To use the CLC, two knobs controlled "radial" and "distance. Unlike a standard VOR instrument, a full-scale deflection on the CLC was 2 miles, whether you were 1 mile from the station or 50 miles from the station. Creating a direct route could shave off substantial mileage compared to victor airways, which rely on routes between NAVAIDs.
Initially, GPS was only available for government and military use. But by , a full satellite constellation became operational and was opened to public use. For an aircraft to get a 3D location, the GPS receiver must get a reliable signal from 4 satellites simultaneously. Flight Management Systems FMS , which are typically found on business and airline jets, allow you to enter a series of waypoints and instrument procedures that define a flight route.
If waypoints and procedures are included in the navigation database, the computer calculates the distances and courses between all waypoints in the route.
Many FMS systems in large aircraft are linked to an Inertial Navigation Unit often times called an Inertial Reference System, or IRS , which is comprised of lasers and gyros that determine aircraft flight path, altitude, and attitude. And that's not the only extra source of information for an FMS. If one form of navigation becomes unreliable, backup navigation aids can be used for continuous position information. This is presented as guidance information on the flight deck display.
In vertical navigation VNAV mode, vertical guidance is provided, as well as horizontal guidance in some installations. A WP is selected at a point where the descent begins, and another WP is selected where the descent ends. RNAV2 can be used for en-route navigation. RNP systems are certified on a case by case basis. Generally, the aircraft must be certified to a specific service level, and the crew must be trained in how to use it. RNP has three service levels that are standardized in the United States, depending on how accurately the system fixes the aircraft position.
They are RNP0. To use any system in the IFR environment, it must be certified for specific segments of a flight, i. One major requirement for certification of systems is a form of self-testing to ensure that the navigation signal being used is accurate. RAIM stands for receiver autonomous integrity monitoring.
It means that the receiver is capable of detecting when the signal is compromised for some reason. The process of computing the integrity of the signal is relatively straight-forward. For RAIM to work, the receiver needs to see at least one more satellite than it would typically need.
For a three-dimensional position fix, it would need to be receiving five GNSS satellites. It repeats this process, recalculating the position each time. The positions should be the same. If it determines that one position does not match the others, it will notify the pilot that the signal is unreliable. Not only should a pilot be alerted to the problem, but a pilot also needs to know in advance.
The pilot does not want to begin the approach only then to be told during a critical phase of flight that RAIM has become unavailable. For this reason, receivers usually have a calculator built in that can forecast the availability of RAIM at a future place and time.
PBN Handbook No. Categories : Flight Technical Enhancing Safety.
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