past year—with oneor two notable exceptions. The trend lies rather toward consolidation of gains made in a number of directions.A great deal of attention, both in Europe and America, has, for example, been focused on the provision of an airborne proximitywarning or collision-avoidance device. But most companies engaged in the development of such equipment have met verysevere difficulties; and an authority so eminent as Dr. Morrel, of Bendix Radio, has stated that "an effective self-contained air-borne collision-avoidance system is now and will continue to be out of the question." But the Jet Operations Requirements Panel of I.C.A.O., inparticular, has commented frequently on the need for suitable means of achieving separation between aircraft. It has become something of a fallacy to assume that the col-lision risk is at its greatest in terminal Control Areas and Zones. If anything the reverse is true. With radar surveillance the safeconduct of such controlled airspaces is in competent hands, although airspaces such as the London Terminal Control Zoneand Area are rapidly becoming saturated—a fact which is, in itself, a considerable problem. The greatest danger of collisionbetween aircraft in flight appears to exist either entirely outside controlled airspaces, or else on major trunk routes and, soon,over the North Atlantic. Until the time comes when an efficient anti-*collision aid isavailable the answer would appear to lie partly in the develop- ment of very accurate navigational aids with simple, continuouspresentation. While such aids in themselves will not provide warning of the proximity of another aircraft, they will allow.every aircraft to advise the A.T.C. authorities frequently of its position with a high degree of accuracy. Control can thenoriginate suitable instructions to prevent dangerous collision risks from developing. Apart from the collision problem, the introduction of jet air-craft in numbers on world air routes is going to present problems of another kind. J.O.R.P. has already stressed the problemsrelating to the high rate of closure of potentially colliding jet air- craft; and the lack of conspicuity at high altitudes of such air-craft in the collision sense. Other problems are anticipated in the navigational sense. These particularly include the climbto initial cruising altitude, the use of the cruise-climb technique, and the let-down. Both J.O.R.P. and the I.F.A.L.P.A. have con-cluded that an uninterrupted climb and descent are definite requirements for jet aircraft, and that stringent traffic-controlmethods are going to be necessary. Both these organiza- tions recommend the development of a navigational aidbased on area coverage, providing the pilot with a pictorial cock- pit presentation. In addition, an accurate indication of distance to go is needed. J.O.R.P. also consider the unduly high lateralseparation minima in use on the North Atlantic, noting that the present separation systems would be economically unacceptablefor jet aircraft. In view of these problems and requirements it was more thanencouraging to see displayed at Farnborough this year the new, completely integrated navigational system for contemporary air-craft known as D.I.A.N. This new aid provides in one installa- tion a complete navigation system for long and short ranges, witha very high degree of accuracy. On the face of it, there are good grounds for believing that this aid will completely meet J.O.R.P.and I.F.A.L.P.A. requirements. The first general details of D.I.A.N. were given in Flight for August 23. The ordinary Decca Navigator system is now very well known.Development has progressed to the Mk 10 equipment, in which the earlier zone ambiguity factor has been eliminated. The Mk 10provides fully automatic lane identification, together with zone identification signals enabling the zone identification indicators tobe set manually from radiated information—and not, as before, from dead reckoning information. Another very important factorin the Mk 10 is that by virtue of the multi-frequency pulse technique employed, night effect is reduced and the approvednight range of the new Decca is 240 n.m., instead of 150-180 n.m. as before. The accuracy of the Decca system, of whatever version,is such that, with Flight Log presentation, reduced separation standards for Decca-equipped aircraft flying within U.K. con-trolled airspaces has been approved, and special expediting pro- cedures introduced. Decca's long-range brother, Dectra, has now successfully beenin operation for some months, completely covering the Prestwick- Gander route. Based on conventional Decca principles, Dectraprovides highly accurate tracking and ranging information, again with Flight Log presentation. In fact, the same Flight Log maybe used for a combined Decca and Dectra installation. Essenti- ally, Dectra provides a number of accurately delineated tracksalong a given route, together with distance gone, distance to go and diversion information. On the North Atlantic route thetracks are 5 n.m. apart up to 100 n.m. out from either terminal, and 30 n.m. at mid-route. Such accuracy, when conclusivelyestablished, means that very considerable reductions in present lateral-separation minima for this route will become possible,together with a reduction of the already unacceptable collision factor. In Flight for June 7 an account of the preliminary trialsof Dectra was given. A reproduction of the Flight Log chart used on one crossing revealed an off-track error at 31 deg W ofonly li n.m. As for weights and size, the complete Flight Log, with itsassociated control box and computers, weighs 58 lb and takes up 3.45 cu ft of space. The Mk 8 receiver, complete, weighs 65 lb, The Decca D.I.A.N. system components as displayed (left, below) at the S.B.A.C. Show. The Doppler aerial is on the right of the picture and dials and black boxes on the left. Right, the Marconi AD.2000 (upper) and AD.2100 Doppler radars, also shown at Farnborough. "Flight" photographs flALLY DtSlGNtU HJK
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
