are w1derspread in particular dealing with operations to a number of offshore installations.
mission over the newly-created public data line network to more than forty terminals.
All trunk route airports are equipped with ILS's with 10 of the busiest airports being equipped with two cat. 1 ILS's conforming with ICAO requirements. STOL airports are equipped with ILS localizer and DME. except for two airports which rely genera lly on ND B's. A tota l of 23 VOA stations provide for complete ai rway coverage. Two of these VOA stations are of the Doppler type provided by Plessey. A large number of NDB's also serve air navigation both 1n the en-route and terminal areas. A total of 25 DME systems by FACE Standard are co-loca ted wi th ILS's for landing purposes and with VOR's for en-route. It is planned that in the coming years the number of ILS' s will in-. crease while the number of VOR's and DME's will be doubled to enable the authorities withdraw some of t he NDB's.
The manufacture of Norwegian ILS's started in 196 7 based on the development work conducted by the research establishment ELAB. Manufacturers NERA began deliveries first and continues development efforts. When finally NERA merged with Elektrik Bureau. the company Norsk Marconi continued to manufacture ILS making th e ILS exports of the coun try to cover all versions of glide slope and localizer antenna systems. including two-frequency systems. Special mention must here be made of the wide apperture glide slope antenna. for wh ich only about 50 meters of fla t terrain should suffice. Presently a two-frequency local izer antenna system with 24 antennas is under development. A newly constructed glide slope antenna mast of fibreglass reinforced by plastic will meet t he long sought requirement for a frangible construction. This mast is now in operation at Oslo Airport. Fornebu . Recent orders for deliveries of Norsk Marconi ILS to airports in the United Kingdom and Germany ha s lead to great opt1m 1sm for larger internationa l orders. The concept of logperiod1c localizer antennas. which were first introduced on Norwegian ILS. has now won genera l acceptance in the USA and United Kingdom. Another company. Delcom Elektra. has recently delivered the first equipment of its newly developed DM E to the Norwegian authorities. It is completely transistorized 1 kW outpu t power version - and is based on modern microprocessor technology for monitoring and control. Delcom Elektro has previously delivered its NOB-monitor rece iver DC-450 to several coun tries. 1nc lud1ng to UK NATS The latter delivery also comprised the Nava1d morse code IDENT monitor DC-455F . All Norwegian NDB 's are equ ipped with DC-450 for remote monitoring. Delcom 1s presently developing an automatic d1g 1tal measurement and con trol system for nava1ds. radars and commun1cat1on stations. Th is real tim e integrated monitor system will provide the technicians with comprehensive data for im proved ma intenance and operation of the various systems. Delcom Elekt ro. together wi th ELAB and the German Nava1d com pany Standard Elektri k Lorenz. are presently studying the application of th e Germa n DAS for off-shore opera tions (DAS = DM E based azimuth system. which 1s
Navaids in Norway by J. A. Stenstadvolden (chief engineer Aeronautical SeMces. Norway)
Av1at1on plays a most important role 1n Norwegian domestic and international communications. This may be due to the large distances over rugged terrain and extreme climatic conditions which are challenging the means of transport. A total of 46 airports th roughout Norway serve scheduled airline services of which 21 serve trunk routes with a runway length of 1 600 meters or more: the remaining are generally STOL airports with a runway length of 800 meters. The main airline operators are Scandinavian A1rltnes System (SAS) and Braathens SAFE on trunk routes. Wyder0e Âˇs Flyveselskap 1s operating STOL services with Norv1ng and Nordsi0fly on commuter services. Helicopter services
Air traffic control In the field of air traffic control a large prog ramme has been adopted by which it will provide prim ary and seconda ry radar coverage throughout most of the country. A terminal radar at Stavanger 1s now nearing completion and rada r work at Bremen 1s expec ted to be completed soon. A completely new AFTN system. developed by Norsk Data and Siemens is expected to be installed 1n 1982 . This system 1s based o n a central computer data store with high-speed digital trans-
Fornebu Conventional VOR w ith special antenna with dome for snow protection. 38