Collision prevention systems of aircraft

Claim 1

COLLISION PREVENTION APPARATUS FOR AIRCRAFT INCLUDING AN INTERROGATOR TRANSMITTER AND RECEIVER IN A FIRST AIRCRAFT; A RESPONDER RECEIVER AND TRANSMITTER IN A SECOND AIRCRAFT; MEANS IN SAID FIRST AIRCRAFT TO GENERATE AN INTERROGATION SIGNAL; MEANS IN SAID SECOND AIRCRAFT TO GENERATE A RESPONSE SIGNAL; MEANS TO CODE SUCH RESPONSE SIGNAL WITH THE HEIGHT, COURSE AND SPEED OF SAID SECOND AIRCRAFT; A COMPUTER TO COMPUTE COLLISION RISKS IN SAID FIRST AIRCRAFT; MEANS TO PASS RECEIVED RESPONSE SIGNALS TO SUCH COMPUTER; AN ATTITUDE SENSITIVE DEVICE IN THE SECOND AIRCRAFT; MEANS OPERATED BY SAID ATTITUDE SENSITIVE DEVICE TO SUPPRESS THAT PART OF THE RESPONSE SIGNAL CODED WITH COURSE AND SPEED WHEN THE SECOND AIRCRAFT IS NOT FLYING STRAIGHT AND LEVEL; MEANS TO MODIFY THE INTERROGATION SIGNAL; A FIRST OUTPUT FROM SAID COMPUTER TO INDICATE THAT NO COLLISION IS LIKELY; A DEVICE IN THE FIRST AIRCRAFT TO DETECT SUPPRESSION OF PART OF THE RESPONSE SIGNAL AND HAVING A SECOND OUTPUT; MEANS PASSING SAID FIRST AND SECOND OUTPUTS TO SAID MEANS TO MODIFY THE INTERROGATION SIGNAL; MEANS IN SAID SECOND AIRCRAFT TO DETECT SUCH MODIFICATION AND TO GIVE A THIRD OUTPUT; A FIRST WARNING DEVICE IN THE SECOND AIRCRAFT TO INSTRUCT THE PILOT TO MAINTAIN THE INSTANT COURSE AND SPEED; A SECOND WARNING DEVICE IN THE SECOND AIRCRAFT TO INSTRUCT THE PILOT TO LEVEL UP; AND MEANS CONTROLLED BY SAID ATTITUDE SENSITIVE DEVICE SELECTIVELY PASSING SAID THIRD OUTPUT TO SAID FIRST AND SECOND WARNING DEVICES.