I think the problem is that these pics are quite a way below the acceptable standard. Generally, if people ask for comments on shots that are borderline, or just not quite up to it, then people are more ready to offer hints and advice - along the lines of "if you try doing this, maybe it will be accepted".
You also set yourself up for criticism by your subject line - "some of my best work". Now, I'm sure you didn't mean it this way, but it comes across as being slightly arrogant - and is just the sort of thing to incite people to write negatively about your photos.
But here goes with the sort of comments I think you were after:
The photos ARE quite a way below the current acceptable standards for being added to the database, so I don't think there's any sort of editing you could do to these scans that would improve them enough to get in.
The Southwest 737 isn't centred in the frame. If you crop off some of the blue space on the left side it will look slightly better. You also have a black border at the top, and what looks like a hint of a white edge at the bottom. You MUST remove all such borders and edges before uploading to A.N. because your pic will almost certainly get rejected otherwise, regardless of the quality. This pic is the best of the 3 quality-wise, but the colours do appear to be a little pale and insubstantial, and there's a little bit of grain (particularly evident in the darker areas). The pic as a whole also isn't sharp enough.
The ATA nose close up is a nice framing, but again, it's not sharp enough, and the grain really kills it. I think from looking at this shot that you are using a film that's just too fast - and that's what's causing the grain. Another thing is that because you are on the wrong side for the sun, it makes things even worse. Grain shows up much more clearly on dark areas that light ones - and for this kind of shot, it's really a good idea to be on the sunny side. If you are, you can get a pic that really shows off the fine detail of the fuselage.
As for the other ATA shot, this is the poorest of the 3. Taking its minor points first, again you're on the wrong side (but you knew that already), and I don't particularly like the crop - this is just a personal thing, but you have cropped (or the framing of the original pic is such) that almost the whole horizontal stabliser is missing at the back. I prefer a little more room here, so the edge of the pic is not quite so close to the tail (other people may disagree however). More seriously, again not sharp, and mega grain. In fact, it looks as if this pic has been enlarged from the original, because there is so much loss of detail. Did you crop in to a pic that had a lot of empty space around the aircraft, and then resize it up to get a pic of the right size to upload?
I wonder what sort of camera/lens and film you are using? If you have a 35mm SLR, then you really should be using ISO 100 film in order to get the best results. This will drastically reduce the amount of grain, while improving the colours in your shots at the same time. As long as you shoot in sunny conditions, you will still be able to get a fast enough shutter speed (1/250 or 1/500) to freeze the action. If you're using a zoom compact however, then frankly you will struggle to take these kinds of pics, because the lens won't be fast enough to allow you to use ISO 100 film. If you're having to use ISO 400 or even ISO 800 (The dreaded Kodak Gold "Zoom") then your pics are going to be grainy and there's nothing you can do about it.