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Aviation History
1996
1996 - 3175.PDF
DISPLAY ADVERTISEMENT SALES UK and EUROPE Display Advertising Enquiries +44(181)6523315 Display Advertising Fax +44(181)6528981 Group Advertisement Director lanBurrows +44(181)6523319 Sales and Events Co-ordinator Lisa Devlin +44 (181) 652 3315 Advertisement Production Display/Classified Howard Mason +44(181)6523267 UK, NORTHERN and EASTERN EUROPE, THE MIDDLE EAST and ISRAEL Senior Area Manager Robin Gordon +44 (181) 652 4998 UK, IRELAND, GREECE, IBERIA, BENELUX, AFRICA COMMENT Area Manager Janice Lowe +44(181)6523316 FRANCE Sales Director France Pierre Mussard Reed Business Publishing France, 15 bis, rue Ernest Renan, 92130 Issy-les-Moulineaux, France. Telephone+33 (1)46 29 4615 Fax+33 (1)40 93 03 37 ITALY Representative Romano Ferrario Gruppo Editoraile Jackson, Via Gorki 69, Cinisello BMilano, Italy. Telephone +39 (2) 6603 4435 Fax +39 (2) 66034367 NORTH AMERICA Vice-president US Sales John Tidy Reed Business Publishing, 3700 Campus Drive, Suite 203, Newport Beach, CA 92660, Telephone+1 (714)7561057 Fax+1 (714)7562514 Sales Director East Coast Robert Hancock Reed Business Publishing, Suite 305,1321 Duke St, Alexandria, VA 22314. USA. Telephone +1 (703) 836 7444 Fax +1 (703) 836 7446 Sales Director Mid-West & Canada Gene Glendinning Reed Business Publishing, 411 Valencia Avenue, Suite 16. Barrington IL60010, USA, Telephone +1 (847) 304 5588 Fax +1 (847) 304 9559 Head Office, Reed Business Publishing, 475 Park Avenue South, 2nd Floor, New York, NY 10016. Telephone+1 (212)6798888; Traffic Manager Debbie Kolb Tel +1 (212) 545 5376 Fax+1 (212)6799455 ASIA, AUSTRALIA Singapore Account Manager Karen Kwan Reed Asian Publishing (Pte) Ltd., No.1 Temasek Avenue, #17-01 Millenia Tower, Singapore 039192 Telephone +65 338 3398; Fax +65 338 3213 CLASSIFIED & RECRUITMENT Classified Advertising Enquiries +44 (181) 652 3811 Classified Advertising Fax +44 (181) 652 4802 Group Advertisement Manager Gareth Pask Sales Manager Sarah Genest International Sales Executives Mo Butttvant. Simon Lees Louise Meikle Lucy Middelboe Classified USA Gail Tavelman Classified Asia/Pacific Lina Rohmat +44(181)6524814 +44(181)770 3010 +44(181)770 3032 +44(181)770 3011 +44(181)770 3027 +44(181)770 3030 +1(212)5455403 +653383398 Publisher Gavin Howe +44(181)652 3675 The full text of Flight Internationaland Airline Business can be found on the following databases: DataStar, F Profile, ESA, Pmdicasts, Textline Mead Nexis and ICA. Details from; tel: +44 (181)302 5101 Published in association with Airline Business by Reed Business Publishing, Quadrant House, The Quadrant, Sutton, Surrey, SM2 5AS, UK Flight International is sold subject to the following conditions: namely, that it is not, without the written consent of the publishers first given, lent, re-sold, hired out or in any unauthorised cover by way of trade; or affixed to, or as part of, any publication or advertising, literary or pictorial matter whatsoever The publishers of Flight International are prepared to accept unsolicited material, but only on the understanding that such material is submitted wholly at the risk of the provider, and that the publishers cannot guarantee the receipt, safekeeping or return of non-commissioned work in any format, including manuscripts, digital data, photographic prints and transparencies. Second-class postage paid at Champlain, New York and additional entries. Postmaster: Send address corrections to: Flight International c/o IMS, Box 1518, Champlain, NY 12919, © Copyright Reed Business Publishing 1996. NEAR ENOUGH? THEUKClMLAVIATIONAuthorityhas investigated the reliability of the global-positioning system (GPS), and found it wanting. GPS, it says, is not reliable enough, in its current form, to be used as a sole means of navigation. In this, the CAA is at odds with the single most powerful civil-aviation authority of all, the US Federal Aviation Ad ministration —but is it also at odds with com mon sense? It has lon% been the dream of aviators to establish their posi tions in space and time with absolute accuracy — and, with the GPS, that dream has come tantalisingly (some would say deceptively) close to reality. In fact, in most branches of aviation other than commercial air-trans port, the GPS has become accepted as the single most important and accurate tool of navigation, whether or not it has been granted that status by sceptical national authorities. The arguments against an unconditional ac ceptance of the GPS are well-rehearsed; the satellites are the property of the US Govern ment, which can downgrade (or even switch off) the service without notice; the reliability of indi vidual spacecraft widiin the constellation cannot be guaranteed; their orbits are such that the quality of the positioning service deteriorates dramatically near the geographic poles. The CAAs latest research seems to prove that such misgivings have a basis in truth. In a sample of 34,419 test points, outages detected by the onboard avionics were experienced in 759 (2.21%) cases and, more worryingly, there were undetected outages in another 487 (1.41%). Ac cording to this test, only 96.38% of the GPS position reports were correct. The results sug gested that a receiver would go fewer than 60h between outages. The last time that the air-transport industry relied on a piece of technology which was appar ently that unreliable was in the 1950s, when an airliner powered by four of the powerful but complex Wright Turbo-Compound piston engines could virtually be guaranteed to suffer an engine failure in the course of a return transatlantic trip. The failure of a sole-means navigation system could be a traumatic event—but would it really be so? For a start, not since the dawn of avia tion, when an aviator was lucky to get safely airborne at all, far less worry about doing anything more sophis ticated in navigation than use the Mkl eye ball, has the average pilot relied solely on one means of naviga tion. Even when using primitive radio-navi gation aids, the pilot would check back on visual cues, and no transatlantic pilot to day would rely on a sin gle inertial-navigation system. Now, it seems, he could be asked to rely on one system — the GPS. Does this make sense? The military it self tends to use one or more inertial-naviga tion systems (INS) as a back-up. The concept of using a single system without a back-up seems alien to an industry which has adopted caution as a watchword. It is not impossible to conceive a navigation system which does not rely entirely on satellite-derived data as its primary feed, but to to check and aug ment accuracy. A system combining an INS withi the GPS should be inherently more reliable than one which relies on the GPS alone. The industry does need the GPS, or some other ultra-accurate navigation system, sole- means or otherwise, to meet its demands for greater use'of the airspace available. Without positional accuracy measured in a few metres, rather than hundreds or even thousands of metres, the concept of vertical and horizontal separations reduced to hundreds of metres can never be realised. The only available sources of such data are the.satellite-based systems, a fact which those who -would question the reliability of GPS would do vvell to remember. The GPS is not perfect — and it will not remain unaug- mented in accuracy, availability and integrity for long — but it is much closer to perfection than anything which has gone before. • "Pilots would check back on visual cues, and no transatlantic pilot today would rely on a single inertial- navigation system." FLIGHT INTERNATIONAL 4 - 10 December 1996 3
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