After a couple of ideas for lenses.
Wanting to get into landscape photography
And also after a longer lens for aviation.
Currently have the following
Sigma 17-50
Canon 50mm
Canon 55-250 is
A really nice landscape lens option for your APS-C body is the Canon EF-S 10-18mm F4.5-5.6 IS STM Lens
I bought this even though I had (and still have) the EF-S 10-22mm f/3.5-4.5 USM.
The latter was too heavy as a walkabout lens so even though the 10-18 is lighter, slower and somewhat plastic, it's IQ is very good. FWIW, the price is very reasonable. The fact it has Image Stabilisation is a bonus but stuck on a tripod it's easier to turn it off, useful on handheld shots.
This review is useful.
View: https://youtu.be/D4o4oMf3Av
The 10-22 has no IS but again not really an issue for landscape work, but it is a weighty beast! It's also over £400 so if cash is a problem then
second hand is an option. I got mine off the forum and it does a great job.
If tou wat a fixed rime wide angle and happy to go manual then one of the Samyang range may prove interesting. I have the 14mm version which use mostly for star trails.
I tried thr Sigma 10-20 WA DC lenses but neither was as good as the Canon 10-22.
As for airshows etc I use an EF 70-200 L f/4 with a 1.4x TC
Bit of a handful but will do. If I was going to go further then I eould be lookung at the Sigma 150-600 Sport for it's weather sealing. It is heavy!
Good luck
Steve