The necessity for all weather operations
1969-04-01 00:00:00
Aircraft Engineering TH E MONTHLY JOURNAL OF AERONAUTICAL ENGINEERING RECENT address by Mr O. B. St. John, Superintendent of the path of approaching aircraft and from obstacles on the ground. It is R.A.E. Blind Landing Experimental Unit, Bedford, emphasised expected that the larger transport aircraft expected in service within the the necessity for the introduction of all weather landing techniques next year may make this problem more acute. The mixing of an inertial in the near future. A related problem was the need to improve the pre input into the flight control system holds out the promise of making it cision of air traffic control during the approach phase while also making much less sensitive to interference degrading the ILS beam. the approach path itself more flexible. A later experiment will be made to investigate improved speed-control Mr St. John commented that any research organisation must by laws. Although current autothrottle systems have good speed-holding definition be forward looking, but it also must differentiate between capabilities there is a certain amount of undesirable throttle activity in optimistic speculation on one hand and the need for a firm objective on turbulent conditions which is somewhat disconcerting to both the pas the other. For a future programme to be viable, it had to be based on sengers and the crew. a combination of improving that which already existed, the minimisation of known limitations and the ability to find solutions to foreseeable new Another area to be explored by BLEU is that of greater runway utilisa problems. These three ingredients were all apparent in the BLEU control tion. The existing Instrument Landing System employs a straight-in research programme. approach at the comparatively shallow angle of 3 deg. which imposes a restriction that is not entirely necessary, although it is at present Even today, a modern aircraft represents such a large capital investment dictated by international agreements. The removal of this limitation that it is unacceptable that its operation should be so seriously affected by throws open a whole new area of development work in which the control weather. With the predicted increase in traffic and the high capacity techniques already in use for automatic landing are to be examined for aircraft that will soon be coming into service, some solution must be possible application in the context of air traffic control in the hope of found to eliminate the cost, chaos and confusion that arise to scheduled achieving more accurate and flexible control throughout the whole traffic out of cancellations and diversions. All weather operations are terminal movement area. The derivation and use of accurately controlled inevitable and the approach and landing phase holds the key to the curved flight paths in azimuth would make it possible to achieve greater problem. runway utilisation by bringing aircraft of differing approach speeds along different paths so as to arrive at the runway threshold at equally The U.K. objective is based on using automatic landing to proceed spaced intervals. The increased accuracy could also allow a reduction in steadily towards near blind operations. Both B.E.A. Tridents and parallel runway separation at particular airports if all the aircraft were B.O.A.C. VC10s have been making automatic landings in good visibility suitably equipped, and would dramatically increase the total possible on their scheduled services to build up experience of the flight control movements per hour at the airport. The use of steeper initial approach systems they use. The two vital considerations in all weather operations paths in the vertical plane is another possible method of alleviating the are regularity and safety, and these must be demonstrated to the satis noise abatement problem which is bound to be of even greater importance faction of the ARB before the automatic landing systems are used in in the future. the weather for which they were designed. The safety target set by the ARB is one in ten million, a higher level than yet attained. Yet im The need for improved reliability is the counterpart to BLEU's control proved regularity cannot be exploited unless an extremely high standard research programme which is mainly concerned with achieving better of safety can be guaranteed, and this in turn demands both good per performance. The improved reliability is likely to be largely the respon formance and high reliability to ensure that accidents do not occur. sibility of the equipment manufacturer and its attainment of great im portance to the aircraft manufacturer and the airline operators. As the The present control research being undertaken by BLEU is centred automatic system becomes more and more reliable, it will become possible around the Comet 3B which is specially equipped for this work. The to reduce the quantity of fuel carried in case the contingency arises where heart of the installation is an Electronics Associates Inc. TR48 analogue a diversion from the intended destination is necessary at the end of the computer which is incorporated into a standard autopilot and by using a flight. The ultimate will be when the overall reliability becomes sufficiently variety of new sensors, including an inertial platform, a wide range of high for it to be unnecessary to cater for a diversion at all. However, automatic control laws can be investigated. The analogue computer in there might be reasons unconnected with the automatic landing system, the Comet 3B has been specially strengthened for experimental use in the such as a blocked runway or other forms of force majeure, that would air which is not the normal environment for a computer of this type. make it difficult to extend the benefit to such an extent. In the particular A second TR48 computer facility is available in the laboratory in order case of a blocked runway, it might be possible to make use of a parallel that the flight experiments can be simulated on the ground. In this way runway as a last minute alternative so that a landing could still be made. a direct comparison can be made between the simulated model and the actual trials. The great advantage of this type of computer is that the As an indication of the benefit of such a trend towards an increase in control laws can be altered between flights, whereas hitherto it took a reliability, the payload of the Concorde supersonic airliner is estimated couple of months or so to insert a different programme into the system. to be about 6 per cent of the all-up weight of the aircraft, whereas the The initial experiments now in progress are concerned with the im excess fuel carried to allow for a diversion to an alternate airfield is likely provement of existing control laws that are being used for the approach to be in excess of 10 per cent. Even a minor reduction in the percentage of fuel carried for diversion would be a most attractive proposition from and landing phase. At the present time a system is being studied which the economic point of view, but the need to maintain adequate reliability mixes inertial terms with the main guidance signals which are derived and hence safety will present a considerable challenge to the equipment from the Instrument Landing System. The ILS is susceptible to inter manufacturer. ference, in particular that arising from other aircraft taking off in the
http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.pngAircraft Engineering and Aerospace TechnologyEmerald Publishinghttp://www.deepdyve.com/lp/emerald-publishing/the-necessity-for-all-weather-operations-0fHjuYsNg3
