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I was wondering what is the regular range of Approach VHF radios used by ATC (normally 50W)? And what about En Route VHF radios (usually 100 or 250W)?

Pondlife
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Nick
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    Are you asking about frequency ranges or the distance at which the radios can effectively be received. The first is a hard range the second will depend on altitude and terrain. – Dave Jul 25 '18 at 16:30

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VHF radios are line-of-sight, and typically the range is limited not by the transmit power but by terrain and the aircraft's horizon. PPL students are taught a rule of thumb: the range in nautical miles is the square root of 1.5 times the aircraft's altitude in feet. This makes your range roughly 40 nm at 1000 ft, 90 nm at 5000 ft, and 120 nm at 10000 ft.

En-route stations intended to be used over a wide area will typically use several transmitters on high ground many miles apart, to ensure reception over their whole operating area. Even so, low-level flying can put you into a blind spot between transmitters.

Dan Hulme
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  • I have not found the Approach radios to be receivable at that range. That would imply Boston (MA) Approach would be receivable to nearly Albany, NY. I know that at 6,500ft they are not. Their service areas are also much smaller. Going westward, Boston hands off to NY Center, then Bradley Approach, then Albany Approach, unless you climb higher to stay in NY Center's domain for longer. Flying down to the Cape, 91nm, an even shorter distance (about 10 miles), one changes frequency several times as well, and the main Boston radio cannot be picked up that far away. No terrain in between either. – CrossRoads Jul 25 '18 at 18:17