Patent ID: 6584384
Filing Date: 2003-06-24
Classification: G01C

Abstract:
An apparatus for detecting faults in aircraft altimetry comprising:(a) a first logic having: (i) an input coupled to receive a Gray-coded altitude; and (ii) error logic to detect an error in said Gray-coded altitude; (iii) an output for asserting a first error signal when said error is detected; (b) a second logic having; (i) an input coupled to receive a pressure altitude data and a secondary source of altitude data; (ii) altitude rate logic to compare a first rate of change of said pressure altitude data and a second rate of change of said secondary source of altitude data; and (iii) an output for asserting a second error signal when said first and second rate of change differ by more than a predetermined amount; (c) a third logic having: (i) an input coupled to receive said pressure altitude data and a tertiary source of altitude data; (ii) a comparison logic to obtain a difference between said pressure altitude and said tertiary source of altitude data; (iii) a error budget logic that obtains an error budget based on known characteristics of said pressure altitude data and said tertiary source of altitude data; (iv) an output for asserting a third error signal when said difference exceeds said error budget; and (d) an alerting logic having: (i) an input coupled to receive said first error signal, said second error signal and said third error signal; and (ii) an output for asserting an alert signal when at least one of said first error signal, said second error signal and said third error signal is asserted.