Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Aeronautical vehicle
Reexamination Certificate
2000-02-01
2002-11-05
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Aeronautical vehicle
C701S016000, C701S205000, C340S945000, C340S972000
Reexamination Certificate
active
06477449
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to ground proximity warning systems for use in aircraft. More particularly, the apparatus, methods, and computer program products of the present invention relate to determining a corrected distance between an aircraft and a selected runway to thereby account for the altitude of the aircraft above the selected runway as the aircraft approaches the runway.
BACKGROUND OF THE INVENTION
An important advancement in aircraft flight safety has been the development of ground proximity warning systems. These warning systems analyze the flight parameters of the aircraft and the terrain surrounding the aircraft. Based on this analysis, these warning systems provide alerts to the flight crew concerning possible inadvertent collisions with terrain or other obstacles.
Two important aspects of ground proximity warning systems are the need to operate independent of user input and the need to reduce the number of nuisance alarms provided to the flight crew. In light of this, at least one ground proximity warning system has been developed that, for the most part, operates independent of user input and provides mechanisms to reduce the number of nuisance alarms published to the flight crew.
Specifically, to operate independent of user input, this ground proximity warning system continuingly selects a runway that is near the current position of the aircraft. The global coordinates and elevation of the selected runway are used by the ground proximity warning system for ground proximity warning calculations. For instance, the ground proximity warning system uses the flight parameters of the aircraft, such as the position, altitude, ground speed, track and heading of the aircraft, and the global coordinates and elevation of the selected runway to construct terrain clearance floor envelopes about the aircraft. Based on these terrain clearance floor envelopes, the ground proximity warning system provides alarms to the flight crew of any impending intersection of the flight path with terrain or obstacles.
In addition to aiding in the generation of terrain clearance floor envelopes independent of user input, the selected runway is also used to reduce the number of nuisance alarms generated. Specifically, the ground proximity warning system alters the terrain clearance floor envelopes based on the distance between the aircraft and selected runway to prevent the occurrence of nuisance alarms. As the aircraft approaches the selected runway, the terrain clearance floor envelopes are typically altered to reflect a landing approach pattern for the aircraft. Alteration of the terrain clearance floor envelopes based on a landing pattern reduces the number of nuisance alarms generated.
The ground proximity warning system also uses a restricted look ahead distance to reduce the occurrence of nuisance alarms. The restricted look ahead distance represents a distance ahead of the aircraft in which the ground proximity warning system will provide warnings to the flight crew. By restricting the distance in front of the aircraft for which alarms are generated, the number of nuisance alarms is reduced.
The number of nuisance alarms is also reduced by basing the value of the look ahead distance as a function of the distance between the aircraft and the selected runway. As an aircraft approaches a runway for landing, the ground proximity warning system reduces the value of the look ahead distance based on the proximity of the aircraft to the selected runway. Specifically, as illustrated in
FIG. 1
, the ground proximity warning system typically uses the coordinate distance
14
between the aircraft
10
and selected runway
12
for ground proximity warning calculations. With reference to
FIG. 2
, the ground proximity warning system determines the look ahead distance value by comparing a distance between the aircraft and selected runway to a look ahead distance equation, such as the equation depicted graphically in FIG.
2
:
LAD
Dist. to Runway
=(3.25/6)(Distance to Runway)−0.3333,
for look ahead distance (LAD) values between 0.75 nm≦LAD≦4 nn corresponding to distances between the aircraft and runway of 2 to 8 nm. The look ahead distance equation is designed to reduce the look ahead distance of the ground proximity warning system as the aircraft approaches the runway to thereby reduce nuisance alarms.
While the use of a selected runway for terrain clearance floor envelopes and look ahead distance calculations is advantageous as it allows the ground proximity system to operate independent of the user input, there are some drawbacks. Specifically, because the ground proximity warning system does not receive user input concerning the destination of the aircraft, as the aircraft approaches the selected runway, the terrain clearance floor envelopes and look ahead distance value are typically reduced as though the aircraft is landing on the selected runway. Although reduction of the look ahead distance value and terrain clearance floor envelopes is advantageous for reducing nuisance alarms when the aircraft is actually landing on the runway, it may be less advantageous when the aircraft is merely flying near the runway en route to another destination.
To address this problem, the conventional ground proximity warning system typically places a lower limit on the look ahead distance value, if the aircraft has an altitude with respect to the runway that is greater than a predetermined altitude. For example, if the altitude of the aircraft above the runway is greater than 3500 ft, the ground proximity warning system may limit the look ahead distance value (LAD
Dist. to Runway
) to a minimum value of, for example, 2.375 nm. As such, as the aircraft approaches the selected runway, the look ahead distance value will be reduced by the equation depicted graphically in
FIG. 2
until the look ahead distance value is equal to the minimum look ahead distance value, i.e., 2.375 nm, at which point the look ahead distance value is no longer reduced, as depicted in dashed lines.
Although limiting the look ahead distance value to a minimum value based on the altitude of the aircraft above the runway is advantageous, there are some drawbacks to this approach. Specifically, the conventional ground proximity system does not adjust the minimum look ahead distance value for an aircraft that has an altitude with respect to the runway that is significantly higher than the predetermined altitude. For example, if the predetermined altitude is 3500 ft, an aircraft that is 20,000 ft above the selected runway will have the same minimum look ahead distance value as if the aircraft is 3500 ft above the selected runway. In light of this, a ground proximity warning system that accounts for the altitude of the aircraft above the selected runway in determining a distance between the aircraft and selected runway for ground proximity warning calculations would be desirable.
SUMMARY OF THE INVENTION
As set forth below, the apparatus, methods, and computer program products of the present invention may overcome many of the deficiencies identified with the use of the distance between an aircraft and selected runway for ground proximity warning calculations. The present invention provides several apparatus, methods, and computer program products for determining a corrected distance between an aircraft and a selected runway. Specifically, the present invention selects either the coordinate distance between the aircraft and the selected runway or a calculated distance value as the corrected distance value for ground proximity warning calculations. The calculated distance value is a distance value calculated based on a mathematical relationship between the altitude of the aircraft and a predetermined glideslope. The predetermined glideslope value is a maximum glideslope, above which, the aircraft is most likely not landing on the selected runway. The determination of the corrected distance between the aircraft and selected runway is therefore based on the aircraft's altitude and positio
Conner Kevin J
Johnson Steven C.
Cuchlinski Jr. William A.
Honeywell International , Inc.
Pipala Edward J.
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