Patent Description:
While wake turbulence can be a threat to safety of any aircraft, it is particularly dangerous for medium to small aircraft. Such wake turbulence is particularly dangerous immediately before landings and immediately after takeoffs. The task of avoiding potential wake turbulences of other aircraft is made more difficult when a pilot of an aircraft is forced to monitor the position and flight path history of multiple other aircraft.

<CIT>) discloses a system and method to display, when within an envelope of an ownship's flight path, a symbol representing wake turbulence from another aircraft based on aircraft type and flight parameters received from the other aircraft, the symbol being formatted to indicate the severity of portions of the wake turbulence. The format is modified periodically in accordance with the aircraft's flight path and a decay rate of the wake turbulence.

<CIT>) discloses a method for estimating the effect of environmental conditions on an aircraft, including measuring the motions of an aircraft; estimating the expected motions of the aircraft, wherein the expected motions of the aircraft are estimated using information regarding the aircraft's control inputs and/or control surface positions; and estimating, based on the measured motions of the aircraft and the expected motions of the aircraft, the forces exerted on the aircraft by the environmental conditions, wherein the forces are estimated based on a difference between the measured motions of the aircraft and expected motions of the aircraft.

<CIT>) discloses a computer method for determining potential wake turbulence by a first aircraft from wake generated by a second aircraft. The computer method includes receiving a signal generated by the second aircraft at the first aircraft and transforming the signal to a first wake turbulence boundary that represents the wake generated by the second aircraft. An intersection volume, which is representative of a zone of dangerous turbulence interactions, is selected for the first aircraft. Based on a determination of intersection between the first wake turbulence boundary and the intersection volume, issuing a warning flag if an intersection exists or continue generating the first wake turbulence boundary and determining whether interactions exist.

The present disclosure provides a avionic wake turbulence awareness system as detailed in claim <NUM> and a method of wake turbulence awareness in an aircraft according to claim <NUM>. Advantageous features are provided in dependent claims.

The present invention provides awareness to a pilot of a risk posed by wake turbulence of other aircraft. Moreover, the present invention may be implemented as a system that is based upon information that is readily available from avionic systems of even small aircraft to provide awareness of a risk of encountering such wake turbulence. The invention is based upon a recognition that it is difficult for a pilot to visually estimate the distance of another aircraft and/or the time it may take to reach the flight path of that aircraft and any accompanying potential wake turbulence. As a result of such inaccuracy, it is possible for the pilot to encounter a wake turbulence even when the pilot estimates that the aircraft is sufficiently spaced from another aircraft. ADS-B systems are becoming popular in aircraft of all sizes and will soon be required on most aircraft systems. ADS-B systems receive transmissions from other aircraft in the form of an <NUM> character field that consists of either a flight identifier for a commercial airliner or a tail number for general aviation aircraft, as well as the relative position of the identified aircraft with respect to the equipped aircraft. With such information, the control system of the equipped aircraft creates a flight path history for each aircraft in its vicinity. Wake turbulence caution areas that follow each of those other aircraft are defined by their aircraft type and follow the respective bread crumbs of the their respective flight path histories. In other words, this wake turbulence caution area may be modified to account for lead aircraft type, typical wake vortex, descent rate, reported winds, and the like. By tracking the flight path history of an intruding aircraft, the system of the equipped aircraft can provide a visual and/or aural advisory to the pilot of a potential wake turbulence associated with the intruding aircraft. The system also reports to the pilot the time and distance from the lead aircraft which will aid the pilot in keeping appropriate spacing from the lead aircraft.

These and other objects, advantages, and features of this invention will become apparent upon review of the following specification in conjunction with the drawings.

