HL Deb 10 March 1948 vol 154 cc618-20

My Lords, I beg to ask His Majesty's Government the question standing in my name on the Order Paper.

[The question was as follows:

To ask His Majesty's Government whether orders have been issued modifying the use of the G.C.A. system; what is the nature of the orders and the reason for them.]


My Lords, when the first British civil G.C.A. (Ground Controlled Approach) equipment was installed at London Airport on July 1, 1947, the aim was to give it a period of trial before attempting to define with any degree of precision its future rôle in the air traffic control scheme. It was to be regarded as an emergency landing aid and a monitoring equipment, rather than as I standard runway approach aid—of which three types were already available at London Airport—S.C.S. (Signal Corps System) 51, S.B.A. (Standard Beam Approach) and B.A.B.S. (Beam Approach Beacon System). S.C.S. 51 is the forerunner of the future I.C.A.O. approved runway approach system, known as I.L.S. (Instrument Landing System). The efficiency of the G.C.A. crew, and the growing predilection of numbers of operators for the use of G.C.A. in preference to other approach aids, led to a greater use of G.C.A. than had at first been anticipated. A tendency to place a degree of reliance upon this aid beyond its capacity was becoming apparent.

Meanwhile, a careful technical assessment of the accuracy of G.C.A. controlled runway approaches was proceeding. This involved detailed analysis of large numbers of approaches, and therefore required time. The conclusion was reached that technical considerations make it unwise to rely on G.C.A. approaches when weather conditions are such that a visual approach and landing cannot be made from a position of 800 yards from the touch-down point at a height of 150 feet. An order to this effect was issued to divisional and airport authorities on March 3, and to operators on March 4. A notice to airmen amplifying these instructions was issued on March 9. Where installed G.C.A. is of course always available to aircraft in an emergency.


My Lords, while thanking the noble Lord for his answer, may I say that I, no doubt like many others of your Lordships, am an occasional passenger in civil aircraft, and therefore no one could be keener than I on questions of safety. But does not this decision seem rather a panicky one? It arises, I imagine, out of the latest disaster at London Airport. I would like to ask whether it is not a fact that over a thousand landings have taken place with the use of the G.C.A. system without accident or incident? Presumably there will be an inquiry into the last disaster. Would it not be as well to await the result of that inquiry before issuing an order which may rather seriously cramp the use of the system?


My Lords, I share with the noble Earl great confidence in the G.C.A. system. Until recently, the weather conditions since it was brought into use at London Airport last summer had been such that there had not been much experience with it in really foggy conditions. The circumstances in which the Sabena accident occurred at the beginning of the month, brought home the desirability of issuing an immediate order regarding G.C.A., rather than awaiting the issue of a notice to airmen which was in course of preparation. As to the noble Earl's further point, regarding possible undue restriction of the use of the system, he may be interested to know that generally the weather minima laid down for G.C.A. by the Civil Aeronautics Administration of the United States are more restrictive than those which we have established.


Can the noble Lord say whether the inquiry which is taking place into the Sabena accident in any way connects up that accident with the use of the G.C.A. system?


It would be premature for me to say anything about that, pending the issue of the report on the inquiry.


Can the noble Lord say whether this is the first time that any weather minima have been laid down by his Ministry in respect of commercial aircraft?


Yes, that is so. The noble Earl will bear in mind, however, that this aid has been used only experimentally, in the first instance, for civil aircraft at London Airport and for a relatively short period. It has been used for only a few months and until recently we have not had any experience of using it in really foggy weather.