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Aviation History
1963
1963 - 1840.PDF
FLIGHT International, 17 October 1963 647 the last-named mode to be initiated by pressing the autopilot disconnect button. It was claimed that height losses after applica tion of thrust can be kept as small as 8ft when using a SCAT- directed technique. This figure is significantly less than those suggested by other speakers, and could have a vital part to play in critical height minima. Another area where TWA differs from other airlines is that it has no intention at present of using radio altimeters, except for a single installation with which it is hoped to establish the adequate accuracy of barometric altimeters. Thus the equipment programme of TWA is limited to the improvement of autopilot capability and reliability, provision of autothrust using SCAT, and the display of SCAT information for "go-around." With this equipment TWA anticipates being able to operate with increased safety to Phase II weather minima. The FAA gave an account of its experiences with the BLEU DC-7, which had made 1,149 automatic landings at 47 airfields. During 500 of these approaches the autopilot was still coupled to the ILS glide-slope at a wheel height of 74ft. Virtually no problems were encountered during the programme. Four occasions when a sequence-switch failure caused a missed approach were traced to a switch contact improperly mounted after maintenance. For evaluation purposes, a US-manufactured radio altimeter has replaced the original S.T.C. unit, but pilots had expressed a preference for the presentation features of the British device. The next phase of the FAA DC-7 programme is to explore flight director landings under instrument conditions. A Collins FD-108 Integrated Flight System has been installed, together with a pointer and drum a.s.i., an angle of attack indicator and a Bendix Eclipse Pioneer vertical-tape presentation of signals from radio altimeter, v.s.i. and altimeter. This new FAA programme will supplement information from USAF trials at Randolph Field. The IFALPA viewpoint was put forward by Capt R. C. Gerber of ALPA. Stated requirements for ground equipment were similar to those enumerated by previous speakers, but the importance of a 100ft height-marker beacon, narrow-gauge touch-down zone light ing, runway centre-line and turn-off lighting, slant range visibility indication and the provision of compacted under-run, over-run and hard shoulders for runways were particularly emphasized. Airborne equipment specified included dual ILS receivers, improved warning flag displays, radio altimeters, instantaneous vertical speed indicat ors, windshield rain removal equipment, duplicated flight directors, DME for use during ILS approach, speed-command and angle of attack system for flight director or auto-throttle use and, finally, larger (Sin) flight instrument displays. Capt Gerber called for instrument displays adequate for manual blind landings when required, and stressed the importance of good manual-flight handling characteristics for "go-arounds" and manual reversion. Pilots expected an orderly and planned progress towards lower minima, with each step being carefully worked up through the "de-bugging" period. They were interested in the various forms of stick-steering, control-wheel steering and force- steering and believed that pilot reaction to such systems had so far been favourable. A plea was made for a single internationally agreed standard for approach lighting installations, standardizing either the ALPA or Calvert system with suitable additions. It was also felt that improved pilot training, and training equipment was required for instrument-to-visual and automatic-to-manual transi tions, both for the continued approach and for the "go-around" manoeuvres. Simulators and reduced-visibility screens in aircraft were regarded as promising devices in this programme. During the panel discussion mention was made of the high success rate in manual blind landings in a current R&D programme at San Antonio, using T-39s fitted with a flare computer in the flight director system. This has been done with a glide-slope or flight path angle computed from TAS and vertical velocity. The value of the fog simulator chamber at Areata in establishing the optimum lighting patterns for RVRs of 700ft was agreed, and this particular research tool is likely to be kept busy for some time. Some 254 transmissometers are already installed in the USA and it is likely that every instrument runway will be equipped with at least two. An impartial observer at the meeting might have been struck by the variety of solutions proposed for the same problem. Particular examples are the PanAm and UAL decision to retain manual control in the pitch axis, while BAC and the two British airline corporations propose to do the opposite and automate this channel first of all. TWA are almost certainly alone in their proposed continued use of barometric altimeters. Widespread use of angle of attack, both "raw" and processed, by the American manufacturers and operators, seemed to leave the British delegates quite unimpressed, as did the use and instrument display of instantaneous vertical velocity, although the limitations of plain barometric rate are generally agreed. The FAA evidently do not at present accept the "official" British view that manual blind landings are not worth pursuing. An impressive FAA/USAF research and development programme is under way to examine this possibility. The same applies to the primary guidance system for all-weather operations. The UK is apparently sticking with ILS, while the US is looking for second- generation systems. Some US airlines appear to be particularly aware of the limita tions of previous flight director instruments, and the new Collins "3-D" FD-108 system appears to be "front runner" among the possible replacements. Five-inch diameter versions are available. A real attempt is being made with this instrument to put all the important parameters on display in the one dial, including attitude, director, radio displacement, yaw and, in some versions, speed- command, DME, radio altitude and command altitude. The role of the pilot receives different emphasis in the US and Britain. US airlines appear to be very reluctant to abandon the acquired skills of the pilot, and a much greater effort to make continued use of them is apparent in the many ideas and products of the US industry. If this difference of opinion and intention is as real as it appears, there is a real possibility that quite different solutions will be found in the two major aviation countries. The eventual occupants of the first civil aircraft to operate in low minima will know that all practical solutions have been examined. L.A. Some FAA and Industry Research Projects f^OMPUTERS and simulators of a number of types are being ^* used by the FAA at its National Aviation Facilities Experi mental Centre (NAFEC) at Atlantic City for elaborate research Projects connected with flight control, operational equipment and traffic control problems. An impressive amount of laboratory msirurnentation has been installed at NAFEC to ensure accuracy and uniformity of measurement in terms of national standards. There are a primary measurement standards laboratory, photo- muric laboratory, navigation aids and flight control laboratory and an environmental laboratory. An IBM 7090 computer is used to process digital magnetic tape wh'ch has been converted from analogue tapes extracted from au+jorne recording systems. The ratio of time required for measur-m 6 data to that required for reducing it has been cut down from Some of the 60 single-track target generators and "pilots" in the FAA "io <e/ B ATC simulator at Atlantic City
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