Referring now to the drawings and the illustrative embodiments depicted therein, an avionics wake turbulence awareness system for use in an aircraft is disclosed. <FIG> illustrates an exemplary avionics wake turbulence awareness system <NUM>. As discussed herein, a receiver <NUM> of the wake turbulence awareness system <NUM> may be an ADS-B receive that is capable of receiving ADS-B transmissions from other aircraft. The transmission be in the form of an <NUM>-character field that consists of either a flight identifier for a commercial airliner or a tail number for a general aviation aircraft, as well as the relative position of the identified aircraft with respect to the equipped aircraft. The wake turbulence awareness system <NUM> includes a control system <NUM> (also known herein as a controller <NUM>) that is responsive to the ADS-B receiver <NUM> in order to receive transmissions from other aircraft. The wake turbulence awareness system <NUM> may include any form of ADS-B receiver <NUM> and accompanying controller <NUM>, and may be of the type disclosed in commonly assigned <CIT>, entitled MULTI-LINK TRANSPONDER FOR AIRCRAFT AND METHOD OF PROVIDING MULTI-LINK TRANSPONDER CAPABILITY TO AN AIRCRAFT HAVING AN EXISTING TRANSPONDER,. As also discussed herein, and described in detail in commonly owned <CIT>, entitled "AIRCRAFT TRAFFIC DISPLAY," ADS-B signals are received by the ADS-B receiver <NUM>, and the controller <NUM> accessing a database in a memory <NUM>, looks up specific aircraft information based upon a received ICAO code contained within the ADS-B transmission. As illustrated in <FIG>, the wake turbulence awareness system <NUM> also includes an output device <NUM>, which comprises a visual display screen <NUM>. The output device <NUM> may also optionally include an annunciator <NUM>. The annunciator <NUM> may be implemented as one or more speakers in the aircraft and via a pilot's aural headset. The output device <NUM> is responsive to the control system <NUM> to provide guidance to a pilot of the equipped aircraft to avoid encounters with potential wake turbulences of other aircraft.

<FIG> illustrates that the ADS-B receiver <NUM> of <FIG> may comprise a <NUM> ES receiver 102a and/or a <NUM> UAT receiver 102b. As illustrated in <FIG>, either of the <NUM> ES receiver 102a and the <NUM> UAT receiver 102b forwards the received ADS-B transmissions to the controller <NUM> for processing.

<FIG> illustrates an exemplary output device <NUM> that incorporates a display screen <NUM> and an annunciator <NUM>. The guidance includes a visual distance indication <NUM> indicating a distance in nautical miles to another aircraft. The guidance includes a time indication <NUM> advising the pilot of an estimated time behind the other aircraft or to the potential wake encounter computed at least in part from the ADS-B system. The guidance may include a visual indication <NUM> that the equipped aircraft is at risk of encountering the wake turbulence caution area of the other aircraft. In an aspect of the present invention, an icon <NUM> is used as a visual indication <NUM>. As illustrated in <FIG>, the icon <NUM> may be placed adjacent a depiction of the other aircraft on the display <NUM>. The icon <NUM> may take other forms, but is shown as a chevron trailing the depiction of the other aircraft on the display <NUM>. As discussed below, and illustrated in <FIG>, the icon <NUM> may be paired with a visual depiction of the flight path history <NUM> of the other aircraft in order to give the pilot a better understanding of the form of potential wake turbulences that should be avoided. As illustrated in <FIG>, and discussed herein, such visual indication of the flight path <NUM> of the other aircraft may be in the form of dotted "bread crumbs" or other intuitive indications of the flight path history <NUM> of the other aircraft.

As illustrated in <FIG> and <FIG>, the output device <NUM> may include an aural annunciator <NUM> that verbally notifies the pilot via an aural announcement that the equipped aircraft is at risk of encountering the wake turbulence caution area of the other aircraft.

<FIG> illustrates the exemplary steps to a computer-implemented method for providing guidance to a pilot of an equipped aircraft that the equipped aircraft is at risk of encountering a wake turbulence caution area of another aircraft. In step <NUM> of <FIG>, an ADS-B Out message is received from an intruding aircraft. As used herein, an "intruding aircraft" is merely another aircraft leading the equipped aircraft that occupies the same general airspace as the equipped aircraft. Such an intruding aircraft has a potential wake turbulence that the equipped aircraft may need to avoid. In step <NUM> of <FIG>, the received ADS-B Out message is decoded to determine position, flight path, and aircraft ID of the intruding aircraft. In step <NUM> of <FIG>, data corresponding to the aircraft ID is retrieved from the database in the memory <NUM> based upon the determined aircraft ID.

