Abstract: A method and system compares combinations of vehicle or aircraft state variables against known combinations of potentially dangerous states. Alarms and error messages are selectively generated based on such comparisons. In one embodiment, pairs of aircraft state variables are selected and compared to known undesirable pairs of state combinations that indicate an error or a condition that a crew should monitor closely. The combinations and error messages are provided by the database. The comparisons are conducted on a periodic basis monitoring real time states of the parameters collected from various sensors and commands. Experts considering a matrix that provides an exhaustive pairwise comparison of potentially important state variables initially identify undesirable state combinations. Error messages and identification of potential alarms are generated based on both knowledge of actual accidents, and on use of expert knowledge to predict potentially dangerous states.

Abstract: Method and system for analyzing, separately or in combination, kinetic energy and potential energy and/or their time derivatives, measured or estimated or computed, for an aircraft in approach phase or in takeoff phase, to determine if the aircraft is or will be put in an anomalous configuration in order to join a stable approach path or takeoff path. A reference value of kinetic energy and/or potential energy (or time derivatives thereof) is provided, and a comparison index for the estimated energy and reference energy is computed and compared with a normal range of index values for a corresponding aircraft maneuver. If the computed energy index lies outside the normal index range, this phase of the aircraft is identified as anomalous, non-normal or potentially unstable.

Abstract: A method, apparatus and computer program product for assisting the pilot of an aircraft in making a go-around decision. Various aircraft parameters are monitored during the approach to land and a risk level assessed. When the risk level exceeds a specified threshold, an alert is provided.

Abstract: Methods and systems are disclosed for preventing aircraft collisions with forward looking terrain avoidance (FLTA) functionality based on a terrain avoidance profile used to evaluate potential terrain threats based on the projected flight path of an aircraft in flight, and a clear terrain profile to determine whether the terrain threat has been cleared. If the terrain avoidance profile conflicts with terrain, a collision threat may exist whereby the pilot is notified and a terrain avoidance maneuver is executed. During the terrain avoidance maneuver the clear terrain profile extends in a direction substantially parallel with the horizon at or near the present altitude of the aircraft to check whether it is safe to return to the previous flight path angle or otherwise end the terrain-avoiding maneuver. When the clear terrain profile no longer conflicts with the terrain threat, a terrain clear indicator is then issued to the pilot.

Abstract: There is disclosed a system and method wherein precise geographical location information such as Global Positioning System coordinate data is utilized as a principal criterion for implementing other wireless transmitted instructions and communications advising aircraft of nearby restricted areas, the proximity of a hazardous condition, or virtually any other situation which is relevant to the intended recipient because of their location. The system and method further can involve intervention and control of a vehicle, such as an aircraft or automobile, which comes into a predetermined location or area, or under other circumstances. The system and method use transmitting units and receiving units, both of which can receive geographical positioning information and which may sound or otherwise output an appropriate advisory, warning or other communication selected based on their positions, heading, and/or speed.

Abstract: An improved method for correlating between targets in an air traffic control system. A methods or systems according to the invention compare selected components of a first target report to the components of a second target report, produce a confidence level on each component comparison, and determine whether to declare the targets similar based on the confidence level on each component compared. The first and second target reports may include ADS-B target reports and TIS target reports. The individual components of the reports may be range, bearing, track angle, and relative altitude. The methods or systems may use a fuzzy logic probability model to produce a continuous confidence level on each component comparison.

Abstract: A system and a method for providing a continuous, semi-continuous and/or repetitive aural signal to an aircraft pilot indicative of a difference between a set value and an actual value for one or more flight characteristics of the aircraft.

Abstract: A flight information display for the flight deck of an aircraft showing a pictorial side view of the flight path or the area directly in front of the aircraft area having a selected distance of at least 0.5 nautical miles, comprising (a) a pictorial representation to scale of the profile of the highest elevations of a swath of terrain along said path or area, (b) an icon positioned on the left or right side of the display representing the aircraft, the altitude of which is to scale with the height of the terrain, and (c) an altitude reference scale; wherein the width of the swath is at least 0.1 nautical miles and no greater than the distance of the minimum accuracy of the means for determining the aircraft's location.

