SA2 is correct.....
goes 6K, 5.5K, 5K, 4.5K, 4K, 3.5K, 3K, 2.5K, 2K, 1.5K, 1K, 1000, 800, 600, 400, 200, 0
1.5k is 1500 to 1999
1K is 1000 to 1499
1000 is 801 to 1000
that is how I have always understood it
still in all, my point was understanding the difference in alt measurement vs icon measurement and turn radius measurement.
when people in game say enemy is 5k alt, some are calling out what the enemy's icon says when infact he is 3 times higher when you encounter him
then some says "I was only 1K or 1.5K below you climbing to you", well that means I had a 3,000 ft alt advantage on you or more....I was just trying to offer a description of the difference so people can understand why or how things happen or are able to happen....
as SA2 pointed out, when you get down to the 1K icon the distance is easier to close.....yes to a degree, but sometimes it looks easy but when talking vertical it is not as easy to close at it appears...