I live at 20 Km from MAD,I was wondering,at what altitude are the airplanes that far out of the airport?
I know there won-t be an exact altitude, since MD-80's are higher than a A340.I want an aproximation(i.e 3000-6000 ft)
It depends where you are in relationship to the airport, and which runway they are using. In general they use r/w 33.
If you are to the north, then can be usually you will be in the region of 12,000-14000 ft.
If you are to the south you could be anything from 4-7000 ft. It can vary greatly depending on if you do the complete arrival or whether you get more direct radar vectors.
If the aircraft have to fly 20 km to reach you, then they'll pass you maybe three minutes after takeoff? I'm guessing 2500-3000 ft per minute is a typical rate of climb for not-too-heavy departures-- so they'll be around 8000 ft above airport elevation, if they've been climbing the whole time.
If they're right overhead, compare their size with the moon or the sun, which are maybe 110 times as far away as their diameter. So if an MD80's length equals the sun/moon's diameter (and you're looking at it at 90 degrees) then its 5 km away-- and so on.
I live about 20 miles west of EWR, and the planes that are departing that fly over my house are usually in the 10000 to 12000 feet range. I get mostly approach aircraft, though, and they are all usually at around 5000 feet when they go over my house.