Abstract: A system for monitoring an aircraft receives navigation signals and deriving a position vector therefrom and also receives an input representative of altitude of the aircraft above ground level. The system samples the position vector at a selected sample rate and outputs a succession of samples of the position vector, the sample rate depending on whether the altitude of the aircraft above ground level is less than a predetermined value. Data packets that contain respective samples of the position vector are transmitted to a ground-based receiving station. The ground-based receiving station may calculate secondary data.

Abstract: An avionics system and method is employed for alerting pilots of low premature descent during final landing approach. The method involves determining Final Approach Flight Safety Altitudes for a plurality of runways, identifying which runway an aircraft is likely to land on, and alerting the pilot if the aircraft altitude is lower than the final approach flight safety altitude. The method takes into account terrain information, airport and runway information, and aircraft reference data to make its determination. Particular embodiments reference the Final Approach Fix, one or more step down fix values, the Minimum Descent Altitude and the Missed Approach Point in calculating the Final Approach Flight Safety Altitudes. The system and method have particular utility with a Terrain Awareness and Warning System (“TAWS”) and display in an aircraft.

Abstract: An improved system and methods for correlating an interrogation-based air traffic surveillance intruder, such as an Traffic alert and Collision Avoidance System (TCAS) intruder, and a GPS-based air traffic surveillance target, such as an Automatic Dependent Surveillance Broadcast (ADS-B) target to minimize or eliminate the display of two symbols for the same intruder/target on the CDTI of an aircraft. The method comprises the steps of receiving ADS-B data at a processing unit and calculating select component deltas for the ADS-B data versus an entry in a TCAS intruder file. Progressive weights are assigned to the deltas and the progressive weights are summed, resulting in a total confidence score. Total confidence scores of ADS-B target and TCAS intruder pairs are compared to determine correlation between the ADS-B target and the TCAS intruders.

Abstract: The present invention provides for a computer that accepts inputs from a surface monitor to determine whether the terrain below the aircraft is water or land. In a preferred embodiment an improved landing gear warning system is provided to warn a pilot when landing gear of an aircraft are in the improper configuration for a landing on a particular surface. The warning system comprises a computer operatively connected to a surface monitor and a gear-status warning indicator. The computer also accepts an input from the gear status sensors to determine if the landing gear is extended or retracted. If the system senses a water surface and the landing gear is down, a warning light and/or buzzer alerts the pilot that the landing gear is in the incorrect configuration. If the landing surface is land and the gear is up, the “gear status” indicator warning is initiated.

Abstract: An apparatus, method and computer program product for alerting rotary wing aircraft of potentially hazardous proximity to terrain also reduces nuisance warnings and provides a terrain display consistent with the unique performance capabilities of such aircraft.

Abstract: Pilot error is reduced and auto pilot operation is improved by the addition of capture information to the information provided on a cockpit display. The capture information, such as, for example, capture start point, last point to initiate capture, trajectory during capture, and capture overshoot region provide information to the pilot regarding the correct initiation of capture. Pilots are therefore better able to evaluate the ongoing performance of the automation or auto pilot systems and to trust that the auto pilot is functioning as desired. Furthermore, the pilot operating the aircraft in manual mode receives guidance based on this information to better know when to initiate capture of the assigned altitude or vertical path.

Abstract: A method for satellite receiver autonomous integrity monitoring (RAIM) real time fault detection and exclusion implementation comprising the following steps: (1) continuously computing a horizontal protection level (HPL) and a vertical 32 protection level (VPL) associated with the effective configuration of real time measurement geometry; (2) if the HPL is less than or equal to the horizontal alert limit (HAL), and/or if the VPL is less than or equal to said vertical alert limit (VAL); declaring the RAIM detection function available; (3) continuously computing a horizontal exclusion level (HEL) and continuously computing a vertical exclusion level (VEL) associated with the effective configuration of real time measurement geometry; and (4) if the HEL is less than or equal to the HAL, and/or if the VEL is less than or equal to the VAL, declaring the RAIM fault exclusion function available.

Abstract: An apparatus, method and computer program product for displaying terrain and terrain alerts to pilots of rotary wing aircraft provides a terrain display consistent with the performance capabilities of such aircraft.

