I do believe it says in those sites someplace, but it was in 1970 that Maynard took the altitude record.
*just went back and looked - the one link didn't make it, with all Maynards FAI records...duplicated the one before. Here it is:
Maynard's records - some broken, some still standing...
And all the current FAI records:
Current Records
If the first one doesn't work, due to asp, you can click on Current Records, and at the right, see what other records the holders have....
And it's possible that AMA may have something somewhere on it, but the true sanctioning body is the FAI, and they are the only ones that can verify and accept or deny an international record attempt, I believe. So AMA, while somewhat involved, would possibly not have anything other than a record of it. I do know that Walt Good was active at the time, with Maynard Hill, and collaborated with him on several record attempts.
Of course, I'm not
that old, just have always been interested in the history of our hobby...just a high-schooler when the record was won.
All the guys around me were still flying yo-yo's, back then, was years later when I got into the r/c.
R