Vertical resolution and/or vertical accuracy of terrain elevation data near an aircraft runway is adjusted by obtaining local terrain data, yielding a first elevation value for a query location. A processor receptive of the first elevation value computes plane equations based on a predetermined standard model adapted to geometrically conform to the aircraft runway, yielding a second elevation value for the query location. The processor selectively uses the first and second elevation values to generate an adjusted elevation value that is supplied to a terrain avoidance and warning system.

To provide a fuel cell system configured to increase fuel cell performance even at high altitude. A fuel cell system for air vehicles, wherein the fuel cell system comprises: a fuel cell, an oxidant gas system for supplying oxidant gas to the fuel cell, an altitude sensor, and a controller; wherein the oxidant gas system comprises an air compressor and a bypass flow path bypassing the fuel cell; wherein the bypass flow path comprises a bypass valve; and wherein, when the controller detects an altitude increase measured by the altitude sensor, the controller increases a rotational speed of the air compressor, and the controller increases an opening degree of the bypass valve.

An unmanned aerial vehicle (UAV) includes a vehicle body, one or more propulsion units coupled to the vehicle body, and one or more processors operably coupled to the one or more propulsion units. The one or more processors are configured to receive one or more original altitude restrictions for the UAV, receive elevation information for an area the UAV is operating in or will operate in, determine one or more modified altitude restrictions based on the one or more original altitude restrictions and the elevation information, compare the one or more modified altitude restrictions with a legal altitude restriction to determine whether the one or more modified altitude restrictions are legally compliant, and if so, control the one or more propulsion units to cause the UAV to comply with the one or more modified altitude restrictions while operating in the area.

A method and a system for establishing a route of an unmanned aerial vehicle are provided. The method includes identifying an object from surface scanning data and shaping a space, which facilitates autonomous flight, as a layer, collecting surface image data for a flight path from the shaped layer, and analyzing a change in image resolution according to a distance from the object through the collected surface image data and extracting an altitude value on a flight route.

Techniques are provided for vision-based altitude estimation using one or more platform mounted cameras. An embodiment includes generating projected ground imagery of imagery provided by cameras of the platform, the projection based on a hypothesized altitude. The method also includes obtaining reference ground imagery based on the location of the platform, the location based on platform navigation data. The method further includes registering the projected ground imagery to the reference ground imagery and generating a match score associated with the registration. The method further includes selecting the hypothesized altitude as the estimated altitude based on the match score (e.g., if the match score exceeds a threshold value or is maximized over a set of hypothesized altitudes. The method may further include otherwise adjusting the hypothesized altitude and repeating the altitude estimation process based on the adjusted hypothesized altitude to search for an improved estimated altitude based on the match score.

Systems and methods are disclosed that include fault monitoring for a radar altitude device. Fault monitoring is performed by receiving first altitude data from the radar altitude device, receiving second altitude data from a second altitude measuring device, receiving terrain data from a terrain database, determining a fault condition threshold adaptively based on the terrain data, determining whether the radar altitude device is exhibiting a fault condition based on the first and second altitude data and the fault condition threshold, and outputting an indication of the fault condition based on the determination of whether the radar altitude device is exhibiting the fault condition.

Systems and methods are disclosed that include fault monitoring for a radar altitude device. Fault monitoring is performed by receiving first altitude data from the radar altitude device, receiving second altitude data from a second altitude measuring device, receiving terrain data from a terrain database, determining a fault condition threshold adaptively based on the terrain data, determining whether the radar altitude device is exhibiting a fault condition based on the first and second altitude data and the fault condition threshold, and outputting an indication of the fault condition based on the determination of whether the radar altitude device is exhibiting the fault condition.

A laser measuring instrument comprises a light emitter, a driver, a scanning unit, a light receiving signal processing module for detecting a reciprocating time per pulsed light of a distance measuring light and performing a distance measurement, and a timing generating circuit for issuing a timing signal, wherein the timing generating circuit is configured to issue a timing signal for making the light emitter pulse-emit in a short cycle and a timing signal for pausing a light emission, the driver is configured to make the light emitter pulse-emit according to the timing signals, a light emission time interval in the short cycle is set such that a measuring point is multiply irradiated with the pulsed light by two or more times within a time when the pulsed light passes the measuring point, and the light receiving signal processing module is configured to integrate acquired light receiving signals and to carry out the distance measurement.

Methods, apparatuses, and systems for predicting radio altimeter failures are provided. An example method may include determining a first plurality of altitude values associated with a first radio altimeter, determining a second plurality of altitude values associated with a second radio altimeter, calculating a first level feature based at least in part on the first plurality of altitude values and the second plurality of altitude values, and determining a radio altimeter failure indicator based at least in part on the first level feature.

A synthetic radio altimeter system is provided. At least one sensor is used to generate sensor data that is used at least to determine a then current vehicle location. At least one controller is configured to determine an elevation of terrain under a vehicle based on the determined then current location of the vehicle and terrain information in the terrain database. The at least one controller is further configured to determine a height of the vehicle above terrain based at least in part on the determined elevation of terrain under the vehicle and the sensor data. The at least one controller further configured to augment the determined height of the vehicle above terrain with at least in part navigation database information when the vehicle is near one of a travel path origin and a travel path destination. The height above terrain may also be augmented based on a navigation radio.