Aviation Father's Day gifts
Buying for a father has one advantage over every other case on this site, and most people never use it. You have access to the photographs.
Somewhere there is a shoebox, a hard drive, or an album nobody has opened since it was filled. If he flew, there are pictures of aircraft in it. If he took the family to airshows, there are pictures of aircraft in it. Nobody else buying him a present has that, and it is worth more than any amount of browsing.
What to look for
Not the best photograph. The one with him in the story: the aircraft he trained on, the type he worked around, the one from the summer everybody remembers. A slightly imperfect picture of the right aeroplane beats a beautiful picture of one he feels nothing about, every time.
Old family photographs are often small, soft or scanned badly, and that matters less here than you would expect. The blueprint and poster treatments redraw the shape rather than enlarging the pixels, so they carry a middling source to a bigger size than a straight photographic print would. Turning plane photos into wall art covers how to judge what you have found.
If the box turns up nothing
Then use the place. Ask him, or ask your mother, where he flew from or which airfield he went to most. The airport code print is built from four typed lines and needs no picture, which makes it the reliable fallback rather than the second-best option.
And the timing is worth a thought. This is made when you order it, so a week's margin turns a stressful order into an ordinary one.
If you already know exactly which aircraft, aircraft gifts is the direct route. Otherwise the gift covers the whole stage.
Next — On the wall

Paper →
Paper, unframed, in five sizes. It is the cheapest way in and, for two of the five art styles, it is also the best surface we have.
Also in the gift
The briefing
Questions, answered
The only photo I can find is an old print. Can I use it?
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Scan it as large as your scanner allows and try it. Old prints often surprise people. If the file is too small for the size you want, the site will not offer that size, and the blueprint or poster treatments handle a weak original far better than a straight photographic print does.
What if he flew something I cannot identify?
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It does not matter. Nothing here needs the aircraft named. You upload the photograph and the picture is made from what is in it, so an unidentified aeroplane works exactly as well as a labelled one.