[vathra]

Yes, it is interesting story. In my opinion, one of the top 10 escape stories from Yugoslavia. And more than 2,500 allied airmen evaded from Yugoslavia, so it was very tough competition.

One of the aviators wrote a book about it:
Talmadge Callison, "Hit the silk"
Unfortunately, it is old and I could not find it on Amazon, etc.
It seems circulation was small.

In Escape statement is generally what Boris already wrote. After capture in Hungary, Americans were transferred to Tulln, Luftwaffe base (not regular prison). They were approached by German Luftwaffe officers who were in custody due to overstay from leave, and frightened of soviet advance. Germans organized escape and transport to airfield. Allied airmen were supposed to be used as their pass when they reach Italy.