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Aviation History
1961
1961 - 0259.PDF
PLIGHT, 24 February 1961 263 77,, hypothetical rearrangement of the Southampton Control Zone shri/s how many square miles of airspace might be liberated for use ty mate pilots. The control and transition zones are controlled space in a!l weathers, but there is free space underneath the transition zone; fret lanes through the control zone are indicated on the aeronautical chert. Information given includes maximum height of the lane, and the frequency on which the airfield approach is called to obtain entry clearance. Both free lanes follow line features on the ground this airspace extends upwards from ground level and in IMC isout-of-bounds to all but fully equipped operators. The big London and Manchester Control Zones and all airways are IFR-only allthe time, and special clearance must be obtained before light aircraft can enter or cross them. Radical redesign by the FAA of US airspace poses questions asto whether we are making the best use of our own: whether we should cease to think in terms of VFR and IFR conflicts andembark upon a fairer apportionment of the air above us in terms of an equable partnership. The present system of free lanes toaerodromes in control zones is far from satisfactory; too much reliance is placed upon accurate track-keeping by scanty visualreference. The free lane through the London Control Zone into Fair Oaksis a case in point. Before the zone was extended southwards a few miles in the tidying-up process, track guidance from the southwas provided by the railway line from Guildford to Woking, whence it was about one minute's flying on the same track tothe centre of the airfield. To keep Fair Oaks traffic clear of Wisley traffic, the free lane was then swept westwards to a terminal pointat a cemetery that is not, of course, shown on the half-million map. There is no line feature to follow between cemetery and aerodromeand no radio or D/F with which position can be checked. Flying has been made more, rather than less, difficult—and, it might beargued, not quite so safe. Another unsatisfactory feature of free-lane entry into controlzones is th3t flight planning is complicated by lack of ready infor- mation. Free lanes are not shown on any map, and a long-distancetelephone call is usually necessary to check the position of the lane. If it were a simple matter to reduce the size of control zones,many of these free-lane problems would disappear. The design case is apparently that of a fully loaded Constellation or DC-6Bclimbing out through the zone with a 3Okt tailwind on a hot day. Rate-of-climb may then, apparently, be only 200ft/min, so thatfor the aircraft to reach 1,500ft before it leaves the zone the latter must have a diameter of at least 24 miles. Add another 500ft forseparation and some for luck, and the size of the zone assumes giant proportions. It would not, of course, be practical to specify a control zonewith a shelving floor, but it may very well be worth while having control over two levels; one, the small control zone proper, andthe other the "transition zone" principle adopted by the FAA and the French Ministry of Transport. More private pilotswould agree that the extra complication of maps and charts would be worthwhile if it gave free entry at low level to aerodromes nowwithin the confines of control zones. What has been done in France (for an experimental period of six months) is to establish a series of zones around Orly andLe Bourget airports. The inner one, according to the magazine Les Ailes, extends from ground level to flight level 30 (3,000fton l,I03mb) and is restricted to aircraft with radio arriving at or departing from Le Bourget, Orly, Villacoublay or Bretigny.Prior authorization is required from Paris control or from the tower of one of the airfields. The private fields of Chelles, Mitry-Mory and Enghien Moisselles have permanent authorization from Le Bourget to fly subject to certain conditions. La Ferte Alaiswill during weekdays have similar permanent authorization from Paris control and Bretigny; at weekends it is free because the zoneis contracted while Bretigny is not active. Around the central area is established an "upper reserved ter-minal area" extending to flight level 65. Lower levels are respec- tively 3,000ft at 24 miles, 2,500ft at 18 miles, and 1,300ft abovemean sea level over an irregular area bounded by the arcs of 16-, 15- and 11-mile-radius circles based on Bourget and Orly (seemap). In this area positive control is exercised, and all aircraft must have two-way radio.Below the upper area is the "lower reserved terminal area" extending from ground level to the lower limits of the upperreservation. Within this airspace airliners on IFR flight plans are prohibited—the area is completely reserved for light aircraft. Pre-sumably if a transport climbing out from either of the main Paris airports cannot make 1,300ft by the time that it is 18-25kmfrom the runway, it must either be cleared through some other climb-out path, or take off at a lower weight. On the score ofnoise alone it seems undesirable for climb rates of only 200ft/min to be tolerated, and quite unreasonable that such poor perform-ance should be allowed to impose such harsh restrictions on other users of the airspace.Conclusions to be drawn from the foregoing seem obvious: if ir is possible to modify zoning of the airspace in the United Statesand in France, it must surely also be possible here. The line of attack seems to be to adopt the transition zone, beneath whichthe airspace is free, and to reduce the size of control zones to more sensible proportions. Once this is done, special cases canall be considered, and zones and areas adjusted where, for example, special climb and descent path are required. Revisionof the size and shape of control zones and control areas over the British Isles is long overdue. Such a good reason for changeshould surely not be ignored. A. T. P. SENSING TOTAL TEMPERATURE A CCURATE measurement of total temperature (i.e., ambient**• temperature as raised by kinetic heating) involves a number of problems, but now available from a British source is a sensingunit designed to give precise results over a temperature range of -100cC to +35O°C. Known as the Total Temperature ProbeType 102, it is being manufactured under licence by Research & Engineering Controls Ltd, of 9 Old Bridge Street, Kingston-on-Thames, Surrey (Kingston 6288), an associate company of the Rosemount Engineering Co ofMinneapolis, USA. The probe is stated to give fastand accurate measurement even when de-icing heat is applied, andto withstand extreme effects of vibration and shock. Special"open wire" elements for flight- test use have a time-constant of0.02sec and a recovery error of less than 0.1 per cent of absolutetemperature. The de-iced probes should have particularly usefulapplication in civil and military aircraft under operational condi-tiors, where they can provide ft>< Type 102 temperature-sensing probe ishc-wn approximately one-fourth actual size) information to assist in the selection of optimum engine settingsfor economy and safety. They can also help in the determination of true airspeed and in locating high-altitude jetstreams. The probecan, of course, be used either as a component of an air-data com- puter system or for a direct-reading temperature indicator; and, onthe ground, it is of use in wind-tunnel instrumentation, particularly for research into icing. The Rosemount Company's probes are in use by airline opera-tors and aircraft manufacturers, including Air France (for Boeing 707s), TCA (who have specified them for any future types theymay operate), and Boeing, who, it is stated, will henceforth employ the equipment in all 707 variants. Research & Engineering Controls, who have fulfilled a numberof dollar-earning development and production orders for Rose- mount, hold a licence to manufacture all the American company'sproducts and to sell them in European markets. Apart from tem- perature probes, these products include compensated pitot/statictubes for aircraft flying at speeds of up to Mach 3; pressure trans- ducers and altimeters: platinum resistor immersion probes fortemperatures ranging from that of liquid helium to +l,500°F; and multi-point temperature monitoring and control equipment.The American company is directed by Dr F. D. Werner, and the managing director of Research & Engineering Controls Ltdis Mr B. Rogal, BSc(Eng), AMIEE (until recently chief development engineer of Wayne Kerr Laboratories), with Mr R. W. Sutton(the well-known aeronautical consultant) and Mr J. G. Gallagher as fellow board-members.
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