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The Admiralty Tide Tables give the utmost accuracy in tidal calculations, but at the cost of a number of tedious interpolations. Many seamen, particularly those in small vessels, would be willing to sacrifice some of this accuracy if they could have a simpler form of calculation. In any case meteorological effects, and the uncertainty of the time and height corrections for some of die smaller ports impose uncertainties which upset the apparent accuracy. In fact many yachtsmen do not use the Admiralty Tide Tables, but use tables in commercial almanacs, usually giving the times and heights of high water only.

An informal discussion on the operation of light aircraft took place at a meeting of the Technical Committee of the Institute in London on 21 April 1976. A personal view expressed by Mr. F. S. Stringer and comments by Mr. C. Powell and Professor A. N. Black are printed below.Recent technical press disclosures have highlighted C.A.A. concern that the London Air Traffic Zone is being entered by unauthorized light aircraft, the infringements varying from minor boundary incursions to major crossings of the area. The pilots involved vary in experience, and in most if not all cases have been flying under VFR rules and out of radio contact with Air Traffic Control. It seems very probable that these pilots are lost, or at least very unsure of their position; the topographical relation of charts to places on the ground is becoming increasingly difficult to interpret due to the complexity of built-up areas, especially around the T.M.A.s. Not all aircraft carry VOR or ADF and the map and DR are the main navigational aids; some pilots are reluctant to call for radar assistance for a variety of reasons.

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