Cricri From France, joined Oct 1999, 581 posts, RR: 6 Posted (15 years 6 months 6 days 8 hours ago) and read 2898 times:
Second post, second question
Let's take us the example of a transatlantic flight from Europe to the United States. I know that there are some "holes" where there is a lack of control towers and so the planes communicate each other giving their position on their respective routes. My question is : is there a continuously radar tracking even in the middle of the atlantic? and if yes, civil or military?
Thanks again for your replies.
Apopa From , joined Dec 1969, posts, RR:
Reply 1, posted (15 years 6 months 6 days 6 hours ago) and read 2877 times:
Because of the curvature of the earth, radar range is limited. For a ground based radar at sea level, an aircraft flying at 30,000 feet can be detected at 220 nautical miles at the horizon. Placing the radar on a mountain top would extend this a bit farther, but not much. There is a similar problem with VHF/UHF communications blackout because they are also line of sight systems. In the past HF has been used for over ocean communications because it reflects from the ionosphere; however, this is not always reliable. This has left a great deal of the ocean beyond communications and radar range. Fortunately satelite communications are begining to be used for over water air communications; however, space based radar, except for military operation, is still a long way off.
Best regards - apopa