I have had the same issue numerous times. In my opinion, yes, a 16 year old can be taught to be a quiet riding pony. it sounds like he thinks you are a preditor when you go to catch him and that's why he runs. one you get him and he realizes you're not, he's fine. he hasn't picked up on it yet because flight has been so instilled in him.
Even if you don't ride him, i agree that he should be catchable.
Spend time with him. I mean hours. If you're not afraid of him, sit in a chair or something in the field and read a book. Or sit on the fence, that's generally safer in the beginning. don't try to catch him, don't even try to touch him. become a regular figure in his field. Horses are curious by nature and once he realizes you're not doing anything, he'll come to investigate you.
No matter how many steps he takes towards you, change NOTHING. make him touch you first before you dream of touching him. this will take a while, i promise, but it will work. when he does start coming to you, make being caught the most fun part of the day. Give him treats, pat him, then go away. do it a few times a day if you can. make him understand that every time you come into his home, you're not going to work him, you just want to spend time with him. then start to change it up. Sometimes take him in and work him, sometimes just play with him.
He will be far more accepting of you when he knows who you are. The last mare i did this with actually kicked her owner when she was trying to catch her. it took me two months and now, if you whistle inside the barn, she will nicker and run to the fence waiting for you.
be patient and keep us updated! good luck!