Blind landing aids

Claim 2

A blind landing aid system for visualizing, on board an aircraft the landing runway said aircraft is approaching, said system comprising: transmitting means on board said aircraft for emitting an infra-red beam scanning the ground in front of said aircraft in accordance with a predetermined pattern; responder beacons bounding said runway for transmitting respective radioelectric pulses upon being swept by said infra-red beam; and receiving means on board said aircraft comprising a cathode ray tube having a screen and means for scanning said screen in synchronism with the scanning performed by said infra-red beam for receiving said pulses and for visualizing said beacons as luminous spots on said screen.

Claim 3

A transmitting-receiving apparatus, for use in a system as claimed in claim 1, comprising: an infra-red source for emitting an infra-red beam; scanning means for the ground to be scanned by said beam, in front of said aircraft, in accordance with a predetermined pattern; a radioelectric receiver for receiving the radio-electric pulses from said beacons; a cathode-ray tube having a control electrode, connected to said receiver, and deflection means; and synchronizing means, coupled to said scanning means and to said deflection means for synchronizing the scanning of the screen of said cathode-ray tube and the scanning of the ground by said infra-red beam.

Claim 4

A transmitting-receiving apparatus, for use in a blind landing aid system capable of visualizing, on board an aircraft the landing runaway said aircraft is approaching, said apparatus comprising: an infra-red source for emitting an infra-red beam: scanning means for the ground to be scanned by said beam, in front of said aircraft, in accordance with a predetermined pattern; a radioelectric receiver for receiving the radio-electric pulses from beacons bounding said runway; a cathode-ray tube having a control Electrode, connected to said receiver, and deflection means; and synchronizing means, coupled to said scanning means and to said deflection means for synchronizing the scanning of the screen of said cathode-ray tube and the scanning of the ground by said infra-red beam,; said scanning means comprising a first rotating prism having mirror facets and located for deviating said beam by a mean angle substantially equal to 90*; means for rotating said prism at a predetermined speed; a plane mirror located at an angle of substantially 45* from the mean direction of the beam reflected by said prism; means for mounting said plane mirror rotatably about an axis located in the plane of incidence of said infra-red beam on said prism; and oscillating means coupled to said plane mirror for oscillating said plane mirror about said axis.

Claim 5

A transmitting-receiving apparatus, for use in a blind landing aid system capable of visualizing, on board an aircraft the landing runaway said aircraft is approaching, said apparatus comprising: an infra-red source for emitting an infra-red beam: scanning means for the ground to be scanned by said beam, in front of said aircraft, in accordance with a predetermined pattern; a radioelectric receiver for receiving the radio-electric pulses from beacons bounding said runway; a cathode-ray tube having a control Electrode, connected to said receiver, and deflection means; and synchronizing means, coupled to said scanning means and to said deflection means for synchronizing the scanning of the screen of said cathode-ray tube and the scanning of the ground by said infra-red beam,; said scanning means comprising a first rotating prism having mirror facets and located for deviating said beam by a mean angle substantially equal to 90*; means for rotating said prism at a predetermined speed; a plane mirror located at an angle of substantially 45* from the mean direction of the beam reflected by said prism; means for mounting said plane mirror rotatably about an axis located in the plane of incidence of said infra-red beam on said prism; and oscillating means coupled to said plane mirror for oscillating said plane mirror about said axis.

Claim 6

An apparatus as claimed in claim 3, wherein said synchronizing means comprise an auxiliary light source for emitting a light beam towards said prism; and a photodetector located for detecting said light beam after reflection on said prism.

Claim 7

A responder beacon, for use in a system as claimed in claim 1, comprising: an infra-red detector; optical means for focusing any received infra-red beam substantially on said detector; and a radioelectric transmitter coupled to said detector for generating a radioelectric pulse of predetermined frequency upon said detector being swept by an infra-red beam.