Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Aeronautical vehicle
Reexamination Certificate
2002-09-19
2004-01-20
Nguyen, Tan Q. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Aeronautical vehicle
C701S009000, C701S120000, C340S005730, C348S143000
Reexamination Certificate
active
06681158
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to aircraft surveillance systems, and more particularly to secure aircraft surveillance systems that are configured for alerting air traffic controllers if an aircraft departs substantially from an expected flight path or pattern of behavior.
BACKGROUND OF THE INVENTION
The terrorist hijacking and suicide crashes of four U.S. civilian airliners on Sep. 11, 2001, were tragic and unforeseen. The inability of the air traffic control and civil defense infrastructure to respond effectively to the situation as it developed was due, in part, to limitations of the current radar-based surveillance infrastructure.
Because of timing delays and accuracy limitations inherent in the design of current radar-based air traffic control systems, controllers are unable to determine the real-time intent of aircraft they are tracking. Moreover, current radar surveillance systems depend on transponder responses from the aircraft to operate at maximum efficiency. The September 11 terrorists disabled or turned off some aircraft transponders in the cockpit of the hijacked aircraft, making it difficult to track the aircraft. This, combined with the limitations of current surveillance radar systems, made it nearly impossible for controllers to realize that three of the aircraft had turned into collision courses with ground targets.
Thus, there is a need for an aircraft surveillance system that cannot be interrupted by unauthorized persons. There is a further need for an improved surveillance system that is configured to warn ground controllers when an aircraft acts outside of cleared parameters. Furthermore, there is a need for systems that alert ground controllers if someone in the aircraft is attempting to send a false signal to deceive the controllers into believing that the aircraft is following a planned course when in fact it has been diverted. In addition, there is a need for an improved surveillance system that allows pilots to quickly and reliably issue a distress signal upon realizing that their aircraft is in danger of being hijacked.
SUMMARY OF THE INVENTION
The present invention meets the objectives set forth above by providing an on-board broadcast surveillance system and method that cannot be interrupted and that provides three-dimensional position information to ground or airborne controllers via a data transmitter. Optionally, the broadcast information may include the Ownship aircraft's aircraft ID and intended path. Other optional components according to the invention include a system and method for validating messages received from the aircraft, and an alternative system and method for determining the aircraft's position if a primary navigation aid, such as the Global Positioning System (“GPS”), is not available.
In a preferred embodiment, the invention equips an aircraft with a small uninterruptible Universal Access Transceiver/Automatic Dependent Surveillance—Broadcast (“UAT/ADS-B”) transmitter (or other suitable transmitter) that is capable of broadcasting aircraft ID, three-dimensional position and aircraft intent. The device contains an internal GPS receiver to determine aircraft position and has an uninterruptible power supply that can not be disabled from the cockpit. The device, which is preferably located in the aircraft's equipment bay, automatically begins broadcasting aircraft position, ID and intent the moment the aircraft is powered up and continues to broadcast that information, in real-time, until the aircraft is on the ground and shut down. Via an optional external interface, the device may receive and broadcast flight plan information from the on-board flight management computer. Such information is then made available for comparison to originally filed ATC flight plan data. This allows air traffic control (“ATC”) authorities to detect any inappropriate changes to the aircraft's intended destination shortly after the changes are entered into the aircraft's flight management computer.
The invention may further provide a ground infrastructure that preferably comprises a plurality of receivers for receiving the information transmitted from the aircraft. Preferably, about 600 low-cost UAT ADS-B receivers would be located throughout the continental United States to provide full CONUS real-time surveillance. The system would be equipped with the capability of determining whether the equipped aircraft were flying within the “normal” parameters of its flight plan. Upon detecting a deviation from the flight plan, the system would provide controllers and civil defense authorities with an immediate alert. If an aircraft deviated from its flight plan, its ADS-B signal would continue to provide real-time position, altitude, heading and intent of the aircraft to air traffic control and civil defense authorities. Airborne controller stations may optionally replace some or all ground controller stations.
A system and method for validating messages received from the aircraft may be based on the ability of the UAT to perform range measurements based on signal propagation time, giving rise to several advantages. More specifically, the system can determine whether the aircraft's reported position (i.e., the position transmitted by the aircraft) is valid by comparing a range that corresponds to the target's reported position with a range derived from signal propagation times. As an additional validity check, or if GPS service is unavailable, the position of a particular aircraft can be determined by receiving at least a partial State Vector (identity plus altitude) at multiple controller stations, and then using time of reception differentials among a network of such stations to compute lines of position.
Additional anti-spoofing can be accomplished by validating the last received position information with a dead reckoning algorithm. When implementing this functionality, any jumps in speed and velocity outside a preset limit are rejected.
In the event that GPS position information becomes unavailable, a dead reckoning function can be used to estimate the aircraft's position. Inexpensive inputs such as heading from a magnetic flux gate, changes in velocity from a solid state accelerometer, and altitude from an optional self-contained barometer can also be used to enhance the dead reckoning calculation. As will be understood by one skilled in the art, this self-contained barometer is optional because the aircraft is preferably equipped with an altimeter that is not affected by any loss of GPS position information.
The invention may further include a panic button within the cockpit of the aircraft that, when activated, transmits a signal to an aircraft information broadcasting system indicating that the Ownship aircraft is in danger of being hijacked. The aircraft information broadcasting system then immediately transmits a signal that triggers an appropriate alarm at a ground station. This aspect of the system is advantageous because it allows pilots to issue a distress signal without having to enter a complex code. Also, in a preferred embodiment of the invention, the aircraft information broadcasting system is preferably tamper-proof and located outside the aircraft's cockpit. As a result, it is unlikely that a hijacker would be able to disable the aircraft information broadcasting system before the pilot transmits a distress signal to air traffic control.
More particularly, a system according to a preferred embodiment of the invention comprises a housing defining an interior portion and an aircraft information broadcasting system that is disposed within the interior portion of the housing. In this embodiment of the invention, the system is configured for broadcasting flight-related information that is related to the Ownship aircraft's current flight. The housing is configured for restricting access to the aircraft information broadcasting system while the aircraft is in flight.
In one embodiment of the invention, the system is configured for broadcasting the flight-related informati
Griffith Emmett
Hudson Craig
Mosher Thomas Lee
Garmin AT, Inc.
Nguyen Tan Q.
Rolf Devon A.
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