Method and apparatus for determining aircraft-to-ground distances and descent rates during landing
First Claim
1. A system for determining distance to a landing surface and rate of descent to the landing surface from a fixed wing or rotary wing aircraft comprising:
- a rangefinder comprising;
a transmitter of pulses of electromagnetic radiation;
a receiver that receives radiation pulses transmitted from the transmitter and reflected by the landing surface; and
a timing device for determining a time-of-flight of pulses transmitted by said transmitter and received by said receiver where the time-of-flight is less than approximately 200 nanoseconds;
means for determining the distance to said surface from time-of-flight information;
means for determining the rate of descent from time-of-flight measurement of successive pulses and a time interval between said pulses; and
means for displaying the results of the distance measurement and rate of descent information to the operator of the aircraft.
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Abstract
A method and apparatus are described for the determination of the height above a landing surface and the rate of descent to the landing surface for a fixed wing or rotary wing aircraft when the aircraft is less than about 100 feet above the landing surface. The invention relies on the time-of-flight measurement of preferably short infrared pulses that are transmitted from the sensing device and reflected back to the sensing device from the landing surface. Multiple sensors can be used for redundancy. For each sensing unit the distance is determined by a conversion of the time-of-flight information into a distance reading. The rate of descent is determined from successive distance determinations. An additional algorithm determines if the rate of descent is excessive for the distance above the landing surface and generates an alarm such as an audible or visual signal.
40 Citations
9 Claims
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1. A system for determining distance to a landing surface and rate of descent to the landing surface from a fixed wing or rotary wing aircraft comprising:
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a rangefinder comprising; a transmitter of pulses of electromagnetic radiation; a receiver that receives radiation pulses transmitted from the transmitter and reflected by the landing surface; and a timing device for determining a time-of-flight of pulses transmitted by said transmitter and received by said receiver where the time-of-flight is less than approximately 200 nanoseconds; means for determining the distance to said surface from time-of-flight information; means for determining the rate of descent from time-of-flight measurement of successive pulses and a time interval between said pulses; and means for displaying the results of the distance measurement and rate of descent information to the operator of the aircraft. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for determining distance to a landing surface and rate of descent to the landing surface from a fixed wing or rotary wing aircraft comprising the steps of:
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transmitting from the aircraft pulses of electromagnetic radiation; receiving said pulses at the aircraft after they are reflected from said landing surface; determining the time-of-flight of pulses transmitted by said transmitter and received by said receiver where the time-of-flight is less than approximately 200 nanoseconds; determining the distance to said landing surface from the time-of-flight information; determining the rate of descent to said surface from time-of-flight measurement of successive pulses and a time interval between said pulses; and displaying to a pilot of the aircraft a measure of the distance to the landing surface and the rate of descent to the landing surface. - View Dependent Claims (8, 9)
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Specification