In step <NUM> of <FIG>, vertical and horizontal limits of a wake turbulence caution area are determined based upon the determined aircraft type, speed, and flight path. As discussed herein, a wake turbulence caution area may be defined with regards to its length, height, and width. For example, the defined length may be three minutes in length, based upon the intruding aircraft's ground speed, a height or vertical dimension may be a thousand feet in height, while a width or horizontal dimension may also be a thousand feet in width. As discussed herein, the vertical and horizontal dimensions are variable based upon the intruding aircraft's category type. For example, larger aircraft types define larger horizontal and vertical dimensions. In step <NUM> of <FIG>, historical positions of the intruding aircraft are recorded in the memory <NUM>. Such recorded positions may be used, as discussed herein, to define the location of any potential wake vortex/turbulence.

In step <NUM> of <FIG>, the equipped aircraft's position and flight path are computed based upon positioning data received from a global positioning system (GPS) receiver <NUM> in the equipped aircraft. As illustrated in <FIG>, based upon signals received from orbiting GPS satellites, the GPS receiver <NUM> determines the position of the equipped aircraft and transmits the positioning data to the controller <NUM>. In step <NUM> of <FIG>, based upon the recorded historical positions of the intruding aircraft (i.e., a flight path history), and the computed position and flight path of the equipped aircraft, a distance and time from the equipped aircraft to the intruder and its associated wake turbulence caution area is determined. As discussed herein, once a location and flight history of the intruder aircraft is determined, the wake turbulence caution area may be defined.

In steps <NUM> and <NUM> of <FIG>, if the controller <NUM> determines that the equipped aircraft is at risk of entering the wake turbulence caution area associated with the intruder aircraft, a wake advisory will be transmitted to the output device <NUM>. In step <NUM> of <FIG>, a visual wake advisory is displayed in the display screen <NUM> and an audible wake advisory is announced in the annunciator <NUM>. As illustrated in <FIG>, the text box "WAKE," the icon <NUM> (e.g., chevrons), a determined nautical mile range <NUM> to the potential wake vortex/turbulence, and a determined time <NUM> to enter the wake turbulence caution area will be displayed on the display screen <NUM>. In an aspect of the present invention, if the equipped aircraft's flight path will enter the area of potential wake vortex/turbulence, or violate a recommended spacing between aircraft, the controller will indicate the above wake vortex/turbulence caution thirty seconds prior. As illustrated in <FIG> and <FIG>, when the WAKE caution is initiated, one or more of the visual display screen <NUM> and the annunciator <NUM> of the output device <NUM> will visually and/or audibly indicate the wake advisory, respectively.

The avionic wake turbulence awareness system <NUM> may receive ADS-B transmissions from multiple aircraft within the vicinity of the equipped aircraft. It is possible that more than one of these multiple aircraft may have a flight path history that indicates that there is a potential wake turbulence risk to the equipped aircraft. In an aspect of the present invention, the controller <NUM> may utilize a prioritization scheme that is capable of determining among the flight path histories of the multiple other aircraft, which of the multiple other aircraft creates a greatest risk of the equipped aircraft encountering the potential wake turbulence of that aircraft. The controller <NUM> may then provide guidance to the pilot of the equipped aircraft to avoid a potential encounter with the highest risk potential wake turbulence. Thus, the visual indication <NUM> may be displayed at only one aircraft depiction, and the distance <NUM> and time of separation <NUM> for only that intruding aircraft, even though multiple aircraft depictions may be displayed on the display screen <NUM>. This prioritization scheme avoids the pilot needing to make a choice as to which intruding aircraft needs to be avoided in order to take the least risky route.

