CIRCULAR TRAILING VORTICES 1969 INTERNATIONAL ClVlL AVIATION ORGANlZATlOW w MONTREAL CANADA Reprint of material on the subject of aircraft trailing vortices, kindly supplied by the Governments of Canada, United Kingdom and the United States of America for inclusion in this Circular. Published by authority of the Secretary General
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TABLE OF CDJTENTS Foreword ................................. 1 Flight measurements of the vortex wake behind a Convair 880 - Report of the National Aeronautical Establishment, Canada 3 ........ A flight investigation into the persistence of trailing vortices behind large aircraft - technical note of the Royal Aircraft Establishment, Farnborough, England ................... 13 Aircraft vortex wakes and their effects on aircraft - current paper of the United Kingdom Ministry of Aviation Aeronautical Research Council 3 5 ...................... Turbulence caused by large aircraft - Aeronautical Information Circular issued by the Board of Trade, Civil Aviation Department of the United Kingdom 75 ..................... Wake turbulence - Advisory Circular issued by the Federal Aviation Agency, United States of America 7 7 ................
FOREWORD The ICAO Fifth Air Navigation Conference Montreal, November - December 1967, Doc 8720 AN-CONF/ recognized that turbulent wake was potentially dangerous to other aircraft and expressed the view that a more positive approach should be adopted towards making adequate allowances for turbulent wake effect in determining separation between aircraft in the approach and take-off phases of flight. The Conference also recognized that it was not practical, in view of the present lack of knowledge on the subject of turbulent wake, to develop precise criteria concerning the time taken for trailing vortices produced by an aircraft taking off or landing to decay to the point where they are no longer a threat to other aircraft. Nevertheless, it felt that the material published on the-various studies made to date contained useful information on the trailing vortex phenomenon and provided valuable information to pilots, air traffic controllers and operators by highlighting the dangers threateninq aircraft from this cause. Accordingly, the Conference passed the following Recommendation RECOMMENDATION 114 - CIRCULATION OF INFORMATION ON TURBULENT WAKE That steps be taken to ensure that appropriate material on turbulent wake, consisting of circulars, and possibly films, etc. is made avail- able to States for circulation to air traffic controllers, operators and pilots. The above Recommendation was approved by the Air Navigation Commission and as a result, certain States were reauested to supply for reproduction in an ICAO Circular, appropriate literature on the subject of turbulent wake. In response to this request, the material in this circular has been supplied by the Governments of Canada, the United Kingdom and the United States of America, whose permission to reprint it is hereby acknowledged. The United States Government's Federal Aviation Agency has also authorized ICAO to reprint, for distribution to States, its film entitled "Wake Turbulence". This film was shown to the Fifth Air Navigation Conference, and is referred to in the Report of that Conference as "an excellent production." Copies of the film are available from ICAO, Montreal, price U.S. 70.00.