Underexposure help

Today I got these photos rejected for being underexposed as the common rejection. Do the screeners mean that the sky/background was underexposed or the aircraft? To fix them, I adjusted the levels a tiny bit and added some brightness. I realize sometimes that I learn more of repairing my rejected photos. Any tips on fixing them? Thanks.

http://web01.jetphotos.net/viewreject_b.php?id=1706079
http://web01.jetphotos.net/viewreject_b.php?id=1706082
http://web01.jetphotos.net/viewreject_b.php?id=1706083
http://web01.jetphotos.net/viewreject_b.php?id=1706085
http://web01.jetphotos.net/viewreject_b.php?id=1706091

I opened a couple of them in PS, and they do look a little dark based on the histograms. A couple of them, like the Delta shot, are tricky, because on the bright end, you are just about blowing out the upper fuselage, but the underside is dark. You might try adjusting the center slider on the levels adjustment, or play with the curves - that's something I'm still working at getting a handle on.

I can see jaggies on the titles of your Jet Airways shot, as well as on the top side of the blue cheat line where it curves up toward the tail. The World MD-11 looks high in the frame. I think the main problem you are having with "dark" rejections has to do with the undersides, and I think a little mid-level adjustment with the curves or levels will help you out.

I think this is the one thing I'm actually good at...

As Moose said, you'll need to play with the Levels or Curves; I got decent results by dragging the center slider in Levels to the left.

Also, in either Curves or Levels, there are three eyedroppers that let you select areas of white, 50% gray, and black. 50% gray is the most important to get right; if you get white or black wrong, you'll be able to tell immediately :). Use a Threshold Layer to determine where the white, 50% gray, and black areas are, but in a landing shot, they will be in the following places:

White: Where the sun hits the fuselage
Black: The tires or the shadow inside the wheel well
50% gray: usually near the top of the shadow on the bottom of the fuselage. Play with it until the colors look right

Once you use the eyedroppers, any adjustments you make in Curves or Levels will be more effective. I only had to drag the middle slider a little to the left to get your photo looking better; it looked a bit washed out, but I suspect you'd get better results starting with the original image.

Also, if you shoot in RAW, you can get a ton of control over the color in Adobe Camera Raw when you first open the image.