Automatic control systems

Claim 1

AN AUTOMATIC PITCH CONTROL CHANNEL FOR AN AUTOMATIC FLIGHT CONTROL SYSTEM OF AN AIRCRAFT, SAID CONTROL CHANNEL COMPRISING MORE THAN TWO-SUBCHANNELS FOR ACTUATING CONCURRENTLY WITH ONE ANOTHER PITCH CONTROL SURFACE MEANS OF THE AIRCRAFT, EACH SAID SUB-CHANNEL INDIVIDUALLY COMPRISING SIGNAL SOURCE MEANS FOR PROVIDING SIGNALS IN ACCORDANCE WITH AT LEAST HEIGHT AND PITCH MANOEUVERS OF THE AIRCRAFT; PITCH COMPUTER MEANS RESPONSIVE TO SIGNALS PROVIDED BY SAID SIGNAL SOURCE MEANS TO PROVIDE A PITCH DEMAND SIGNAL, SAID COMPUTER MEANS INCLUDING MEANS SELECTIVELY SWITCHABLE TO ANY ONE OF A PLURALITY OF DIFFERENT OPERATIONAL MODES APPROPRIATE RESPECTIVELY TO DIFFERENT SUCCESSIVE PHASES OF A LANDING MANOEUVRE; A SERVO SYSTEM FOR ACTUATING SAID PITCH CONTROL SURFACE MEANS IN ACCORDANCE WITH THE PITCH DEMAND SIGNAL PROVIDED BY SAID PITCH COMPUTER MEANS; REFERENCE SIGNAL MEANS FOR PROVIDING SIGNALS DEFINING A PLURALITY OF DIFFERENT DATUM VALUES RELATED RESPECTIVELY TO DIFFERENT AIRCRAFT HEIGHTS AT WHICH DIFFERENT SUCCESSIVE PHASES OF SAID LANDING MANOEUVRE SHOULD BE COMMENCED, SAID REFERENCE SIGNAL MEANS BEING COUPLED TO SAID PITCH COMPUTER MEANS TO DEFINE DURING EACH SAID PHASE THE DATUM VALUE OF HEIGHT APPROPRIATE TO COMMENCEMENT OF THE NEXT SUCCESSIVE PHASE; SIGNAL DRISCRIMATING MEANS COUPLED TO THE REFERENCE SIGNAL MEANS AND TO SAID SIGNAL SOURCE MEANS TO PROVIDE A SWITCHING SIGNAL WHEN THE AIRCRAFT HEIGHT IS SUBSTANTIALLY EQUAL TO THE DATUM VALUE OF HEIGHT THEN BEING DEFINED BY SAID REFERENCE SIGNAL MEANS; AND SWITCHING MEANS FOR SWITCHING SAID PITCH COMPUTER MEANS TO THE OPERATIONAL MODE APPROPRIATE TO SAID NEXT SUCCESSIVE PHASE OF SAID LANDING MANOEUVRE IN RESPONSE TO THE CONDITION IN WHICH THE SIGNAL DISCRIMINATING MEANS OF A MAJORITY OF SAID SUB-CHANNELS EMIT SAID SWITCHING SIGNAL.