How far out of an airport to get its ATIS, Most of the time, I get ILS clearance from controller giving me Rwy in use. I would like to get ATIS prior to descend so I can organize my radios for ILS landing or GPS.
If I remember correctly from my ATPL's you take the square root of the ac height in feet + the square of the ground station height in feet. This should give an indication of the range of the ATIS.
FL230 airfield elevation 140 feet.
I could however be totally wrong! It's been a while
Square roots and decimals...keep it simple! Some of us are pilots here. 😂
General rule is..it depends. If you are low altitude and a mountain is your way, you may not get the signal until you are ontop of the airport.
Otherwise, you can expect to get it as much as 100 miles out at high altitudes. It is all based on line of site.
Of course, that's in the real world. It all depends on what the programmers did. I wish that they had put HIWAS on stations that are designated to have it. Now, that would be nice.