Abstract: A free flight obstacle avoidance system (OAS) is a commanded obstacle resolution feedback system. The system employs insertion of hybridized elements to the existing designs of Adaptive Ground Collision Avoidance Systems and Midair Collision Avoidance Systems along with a newly design module, the obstacle avoidance dispatcher and resolver, to provide a coherent obstacle resolution. The system is capable of filtering data produced by the hybrid ground collision avoidance module and the hybrid air collision avoidance module, inserting evaluating solution status and command directives before routing avoidance data to hybrid modules for validation. The dispatcher and resolver module determines the final obstacle resolution to generate avoidance control guidance and appropriate warnings clearly indicated obstacle situation and obstacle avoidance maneuvers to the flight crew.

Abstract: An aircraft system for reducing the airspeed of an aircraft as it passes through a preselected altitude includes an automatic throttle system including a computer, a device for inputting a preselected altitude and a preselected airspeed into the computer. An altimeter provides the current altitude of the aircraft and an aircraft instrument provides the current air speed and the vertical speed of the aircraft. The computer in response to the current altitude and vertical speed of the aircraft generates a signal to retard the throttles when the current altitude, the current air speed of the aircraft is equal to 2 times the vertical speed plus a preselected altitude.

Abstract: An improved method for correlating between targets in an air traffic control system. A methods or systems according to the invention compare selected components of a first target report to the components of a second target report, produce a confidence level on each component comparison, and determine whether to declare the targets similar based on the confidence level on each component compared. The first and second target reports may include ADS-B target reports and TIS target reports. The individual components of the reports may be range, bearing, track angle, and relative altitude. The methods or systems may use a fuzzy logic probability model to produce a continuous confidence level on each component comparison.

Abstract: A method for detecting an inaccurate barometric pressure adjustment setting on a barometric altimeter is described. The method includes receiving a barometric corrected altitude from the altimeter, receiving an altitude from a global positioning satellite (GPS) system, comparing the barometric corrected altitude with the altitude received from the GPS system, actuating an alarm if the altitudes differ by an amount larger than a threshold value, the threshold value being dependent upon one or more of the received altitudes.

Abstract: The ground proximity warning system and method provide a number of alerts based upon a substantially reduced list of input parameters relative to a conventional ground proximity warning system and method. The ground proximity warning system and method generally constructs alert envelopes and generates alerts if the upcoming terrain or other obstacles pierce the alert envelopes. The ground proximity warning system and method can also generate alerts if the aircraft has an excessive descent rate at a relatively low altitude and if the aircraft descends immediately following takeoff in a similar fashion to Mode 1 and Mode 3 alerts. Further, the ground proximity warning system and method can provide altitude call outs at predefined altitudes above a target runway and can provide alerts if the aircraft appears to be landing short of a runway.

Abstract: A display control device, having a processor structured for receiving terrain elevation information and samples of current position and altitude above ground data; and one or more algorithms resident on the processor for generating, as a function of the current position and altitude above ground data, one or more display control signals for causing a display device to display, in a monochromatic scale graduated as a function of terrain elevation relative to mean sea level, a strategic portion of the terrain elevation information extending between a minimum elevation of the strategic portion of the terrain elevation information and a pre-selected strategic altitude threshold less than the altitude above ground data.

Abstract: Disclosed is a portable gas alarm device easy to be fabricated as a small-sized one handy to carry and high in convenience for use. The portable gas alarm device comprises a gas alarm device body having a casing flat in whole and a fitting member provided on the casing to fit it to the human body. The gas alarm device body has a control circuit board extending to the direction of the flat plane of the casing, a display mechanism is arranged in a central area on the front surface side of the control circuit board, a gas sensor and an alarm buzzer are arranged on the right and left sides of the display mechanism, and a battery fitting chamber is provided on the back surface side of the circuit board. A vibration generator for alarm may be provided in the gas alarm device body. The fitting member may be one suitable for use in fitting the gas alarm device body to a person's wrist or a person's wear.

Abstract: An integrated cabin pressure control system valve that uses a dual, redundant channel electronic control unit for both control of the valve and to supply alarm, indication, and control signals to the aircraft's avionics system. Each channel in the electronic control unit includes an instrumentation and control circuit that uses multiple, dissimilar sensors and signals for warnings, indications, and controls. This configuration reduces the likelihood for a common mode failure that could result in a postulated gradual decompression without indication event.