In an aspect of the present invention, the avionic wake turbulence awareness system <NUM> may utilize a hierarchy to prioritize advisories, select a highest threat intruder, and suppress advisories for much smaller aircraft that would not create a significant wake vortex/turbulence as compared to the equipped aircraft. The tables below (Tables I & II) are an exemplary aircraft assignment for a six category system, as proposed by the Federal Aviation Administration (FAA). The list is not all-inclusive. As illustrated in Table I, aircraft models are categorized according to size, from Category A (the largest) to Category F (the smallest). Table II illustrates how the necessary separation between aircraft can vary according to the varying sizes of the leader aircraft and the follower aircraft. The minimum separation increases with the size ratio between the leading aircraft and the trailing aircraft. The minimum radar separation (MRS) is a variable minimum horizontal separation required between radar controlled aircraft, based upon their range from the controlling radar. For example, the MRS may be <NUM>-<NUM> nautical miles. The minimum required separation may be greater than the MRS, such as when the following aircraft type is smaller than the leading aircraft type.

<FIG> illustrate exemplary wake turbulence caution areas <NUM> and how the dimensions of the wake turbulence caution area <NUM> are defined by the type of intruder/leading aircraft and related information. As illustrated in <FIG>, an exemplary wake turbulence caution area <NUM> may be three minutes in length, based upon the ground speed of the intruder/leading aircraft. The exemplary wake caution area's vertical dimension, extending below the altitude of the intruder/leading aircraft, may be a notional <NUM> feet for category A-D types, and a notional <NUM> feet for category E & F types. As illustrated in <FIG>, the wake caution area <NUM> extends below the intruder/leading aircraft because a wake turbulence may drift down over time. As illustrated in <FIG>, the wake turbulence caution area's exemplary width may also vary according to category type. For example, the width may also be a notional <NUM> feet for category A-D types, and a notional <NUM> feet for category E & F types. As noted herein, the exemplary length, width, and height values are notional, and other dimensions based on category types are anticipated.

<FIG> illustrate exemplary wake turbulence caution areas <NUM> that are shaped to follow the flight path histories <NUM> of the intruder/leading aircraft. In other words, a wake turbulence caution area's dimensions will conform to the path of a flight path history as it moves in three dimensions.

Thus, embodiments of the present invention are capable of improving safety by providing quantitative separation information for a flight operation that is typically performed visually using the pilot's judgement. In addition, the system provides awareness to a developing or potential wake turbulence encounter that may not be readily apparent to the pilot, such as crossing flight paths that may occur during any phase of the flight. This may be accomplished because the flight paths of both aircraft may be known from the controller <NUM> that is responsive to the ADS-B receiver <NUM>.

Claim 1:
An avionics wake turbulence awareness system (<NUM>) for use in an aircraft, the system comprising:
an ADS-B receiver (<NUM>) adapted to be positioned in an equipped aircraft and operable to receive ADS-B transmissions from a plurality of other aircraft;
a control system (<NUM>) configured to, based on information from the received ADS-B transmissions received by the ADS-B receiver (<NUM>), determine an identity for each of the plurality of other aircraft and configured to determine a movement of each of the plurality of other aircraft relative to the equipped aircraft;
wherein the control system (<NUM>) is configured to determine a flight path history of each of the plurality of other aircraft from their respective identities and movements relative to the equipped aircraft; and
an output device (<NUM>), responsive to the control system (<NUM>), configured to provide guidance to a pilot of the equipped aircraft to avoid an encounter with a wake turbulence caution area that is defined by a flight path history of a selected aircraft of the plurality of other aircraft; and
wherein the control system (<NUM>) is configured to evaluate the relative risk of the equipped aircraft encountering respective wake turbulence caution areas of each of the plurality of other aircraft, and configured to, after selecting an aircraft of the plurality of other aircraft with a highest relative risk based upon the evaluation of the respective wake turbulence caution areas, provide guidance to the pilot of the equipped aircraft to avoid an encounter with a wake turbulence caution area of the selected aircraft, wherein the guidance comprises distance and flight time to the selected aircraft.