Forward looking windshear detection system

• US 4,965,573 A
• Filed: 10/03/1988
• Issued: 10/23/1990
• Est. Priority Date: 10/03/1988
• Status: Expired due to Fees

• Current Assignee: Delco Electronics Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: Delco Electronics Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Gallagher, Brian J., Klein, Peter P., Schaefer, Wayne A.
• Primary Examiner(s): Orsino, Joseph A.
• Assistant Examiner(s): Swarthout, Brent
• Application Number:
  US07/252,732
• Time in Patent Office: 750 Days
• Field of Search: 340/968, 340/963, 340/967, 73/128 T, 73/189, 244/181, 342/26, 342/53, 364/433, 364/427, 364/428, 374/112
• US Class Current: 340/968
• CPC Class Codes: G01P 5/10 by measuring thermal variables

Abstract

An integrated, remote sensing and reactive detection system is provided for detecting and confirming the presence of hazardous microbursts, macrobursts, and windshears in the general flight path of an aircraft. An infrared remote sensing system is used to seek out, detect, and provide advanced alerts of thermal gradients ahead of an aircraft which correlate with windshear conditions. The measurement of atmospheric temperature is accomplished by a scanning, multi-spectral radiometer that sweeps an approximate 60 degrees path in front of the aircraft at about a 5 hertz rate. The radiometer employs two rows of detectors that are slightly offset resulting in two simultaneous measurements of temperature that are about 7 degrees apart in elevation angle. This dual information allows the continuous measurement of the atmospheric vertical temperature gradient, or lapse rate, for use in determining the atmospheric stability, and hence the probability of microburst occurrence as well as the continuous measurement of atmospheric azimuth temperature gradient for use in detecting the existence of a negative gradient that correlates with a microburst.

Claims

1. A method of estimating the range of a microburst ahead of an aircraft comprising the steps of scanning the atmosphere in front of the aircraft over a predetermined azimuth angle, simultaneously detecting infrared radiation at wavelengths λ

₁ and λ

₂ and calculating the range to the microburst in accordance with the following equation ##EQU9## where r_o is the range to the microburst

Δ

W_s1 is the difference between radiation at a first infrared wavelength λ

₁ and at a reference wavelength λ

Δ

W₂ 2 is the difference between radiation at a second infrared wavelength λ

2 and at a reference wavelength λ

T is the ambient temperature

L is the width of the microburst

W_b (λ

_i, T) is the black body radiance at wavelength, λ

_i

σ

_ai is the atmospheric extinction at λ

_i

σ

_ri is the increase in extinction in the microburst due to additional moisture and rain particles.

2. A method of measuring atmospheric lapse rate from an aircraft comprising the steps of scanning a small instantaneous field of view of the atmosphere in front of the aircraft over a predetermined azimuth field of view, detecting infrared radiation simultaneously at two wavelengths and at two elevations separated by a predetermined elevation angle, in order to calculate a vertical radiance gradient of the atmosphere a predetermined distance ahead of the aircraft and computing lapse rate as a function of vertical radiance gradient and atmospheric extinction.

3. A method of advising the crew of an aircraft of atmospheric conditions conducive to windshear comprising the steps of:

a. scanning an instantaneous field of view of the atmosphere in front of the aircraft over a predetermined azimuth angle while simultaneously detecting atmospheric radiance at first and second predetermined distances in front of the aircraft and at first and second elevations separated by a predetermined elevation angle;

b. continuously computing the horizontal and vertical radiance gradient at said first and second distances and determining lapse rate as a function of vertical gradient;

c. computing a severity index as a function of lapse rate and indicating when the index exceeds a predetermined threshold;

d. determining the polarity of the horizontal gradient at said first predetermined distance relative to the gradient of the undisturbed atmosphere at said second predetermined distance;

e. indicating a microburst if the polarity is negative and the horizontal gradient and amplitude of the radiance at said first predetermined distance exceed predetermined thresholds.

4. A method of advising the crew of an aircraft of atmospheric conditions conducive to windshear comprising the steps of:

a. scanning an instantaneous field of view of the atmosphere in front of the aircraft over a predetermined azimuth angle while simultaneously detecting atmospheric radiance at far, near and reference distances in front of the aircraft and at upper and lower elevations separated by a predetermined elevation angle;

b. continuously computing the horizontal and vertical radiance gradient at said far, near and reference distances and determining lapse rate as a function of vertical gradient;

c. computing a severity index as a function of lapse rate and indicating when the index exceed a predetermined threshold;

d. determining the polarity of the horizontal gradient at said far distance relative to the gradient at said reference distance;

e. indicating a microburst if the polarity is negative and the horizontal gradient and amplitude of the radiance at said first predetermined distance exceed predetermined thresholds and

f. indicating a range to the microburst as a function of the difference in infrared absorption at the far and near distances.

5. An airborne forward looking windshear detection system comprising

an infrared sensor means for scanning an instantaneous field of view of the atmosphere in front of the aircraft over a predetermined azimuth angle while simultaneously detecting atmospheric radiance at first and second predetermined distances in front of the aircraft and at first and second elevations separated by a predetermined elevation angle,

said infrared sensor means comprising first and second rows of detector means for measuring the atmospheric radiance at first, second and reference wavelengths respectively,

a computer for processing the atmospheric radiance measured at said first and reference wavelengths to determine whether a negative azimuth gradient exists in the atmosphere,

said computer processing the atmospheric radiance measured at said first and second wavelengths to determine atmospheric the lapse rate.

6. An airborne forward looking windshear detection system comprising

an infrared sensor means for scanning an instantaneous field of view of the atmosphere in front of the aircraft over a predetermined azimuth angle while simultaneously detecting atmospheric radiance at first and second predetermined distances in front of the aircraft and at first and second elevations separated by a predetermined elevation angle,

said infrared sensor means comprising first and second rows of detector means for measuring the atmospheric radiance at first, second and reference wavelengths respectively, within the CO2/H2O) band,

a computer processing the radiance data at said first and reference wavelengths to determine whether an azimuth gradient of decreasing temperature exceeding a predetermined threshold exists in the atmosphere,

said computer processing the radiance data at said first and second wavelengths to determine atmospheric lapse rate,

an inertial sensor means for detecting accelerations experienced by the aircraft,

said computer means processing information from said infrared sensor means to adjust the sensitivity of acceleration detection to allow an advanced reactive warning of the presence of windshear.