Abstract: A system and method for determining the vertical integrity of an altitude component of an aircraft navigational signal through the use of a receiver-autonomous vertical integrity monitoring (RAVIM) algorithm. The system and methods also provide timely warning to vehicle operators if the integrity of the signal is unacceptable or unknown. The system and methods are capable of determining the vertical integrity of an incoming signal without relying upon data embedded within the incoming signal itself. In addition, the system and methods of the present invention provide vertical integrity to vehicle operators in instances, such as when the specific aircraft navigational signal is not operating, when the specific aircraft navigational signal is not available in a particular region, or when an aircraft is operating outside the geographic area covered by the specific aircraft navigational signal system.

Abstract: A terrain-awareness system (TAS) provides LOOK-AHEAD/LOOK-DOWN as well as LOOK-UP terrain advisory and warning indications to the pilot of an aircraft of a hazardous flight condition. The TAS includes an airport data base as well as a terrain data base that is structured to provide various resolutions depending on the topography of the particular geographic area of interest. Navigational data from a satellite-based navigational system, such as a global positioning system (GPS), is used to provide a LOOK-AHEAD/LOOK-DOWN and LOOK-UP terrain advisory and terrain warning indications based upon the current position and projected flight path of the aircraft. Since the terrain advisory and the warning signals are a function of the flight path of the aircraft, nuisance warnings are minimized.

Abstract: The present invention provides several apparatus, methods, and computer program products for generating a terrain clearance floor envelope for use in a ground proximity warning system. In one embodiment, the present invention includes a processor that defines a terrain clearance floor envelope having at least two boundaries. In this embodiment, the processor defines at least one of the boundaries based on a runway position quality factor, an altitude data quality factor, and an aircraft position quality factor. Using these factors, the processor of the present invention can more precisely define the boundaries of the envelope about the selected runway. Further, the processor of the present invention does not unnecessarily increase the region between the envelope and runway where no ground proximity alarms are generated.

Abstract: A method and system for braking aircraft landing gear wheels after initialization of landing gear retraction. The system includes monitors, controlling components, measurement components, a fault recording memory, fault annunciation components, wheel braking system and brakes. The monitors monitor speed of the landing gear wheels and landing gear position. The control component generates braking instructions based on the monitored speed of the wheels and position of the landing gear.

Abstract: A device for enhancing altitude awareness in an avionics display is disclosed. The device includes an altitude indicator that displays a current altitude on the avionics display. A scrolling display of altitude levels is displayed with the altitude indicator on the avionics display. The scrolling display includes a plurality of scaled numbers that represent predetermined intervals of altitude levels surrounding the current altitude. The scrolling display also includes a non-numeric graphic construct that is displayed adjacent the plurality of scaled numbers. The graphic construct has first and second substantially mirror-image portions that are positioned on first and second opposing sides of the plurality of scaled numbers. A controller causes the altitude indicator to display the current altitude on the avionics display.

Abstract: A display system having a display screen for graphical display of data, a graphics processor for receiving data from at least a terrain data base and data from a weather radar and for converting the received data into a single data stream to provide an input data stream to the display screen. The single display displays the weather data on one portion of the display screen and displays the terrain data on a second portion of the display screen. The weather data is displayed as a two-dimensional graphic and the terrain data is displayed as a three-dimensional graphic, thus providing a user with the necessary flight information while keeping processing resources to a reasonable level. The terrain data is displayed as an out the window display graphic, and the weather data and the terrain data displays are scaled such that the displays are dimensionally juxtaposed to allow rapid recognition of the data by a user of the display system.

Abstract: The present invention provides several apparatus, methods, and computer program products for generating a terrain clearance floor envelope for use in a ground proximity warning system. In one embodiment, the present invention includes a processor that defines a terrain clearance floor envelope having at least two boundaries. In this embodiment, the processor defines at least one of the boundaries based on a runway position quality factor, an altitude data quality factor, and an aircraft position quality factor. Using these factors, the processor of the present invention can more precisely define the boundaries of the envelope about the selected runway. Further, the processor of the present invention does not unnecessarily increase the region between the envelope and runway where no ground proximity alarms are generated.

Abstract: A method of determining an altitude of a flying object. A Blanchard altitude of a flying object is computed. A non-Blanchard reference altitude and a trajectory of the flying object are measured and input to a Kalman filter. In the Kalman filter, the non-Blanchard reference altitude and the trajectory are processed to derive a radius of jet stream curvature. A gradient wind correction factor is then computed as a function of the radius of jet stream curvature. The Blanchard altitude is then corrected in response to the gradient wind correction factor.

