Lol, how turbulent was that 737-800s approach? Looks like the right wing was moving down while you were tracking the left side of the fuselage/wing. Couple of suggestions on taking aircraft approach shots:
Sun at your back (very important since you're gonna be looking at sky) (as you know)
Low light setting is gonna best so morning or evening is gonna be the key time to do it
Landing shots are cool, but the most drama is aircraft on takeoff, JUST after they lift off
Cloudy days are pretty hard to shoot, light is rough on the aircraft and most blend in with the sky since they're white.
Unless you're shooting prop aircraft, use the highest shutter speed you can without losing any detail
Here are some of my approach shots:
<a href="http://www.flickr.com/photos/25174230@N03/2419766850/" title="Challenger 300 by flyinhawaiian071, on Flickr"><img src="http://farm3.static.flickr.com/2409/2419766850_4454160339_b.jpg" width="1024" height="684" alt="Challenger 300" /></a>