Communications: electrical – Aircraft alarm or indicating systems – Flight alarm
Reexamination Certificate
1999-11-29
2001-07-10
Swarthout, Brent A. (Department: 2736)
Communications: electrical
Aircraft alarm or indicating systems
Flight alarm
C073S17800T, C340S946000, C340S963000, C701S015000
Reexamination Certificate
active
06259379
ABSTRACT:
This application is related to concurrently filed and commonly assigned patent applications entitled “Ground Proximity Warning System and Methods for Rotary Wing Aircraft” (Attorney Docket No. 543-96-007/T-S-004), and “Systems and Methods for Generating Altitude Callouts for Rotary Wing Aircraft” (Attorney Docket No. 543-96-008/T-S-006), the complete disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates generally to ground proximity warning devices and more particularly to systems and methods for enabling such ground proximity warning devices in rotary wing aircraft.
Ground proximity warning systems provide aural and visual warnings of aircraft descent after takeoffs, landings, during a go-around after a missed approach and other low altitude flying conditions. These systems typically detect altitude loss by computing the barometric altitude (MSL) rate change. The radio altitude or altitude above ground level (AGL) is then determined with a radio altimeter. The warning device typically issues a number of aural or visual warnings if the altitude loss is excessive for the radio altitude at which the aircraft is flying. For example, one such system, compares the accumulated altitude loss after takeoff of the aircraft, and generates a warning if the altitude loss exceeds a predetermined value before a threshold altitude has been reached. Examples of such a system are disclosed in commonly assigned U.S. Pat. Nos. 3,946,358, 3,947,808 and 4,818,992, the complete disclosures of which are incorporated herein by reference. Another type of warning system warns the pilot in the event that the aircraft if descending too rapidly, particularly on approach to a landing. Examples of this type of warning system are disclosed in commonly assigned U.S. Pat. Nos. 3,958,358 4,215,334 and 4,551,723, the complete disclosures of which are also incorporated herein by reference.
The present invention is particularly concerned with ground proximity warning devices for rotary wing aircraft, such as helicopters. Most conventional ground proximity warning systems are designed to operate with transport aircraft, particularly with large turbine powered aircraft, such as those flown by commercial airlines. Since rotary wing aircraft are highly maneuverable, they typically have flight operational characteristics entirely different than that of transport aircraft. Consequently, the systems designed for transport aircraft can generate nuisance warnings during certain normal operational conditions in rotary wing aircraft. In addition, these warning systems may provide no warning or an inadequate warning during other flight conditions. Thus, a pilot may tend to ignore the warnings provided by such systems, rendering them ineffective.
SUMMARY OF THE INVENTION
The present invention provides ground proximity warning systems and methods for rotary wing aircraft such as helicopters. The warning system of the present invention includes an air ground detection device disposed on the aircraft to confirm whether the aircraft is on the ground or in the air. A controller is coupled to the air ground detection device and configured to move between a ground state when the aircraft is on the ground and an airborne state when the aircraft is in the air. The controller may be used for a variety of applications within the aircraft, such as disabling a ground proximity warning device when the aircraft is on the ground and enabling the warning device when the aircraft is in the air. In addition, the air ground controller may be used to signal the beginning and the end of a flight for the aircraft's flight history fault memory. For example, when the controller switches from the ground state to the airborne state, the warning may include a switch for enabling the flight history fault memory. When the control switches back to the ground state, the switch will disable the flight history flight memory to signify the end of the flight.
In a specific configuration, the warning system includes one or more sensors for sensing certain aircraft conditions that will indicate whether the aircraft is on the ground or in the air. Preferably, the sensors include one or more force sensors placed on or near the aircraft's wheel to detect the weight placed thereon. When the weight is above a threshold level that indicates the aircraft's weight is being placed on the wheels, the controller will switch into the ground state. When the weight falls below the threshold level, the controller will switch back to the airborne state indicating that the aircraft has taken off. The control system further includes a latch that holds the controller in either the airborne or ground state until it is reset by one or more flight conditions. For example, prior to takeoff, the latch will hold the controller in the ground state. The latch will not reset and allow the controller to move into the airborne state until the force sensor(s) detect an aircraft weight greater than the threshold weight.
The weight sensors are typically placed exterior to the aircraft and, therefore, are subject to environmental conditions such as adverse weather and the like. Accordingly, the invention may include an additional, redundant detection method to prevent erroneous airborne indication due to errors in the weight sensors. In an exemplary embodiment, the system further includes one or more engine torque detectors for detecting the total engine torque of one or more of the aircraft's engines. In this embodiment, the controller will move into the ground state when the weight on the wheels is above the threshold level and when the engine torque is below a threshold level, which would indicate that the aircraft is not providing enough torque to lift the helicopter above the ground.
In an exemplary embodiment, a ground proximity warning computer is provided for a rotary wing aircraft, e.g., a Sikorsky S-76 Aircraft. The warning computer provides warnings to the pilot when the aircraft is in danger of impacting the earth. The aircraft data is collected from various sensors on the aircraft and processed in a digitally controlled warning computer to determine if the aircraft is in danger. Visual and aural outputs advise the pilot of dangerous situations and indicate if the system is operational. According to the present invention, the warning computer includes a ground proximity warning device having an alarm for generating a visual and/or aural warning based on one or more flight condition(s) of the aircraft. This ground proximity warning device can provide a variety of warnings to the pilot(s), such as excessive descent rate, excessive closure to terrain, altitude loss after take-off, unsafe terrain clearance, altitude awareness callouts and the like.
The controller of the present invention is coupled to one or more of the warning devices and disposed to disable the warning devices when the aircraft is on the ground. Consequently, the warning devices will generate less nuisance warnings during certain normal operational conditions of the rotary wing aircraft so that the pilot will not be tempted to ignore the warnings provided by such systems.
REFERENCES:
patent: 4293840 (1981-10-01), Hadari
patent: 4355294 (1982-10-01), Ben-David et al.
patent: 4987413 (1991-01-01), Grove
patent: 5666110 (1997-09-01), Paterson
patent: 5826833 (1998-10-01), Evans et al.
Loos Alden L.
Ostrom Gary A.
Paterson Noel S.
Allied-Signal Inc.
Swarthout Brent A.
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