Abstract: A system for monitoring an aircraft receives navigation signals and deriving a position vector therefrom and also receives an input representative of altitude of the aircraft above ground level. The system samples the position vector at a selected sample rate and outputs a succession of samples of the position vector, the sample rate depending on whether the altitude of the aircraft above ground level is less than a predetermined value. Data packets that contain respective samples of the position vector are transmitted to a ground-based receiving station. The ground-based receiving station may calculate secondary data.

Abstract: A terrain awareness system (TAS) provides LOOK-AHEAD/LOOK-DOWN as well as LOOK-UP terrain advisory and warning indications to the pilot of an aircraft of a hazardous flight condition. The TAS includes an airport data base as well as terrain data base that is structured to provide various resolutions depending on the topography of the particular geographic area of interest. Navigational data from a satellite-based navigational system, such as a global positioning system (GPS), is used to provide a LOOK-AHEAD/LOOK-DOWN and LOOK-UP terrain advisory and terrain warning indications based upon the current position and projected flight path of the aircraft. Since the terrain advisory and the warning signals are a function of the flight path of the aircraft, nuisance warnings are minimized.

Abstract: An apparatus, method and computer program product for suppressing an alert generated by a terrain awareness system rotary wing aircraft of potentially hazardous proximity to terrain also reduces nuisance warnings and provides a terrain display consistent with the unique performance capabilities of such aircraft.

Abstract: A display system having a display screen for graphical display of data, a graphics processor for receiving data from at least a terrain data base and data from a weather radar and for converting the received data into a single data stream to provide an input data stream to the display screen. The single display displays the weather data on one portion of the display screen and displays the terrain data on a second portion of the display screen. The weather data is displayed as a two-dimensional graphic and the terrain data is displayed as a three-dimensional graphic, thus providing a user with the necessary flight information while keeping processing resources to a reasonable level. The terrain data is displayed as an out the window display graphic, and the weather data and the terrain data displays are scaled such that the displays are dimensionally juxtaposed to allow rapid recognition of the data by a user of the display system.

Abstract: A terrain awareness system (TAS) provides LOOK-AHEAD/LOOK-DOWN as well as LOOK-UP terrain advisory and warning indications to the pilot of an aircraft of a hazardous flight condition. The TAS includes an airport data base as well as a terrain data base that is structured to provide various resolutions depending on the topography of the particular geographic area of interest. Navigational data from a satellite-based navigational system, such as a global positioning system (GPS), is used to provide a LOOK-AHEAD/LOOK-DOWN and LOOK-UP terrain advisory and terrain warning indications based upon the current position and projected flight path of the aircraft. Since the terrain advisory and the warning signals are a function of the flight path of the aircraft, nuisance warnings are minimized.

Abstract: Methods and apparatus are provided for generating a vertical situational image of a vehicle. The apparatus for generating a vertical situational image of the vehicle is comprised of an input device configured to receive flight plan data of the vehicle and a situational display configured to produce the vertical situational image from the flight plan data. The apparatus for generating a vertical situational image of the vehicle is further comprised of a processing device that is configured to receive the flight plan data from the input device, generate a first segment having a first slope in a first viewable range of the vertical situational image from the flight plan data and determine the first segment in a second viewable range of the vertical situational image.

Abstract: An apparatus, method and computer program product has a first terrain awareness mode and a second terrain awareness mode selectable by the pilot.

Abstract: A terrain avoidance system, method and computer program product for reducing nuisance alarms. The system includes a geometric altitude component, first and second vertical safety margin generators, and an alert component.

Abstract: A portable pressure measuring apparatus detects a designated altitude by sensing an outside atmospheric pressure. An A/D converter generates pressure data corresponding to the outside pressure. Pressure data corresponding to a designated altitude is stored in a memory, and the pressure data generated by the A/D converter is compared with the stored pressure data. The designated altitude may be set to any value through a manually-operated input switch and converted into pressure data. Alternatively, the designated altitude may be set as the altitude at which the apparatus is positioned by converting pressure data generated by the A/D converter at that altitude into a corresponding altitude.

