Commercial aviation has long relied on radar technology for navigation, but slowly, it's being replaced by GPS. This article outlines the course of the change in the US, as well as the advantages that GPS brings over the old radar system.
Status Quo: Radar Technology
The US's FAA, Federal Aviation Administration, has long relied on radar technology for commercial aviation, along with the rest of the world. It has worked well enough on a small scale, and until recently, there really have not been any alternatives.
However, the current system is having a more and more difficult time coping with the high traffic. It's not an issue of just manpower, but also the technology: radar takes time, and isn't particularly accurate, and for a pilot landing at a jam-packed airport in crowded airspace, this leads to some logistical issues.
This is important, especially as air traffic grows along with population, globalization and movement out of the recession. Everyone is familiar with those inconvenient and late flights: the idea behind this upgrade is to make the logistics of air traffic as efficient as possible, and adaptation to unpredictable weather conditions as smooth as can be.
GPS Upgrade: Advantages
GPS has a number of advantages to offer everyone in the aviation business. Pilots will be able to take advantage the more accurate traffic and navigation data that GPS technology will afford them, especially in places that are far away from radar control. Indeed, it will allow for greater independence of the pilot from air traffic control agents, lessening their labor load while also making the whole process safer precisely because they will be less harried.
Such a broadcast would also include detailed meteorological and aeronautical data to the pilots in a broadcast known as a FIS-B, or Flight Information Service-Broadcast. At current, much of the data is given in a non-standard format, and often navigating unfamiliar airports can be difficult for pilots.
GPS technology is already widely used by private aviation enthusiasts due to its reliability, though there are some caveats to its legality.
Infrastructure & Hardware
Of course, implementing such a system in airports and airplanes will require some substantial changes to the current infrastructure, a good part of why the upgrade hasn't been made already.
The main upgrade will come by way of a system known as ADS-B, Automatic Dependent Surveillance-Broadcast. Less esoterically, this translates to a broadcast for pilots, which goes onto display screen that functions in real time, not just radar updates, which shows the exact positions of all nearby airplanes in the area as well as important local features such as mountain ranges and airports.
The transition will take time: it would be unrealistic to upgrade all commercial airplanes with ADS-B at the same time. So, ADS-B is designed to also include those airplanes that are located with older radar technology, using an interface program called TIS-B, or Traffic Information Service-Broadcast.
Coming to an airport near you?
This technology has already received some testing in Alaska and in the Ohio River Valley with some commercial air transport planes, though not on a wide scale quite yet.
The FAA hopes to have this used throughout the US, or at least, throughout the National Airspace System, by 2013. Radar is still intended to be used as a backup technology even after implementation of ADS-B. The total cost of the NextGen plan is estimated by the FAA to be somewhere between 15 and 22 billion dollars through 2025. Pretty steep, but for a multi-trillion dollar industry that really needs the upgrade, it's a small price to pay.
For more information, check out this excellent CNET article series on the topic, including many pictures of the new displays and detailed explanations for how it works on the pilot-end. The New York Times also has an excellent article on the new technology.