Pinching a good idea from the past is no uncommon thing in media, as most mainstream cinema and music goes to show.
Nor is it necessarily even a bad thing. People only really tend to have an issue with such historical pilfering when the new stuff turns out to be markedly inferior
Fly THIS! isn't a bad casual puzzler by any means. It simply fails to match up to its relatively ancient source of inspiration.
Fly THIS! lifts its premise from the decade-old Flight Control. This was the original line-drawing smash hit, which had you drawing out flight plans for a bunch of aircraft buzzing around a busy airport, bringing them safely in to land whilst avoiding mid-air collisions.
You're doing the same basic thing here, but with more rigidly defined bite-sized levels and a few more rule variations. Levels are more zoomed out here, with multiple airports to shuffle your planes in between.
There's a colour-coded element at play, too, whereby passengers need dropping off at the like-coloured airport.
On the plus side, there's more variation as a result. New level layouts are introduced at a constant rate, with fresh twists like vison-impairing clouds or strong wind currents.
Conversely, you never slip into that part-blissful part-stressed state that Flight Control and its better imitators could invoke. It feels a lot lighter and, well, more forgettable.
The fact that you can no longer get Flight Control on the App Store (and haven't been able to for ages) might make such comparisons unhelpful. But those who were there back in the day will be disappointed that Fly THIS! doesn't do more to reinvigorate this once-beloved genre.
Those new to this whole line drawing thing, meanwhile, will probably wonder what all the fuss was about.