Abstract: A method and apparatus for automatically providing advisories to pilots in a monitored airspace comprises monitoring weather conditions and air traffic in an airspace and then generating and broadcasting advisories over a radio channel in response to relevant air traffic conditions. Advisory lengths are sized based on the volume of communications on the common traffic advisory frequency. An airspace model, made up of a multitude of constantly updated records, is used to keep track of important flight information and weather conditions. A monitoring CPU, accessing the airspace model, creates the advisory messages based upon hazard criteria, guidelines, airport procedures and other relevant air traffic data.

Abstract: An improved method for correlating between targets in an air traffic control system. A methods or systems according to the invention compare selected components of a first target report to the components of a second target report, produce a confidence level on each component comparison, and determine whether to declare the targets similar based on the confidence level on each component compared. The first and second target reports may include ADS-B target reports and TIS target reports. The individual components of the reports may be range, bearing, track angle, and relative altitude. The methods or systems may use a fuzzy logic probability model to produce a continuous confidence level on each component comparison.

Abstract: Includes means for monitoring the position and behavior of air traffic in the vicinity of the aircraft and generating a warning or avoidance signal for air traffic predicted to be on a collision course. The apparatus also includes means for monitoring the position and behavior of the aircraft relative to terrain in the vicinity of the aircraft flight path to generate a warning or avoidance signal for terrain features predicted to provide a collision threat. Means are provided for receiving the traffic warning signals and terrain warning signals comparing the signals and generating a combined warning or advisory signal which indicates an action for the aircraft which avoids both air traffic and terrain collisions.

Abstract: A conditional TAWS algorithm, system and method for providing advanced warnings of potential hazard situations which could result from changes in heading and vertical speed.

Abstract: In a ground proximity warning system for an aircraft, a signal representing clearance of the aircraft from the underlying terrain is produced from a sea level related altitude signal and a terrain database in addition to the radio altitude signal of the aircraft's radio altimeter. An indication of reasonableness of the aircraft radio altitude signal is formed jointly responsive to the aircraft radio altitude signal and the terrain clearance signal.

Abstract: A Terrain Following Apparatus for a vehicle such as an aircraft includes means (1) for effecting autonomous following of terrain by the vehicle, a control device (2), operable by a person operating the vehicle, to engage and disengage the means (1), a Terrain Referenced Navigation system (3) operable to provide navigation data for the vehicle, and validation means (4) for validating the integrity of the navigation data to provide when the integrity of the navigation data is validated for engagement of the autonomous Terrain Following means (1) by the device (2) and when the integrity of the navigation data is invalidated, for preventing operation of the means (1) when the control device (2) is operated.

Abstract: An ongoing driving habit monitoring system used by insurance companies to more accurately determine the driving habits of their policyholders or authorized drivers to more accurately determine their risk of loss. The system uses a monitoring device located in the insured party's motor vehicle. Each monitoring device is coupled to a GPS receiver, that provides physical location information, and to a wireless modem capable of connecting to a wireless communication network. The system also includes a central computer connected to a wide area network that is able to continuously or intermittently receive movement information from the monitoring device as it travels in a specific region covered by the wireless communication network. The central computer uses a driving monitoring software program and several ancillary databases containing roadway information for a region, route information, and traffic pattern information.

Abstract: A ground proximity warning system, method and computer program product are provided that controllably alter the base width of the alert envelope in order to accommodate uncertainties associated with the current position of the aircraft. In one embodiment, the ground proximity warning system, method and computer program product controllably alter the base width of the alert envelope depending upon an error value, i.e., an uncertainty, associated with the current position of the aircraft. Since the error value associated with the current position of the aircraft is largely dependent upon the type of navigation equipment onboard the aircraft, the ground proximity warning system, method and computer program product of another embodiment controllably alter the base width of the alert envelope depending upon the type of navigation equipment that provides the current position of the aircraft.

Abstract: A working memory contains a local altimetric map defining an altitude envelope of the terrain in the vicinity of the aircraft. A vertical limit path of the aircraft is established, on the basis of status indications and selected flight parameters, in the vertical surface containing the axis of its path. A first comparison is undertaken between this vertical limit path and the corresponding part of the altitude envelope, so as to determine a hazard of a vertical collision with the ground, and an alarm can be established according to the result of this first comparison. A lateral limit path of the aircraft on one side of the vertical of the flight path is also established on the basis of the status indications and selected parameters. A second comparison is made between this lateral limit path and the corresponding part of the altitude envelope.