The most obvious and well known use of the GNSS system is in the field of Navigation. With the introduction of reliable information from the NavStar GPS, aircraft can now use it fly accurately and safely over terrain and ocean. The GPS can give the aircraft will invaluable position information without the concern that other navigation aids such as VOR/NDB system. These concerns were often linked to the limitations of the system and just how accurate they were. Now with GPS the aircraft can fly more direct tracks which have huge implications of the savings on fuel and time. This makes the aviation industry better.
But just what can the GNSS systems give to the industry. With glass cockpits the GPS can be integrated with maps to provide moving map GPS or with Synthetic vision systems to provide the aircraft with an awareness of terrain even in poor visibility.
The information coupled with other instrument can provide accurate airspeed or other useful information. The systems can be linked with ground users such as ATC and Search and Rescue providing them with position information to help control and find aircraft.
The applications found in iphones and android based phones (example blackberry)to help with GPS reliability
Use of GPS may even on the ground being able to accurately position machinery to remove the human element away from dangerous systems.
The accurate information is used to help auto-land aircraft.
However, there are some disadvantages to the introduction of GPS. One of the main concerns is reliability of the service especially during times of crisis. The ability for the U.S. to turn on Selective Availability has caused many place build DGPS in order to maintain some level of service should GPS become unavailable.
There are also however, some human factor that need to be considered. For example “adverse key-strike properties, load on memory, non-intuitive logic, non-standardization of models, database irregularities, and difficult-to-read displays”1 which comes from the amount of information available and the ability to design ergonomic unit for pilots. Though these problems can be identified be as ergonomic problems, there is still a need to understand the system as a whole to determine what each mode does and what it can offer.
The GNSS systems are very complex in design and sometime implication. The move for approaches into airport towards using GNSS equipment leads to a need to improve the system and its upkeep.
- Technology Improvement
- With older technology the errors during approach where accepted and dealt with by using safety margins and procedures to keep aircraft apart. However, with the increase in accuracy and the need to enter all the reporting points, holds and approaches around the world, there needs to be a system in place to check that these are entered correctly. Even the Garmin database (a very popular GPS Unit) has some missing data, which then adds into question the safety of these devices. Even the slightest error can lead an aircraft off into a wrong position. With all the routes having been developed to accommodate the limitations of older equipment, the GNSS systems need to include all these track plus more if these are to used in conjunction.
- The moving map GPS is a very advance tool compared to navigating using maps. The ability to have the aircraft position laid on top of a map means that the pilot can maintain a very high situational awareness of where they are. However, the basic skills of navigation are still needed, especially in General Aviation. If the moving map was to fail for any reason, there must still be a level of assurance that these pilots could safely navigate themselves to a suit landing spot.
- Situational Awareness
- The is some debate to if the GPS adds to situational awareness. It is clear that this system can prevent a pilot from getting lost, however, this is only the case if the pilot can use the system. The design of current of the user side of GNSSs means that there is a lot of preparation work in order for the unit to be useful. In IFR, the pilot must program the whole flight in which is time consuming and can be difficult. If changes need to be made during this flight, this can take the pilot away from other duties like aviating2.
- Each GNSS system will have it own limitation, including unavailable times because of RAIM, which means that the GPS is unavailable. Without understanding why thes problems occur, then a pilot might get worried if they came across this problem. Also understanding the different system may mean it is possible to switch should one become a problem.
- Trust in aviation is very important and can be very deadly. The list above are all factors in Trust. Too much trust however, in GPS can lead to aircraft flying the wrong way. Garbage In Equals Garbage Out. If too much trust is put into these systems without understanding them or checking that the inputs are correct, the pilots could find themselves in stressful or even dangerous situations as they try to work out whats wrong.
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- HF with GPS