FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1949
1949 - 1996.PDF
FLIGHT, 15 December 1949 CIVIL AVIATION NEWS.. ASSESSING OPERATING COSTS WITH the dual objects ot assisting operators to assess thesuitability of any aircraft for their particular needs andof providing a ready means of comparing the operating econo- mics of competitive types in a standard set of conditions, theSociety of British Aircraft Constructors has evolved a standard method for the estimation of direct operating costs. Recentlyissued in brochure form under the title Standard Method for the Estimation of Direct Operating Costs of Aircraft, the schemehas already been featured in handbooks describing new British airliners and, additionally, has been made available to theAircraft Industries Association, the American counterpart of the S.B.A.C. First suggested by the S.B.A.C. export committee, the planwas evolved by a special committee of the Society's technical board and the major part of the task was completed in a littleover a year. While admitting that any system of this kind must have a certain amount of latitude and can only be generalin scope, the Society considers that the method closely approaches the ideal, because it includes formulae of a kindwhich, after reference to their derivation, allow the assump- tions to be adjusted to meet any special circumstances. The method deals only with direct operating costs. Onlyone exception to the principle of excluding indirect costs has been made, in that workshop overhead expenditure is includedin the labour rate quoted for airframe, power-plant and air- screw maintenance and overhaul. In the preparation of the standard method, the Society con-sidered three distinct expenditure headings: (a) annual costs (expressed as an hourly cost by dividing by utilization), com-prising obsolescence and insurance, (b) fixed hourly running costs, comprising maintenance and overhaul expenses, and(c) hourly running costs—which vary with the speed or stage- length under consideration—including aircrew cost, fuel and oiland landing charges. An addition of all items under headings (a) to (c) then gives total hourly cost from which other costscan then be resolved. The cost per ton mile, for instance, can be found by dividing the total hourly cost by the stage-speed and the payload appropriate to the stage. This unit immediately gives a measure of the overall commercial efficiencyof the aircraft and, for purely freight-carrying aircraft, is a suitable final expression. The cost per passenger mile (assuming that each lb-weightof payload, whether it be freight or passengers, will cost the same to transport), can be simply obtained by multiplying thecost per lb-mile by the weight of the passenger unit. The unit costs "derived are evaluated for a 100 per cent load factor.The effect of smaller load factors can be obtained by dividing the standard unit cost by the appropriate percentage loadfactor. The formula for setting out the costs summary is containedin the brochure. In each instance the basis of "calculation is shown and only the blank spaces need to be filled in. Forexample, to determine the annual obsolescence of the equipped airframe and spares, only the initial cost of the equipped aii-frame has to be inserted in the two blank spaces of the formula under that heading. The same formula applies to the powerplant and spares and to airscrews and spares, with the addition of the number of engines and airscrews respectively. To discover the cost of insurance it is only necessary toinsert in the appropriate places the first cost of the. aircraft and the number of seats. The brochure also describes how thecosts set down have been derived. For example, after consul- tation with operators, the first-line life of an airliner wasassumed to be eight years, with a residual value of 20 per cent at the end of that time. Similarly, the number of revenue-earning flying hours per year was quoted at 3,000, but any constructor who feels that this figure is too high or too lowmay calculate costs based upon some other figure provided that he details his reasons for making the departure from the stan-dard. Other averages include a rate of six per cent of the aircraft's first cost (including spares) for insurance (includingthird party liability), and a /15-per-seat rate for passenger liability. A study of operating statistics showed that the average costof airframe maintenance can be fairly represented as propor- tional to the equipped-airframe weight. The total labour rate(including 200 per cent for workshop overheads) is assumed as being 10s per man-hour. The total hourly cost of us per1,000 lb equipped airframe weight (the equipped weight is defined as "Basically Operational Weight" minus total "PowerWeight"—i.e., less engines, airscrews and all power acces- sories) is then based on the assumption that 0.9 man-hoursand 2s worth of materials are expended on maintenance for each 1,000 lb every flying hour. The formula for estimating maintenance cost of the powerplant assumes an average of 0.9 of the permitted interval between major overhauls. Methods lor calculating airscrew-maintenance and overhaul and crew-costs are also shown. Fuel assessments are in two categories, the first being the equivalentof the fuel consumed and stage time (to ascertain the cost per flying hour), the second being a calculation of fuel carried(to ascertain the payload for the appropriate stage-length). Cost of oil consumed has been taken as 0.04 of the cost offuel consumed. The brochure contains a "worked example" showing theapplication of the various formulae and a set of graphs showing cost per flying hour; payload, speed and time; cost per nauticalmile, cost per ton nautical mile and passenger nautical mile. A set of definitions designed to remove any ambiguity whichmight arise in the interpretation of various terms is also included. Designed principally to apply to piston-engined aircraft, thenew method nevertheless offers guidance on certain aspects of turbojet- and turboprop-powered aircraft and, when technicaland operational development requires it, the method will be revised to bring them fully within its scope. BREVITIES FT is understood that Turkish Airlines have decided to-«- purchase ten British Helicopters for service in remote parts of Eastern Anatolia, where excessive snowfalls render landcommunications extremely difficult during the winter months. * • *It has been announced that Air Marshal Sir Roderick Carr, who has been M.C.A.'s Divisional Director for the Londonand South East Division during the past three years, is to retire from that position on January 31st.* • * According to an article in the November issue of the Glenn L.Martin company's journal, Northwest Airlines are now operat- ing their Martin 2-0-2S at a direct cost of 14.85 cents per avail-able ton-mile. This is said to compare with a direct cost of 18.83 cents for the DC-3. In the two years during whichNorthwest has used them, the 2-0-2S have flown 12,275,635 revenue miles and 223,255,000 revenue passenger-miles.* * # The first certificate authorizing a foreign repair agency toperform work on United States aircraft has been issued by C.A.A. to the Compania Mexicana de Aviacion, an affiliatedcompany of Pan American Airways in Mexico City. Certifi- cation of s'Jch foreign stations is permitted, under the termsof an amendment to the Civil Air Regulations, if the personnel are deemed competent by the C.A.A. (even though they do'not hold licences issued by that authority) and provided that the stations comply with technical requirements identical tothose for their U.S. counterparts. * # • A total of 2,087 civil aircraft registrations has been reportedby the Civil Aviation Division of the Canadian Department of Transport. Of these, 1,468 are commercial aircraft and 619are privately owned. Licences for airports amount to 369, and the total of personnel licensed includes 4,158 pilots. * * * B.O.A.C. has reported that the total of revenue passengersincreased by over 12,000 during the first nine months of this year. Cargo carried increased by over 12 per cent, from 2,660to 2,984 tons, but the total of mail showed a decrease of 7.8 per cent as compared with the same period of last year. * * » Air Marshal Sir John d'Albiac, commandant of LondonAirport, was one of the passengers on the first flight of the B.O.A.C. Stratocruiser service between London and New Yorkwhich left London on December 6th. It is understood that the purpose of Sir John's visit will be to study the workingof the air traffic control and passenger facilities at Idlewild.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
