Just as I thought, "Attack of the Hawkmen" uses footage from the great WW1 flick, "Aces High". Sometimes the shots are direct lifts and other times they have been embellished with added elements or effects. (For some time, I thought some clips might have come from "The Blue Max" but apparently not.)
All the shots of the German anti-aircraft guns, some close-ups of the planes taking damage from enemy fire and ALL the aerial views of the terrain below during the 1st photo-reconnaisance flight are borrowed. (In one aerial terrain shot, 2 planes were added alongside Harry & Indy's Sopwith Camel.) In a handful of shots with flying/crashing planes you can clearly see the British RAF roundel insignia instead of the French one!
instead of this
There are also many parallels with the 2 stories such as, Indy's initial arrival at the airfield, the photo-reconaissance missions, Richtofen's insistance to the army that the prisoner is his, etc. Not to mention the tagline on this poster
is similar to Indy's experience. "High above the trenches 14 days is a long life..." (Plus the star, a young Peter Firth, plays Indy's ally Stefan, in "Istanbul/Masks of Evil"!)
"Aces High" is an excellent film and is really worth checking out. Another fine companion piece to the Yound Indy tales. I saw it on TV one night many, many years ago but it's now available on DVD.
P.S. Both movies use the song, "The Bold Aviator Lay Dying"!