Delta727 From , joined Dec 1969, posts, RR: Posted (14 years 10 months 5 days 4 hours ago) and read 1034 times:
Just an idea...why not do away with the traditional radar and replace it with aircraft-reported GPS positions and the usual transponder information? Based on my understanding of radar, wouldn't this allow for more frequent updates of a/c position, alt, etc. on the radar screen, and get rid of squawk codes altogether?
Leo-ERJ From , joined Dec 1969, posts, RR:
Reply 1, posted (14 years 10 months 5 days 3 hours ago) and read 1023 times:
First of all, most airports are equipped with this kind of technology. What you might be referring to is the use of higher tech ATMS systems such as the STARS systems being implemented in the major airports. In doing this, the expenses are always high and it takes a while to rewire the entire system of an ATC.
What most airports are installing are equipments such as a differential GPS with the use of relative receivers, and the so-called Satellite landing system. This ensures a large satellite coverage that can enhance the control tower's control over the range of airborne planes on a specifies area. With its higher precision it can precisely determine approach reference and aircraft distances so aircrafts can fly closer to each other and still be in a safe range. This will be useful for crowded airports where the use of many parallel runways can facilitate simultaneous approach of different aircrafts and still perform a safe landing but in a quicker timespan.
The squawk codes work as a refernce to the ATC. The tower needs relative position information from the transponder in order to maintain a log and control of the a/c both on air and ground. What this system does is it impoves the time laose and gives a more accurate data to the tower. This is not mainstream yet so most airports keep on with the current available technology. However, the use of radar will not be extiguinshed from use where it can specify things that is not determined by the new SLS system. So even though the equipment improves, the old stuff is still important.
Jim From United States of America, joined Jul 1999, 455 posts, RR: 1
Reply 2, posted (14 years 10 months 5 days ago) and read 1013 times:
As I learned in class yesterday, the GPS is only accurate to about 100 m (95% of the tiime) for non-military use. Thus, it may be good for nav fixes where there is no Navigation Radios available (Oceanic and Polar flights), it is not acurrate enough for landing. The VOR / DME and GS / LOC system now in place can fix the position of an aircraft right at the centerline 1000' from the end of the runway EVERYTIME!
Microwave systems sound nice, but they are just too expensive in this economy of cutting Gov't spending.