Aircraft Engineering TH E MONTHLY JOURNAL OF AERONAUTICAL ENGINEERING RECENT address by Mr O. B. St. John, Superintendent of the path of approaching aircraft and from obstacles on the ground. It is R.A.E. Blind Landing Experimental Unit, Bedford, emphasised expected that the larger transport aircraft expected in service within the the necessity for the introduction of all weather landing techniques next year may make this problem more acute. The mixing of an inertial in the near future. A related problem was the need to improve the pre input into the flight control system holds out the promise of making it cision of air traffic control during the approach phase while also making much less sensitive to interference degrading the ILS beam. the approach path itself more flexible. A later experiment will be made to investigate improved speed-control Mr St. John commented that any research organisation must by laws. Although current autothrottle systems have good speed-holding definition be forward looking, but it also must differentiate between capabilities there is a certain amount of undesirable throttle activity in optimistic speculation on one hand and the need for a firm objective on turbulent conditions which is somewhat disconcerting to both the pas the other. For a future programme to be viable, it had to be based on sengers and the crew. a combination of improving that which already existed, the minimisation of known limitations and the ability to find solutions to foreseeable new Another area to be explored by BLEU is that of greater runway utilisa problems. These three ingredients were all apparent in the BLEU control tion. The existing Instrument Landing System employs a straight-in research programme. approach at the comparatively shallow angle of 3 deg. which imposes a restriction that is not entirely necessary, although it is at present Even today, a modern aircraft represents such a large capital investment dictated by international agreements. The removal of this limitation that it is unacceptable that its operation should be so seriously affected by throws open a whole new area of development work in which the control weather. With the predicted increase in traffic and the high capacity techniques already in use for automatic landing are to be examined for aircraft that will soon be coming into service, some solution must be possible application in the context of air traffic control in the hope of found to eliminate the cost, chaos and confusion that arise to scheduled achieving more accurate and flexible control throughout the whole traffic out of cancellations and diversions. All weather operations are terminal movement area. The derivation and use of accurately controlled inevitable and the approach and landing phase holds the key to the curved flight paths in azimuth would make it possible to achieve greater problem. runway utilisation by bringing aircraft of differing approach speeds along different paths so as to arrive at the runway threshold at equally The U.K. objective is based on using automatic landing to proceed spaced intervals. The increased accuracy could also allow a reduction in steadily towards near blind operations. Both B.E.A. Tridents and parallel runway separation at particular airports if all the aircraft were B.O.A.C. VC10s have been making automatic landings in good visibility suitably equipped, and would dramatically increase the total possible on their scheduled services to build up experience of the flight control movements per hour at the airport. The use of steeper initial approach systems they use. The two vital considerations in all weather operations paths in the vertical plane is another possible method of alleviating the are regularity and safety, and these must be demonstrated to the satis noise abatement problem which is bound to be of even greater importance faction of the ARB before the automatic landing systems are used in in the future. the weather for which they were designed. The safety target set by the ARB is one in ten million, a higher level than yet attained. Yet im The need for improved reliability is the counterpart to BLEU's control proved regularity cannot be exploited unless an extremely high standard research programme which is mainly concerned with achieving better of safety can be guaranteed, and this in turn demands both good per performance. The improved reliability is likely to be largely the respon formance and high reliability to ensure that accidents do not occur. sibility of the equipment manufacturer and its attainment of great im portance to the aircraft manufacturer and the airline operators. As the The present control research being undertaken by BLEU is centred automatic system becomes more and more reliable, it will become possible around the Comet 3B which is specially equipped for this work. The to reduce the quantity of fuel carried in case the contingency arises where heart of the installation is an Electronics Associates Inc. TR48 analogue a diversion from the intended destination is necessary at the end of the computer which is incorporated into a standard autopilot and by using a flight. The ultimate will be when the overall reliability becomes sufficiently variety of new sensors, including an inertial platform, a wide range of high for it to be unnecessary to cater for a diversion at all. However, automatic control laws can be investigated. The analogue computer in there might be reasons unconnected with the automatic landing system, the Comet 3B has been specially strengthened for experimental use in the such as a blocked runway or other forms of force majeure, that would air which is not the normal environment for a computer of this type. make it difficult to extend the benefit to such an extent. In the particular A second TR48 computer facility is available in the laboratory in order case of a blocked runway, it might be possible to make use of a parallel that the flight experiments can be simulated on the ground. In this way runway as a last minute alternative so that a landing could still be made. a direct comparison can be made between the simulated model and the actual trials. The great advantage of this type of computer is that the As an indication of the benefit of such a trend towards an increase in control laws can be altered between flights, whereas hitherto it took a reliability, the payload of the Concorde supersonic airliner is estimated couple of months or so to insert a different programme into the system. to be about 6 per cent of the all-up weight of the aircraft, whereas the The initial experiments now in progress are concerned with the im excess fuel carried to allow for a diversion to an alternate airfield is likely provement of existing control laws that are being used for the approach to be in excess of 10 per cent. Even a minor reduction in the percentage of fuel carried for diversion would be a most attractive proposition from and landing phase. At the present time a system is being studied which the economic point of view, but the need to maintain adequate reliability mixes inertial terms with the main guidance signals which are derived and hence safety will present a considerable challenge to the equipment from the Instrument Landing System. The ILS is susceptible to inter manufacturer. ference, in particular that arising from other aircraft taking off in the
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Aircraft Engineering and Aerospace Technology
– Emerald Publishing
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