Hi zorroa, thanks for the compiment.
I just saw your message on flickr, yes sydney airport. The A380 in the above post, and the one you commented on in flickr was at the car park for the old control tower. Great light in the arvo. The 737 in the second pic in my above post was from the other side of the airport just near the big container shipping terminal. There is a little car park you can park at and there is a walk out observation point. It's a good spot at first light for a few hours. You can even park at the boat ramp just up the road and still get some shots, but this smaller carpark is slightly closer. Check it out on google earth and you'll see what I mean.
I live a few hours away at Lake Macquarie so I don't get down there very often but always drop by camera in hand when I get the chance.
You don't need a huge lens for the classic side shots as this shot below shows, this image (which is a bit noisy for some reason) was at 100mm with next to no crop, from the car park for the old control tower. In fact if you walk along the beach and up to that fence you see next to the runway at left of image, the A380/747 tips are pretty much overhead when they are taxiing past. Some guys take a small ladder for clean shots, which from what I have been told is ok by security as long as you are not up against the fence You can actually see someone in black standing there in the pic. Obviously for the landing shots etc, 400mm never goes astray, but from these spots, you'll certainly get close to them!
Edit: just found out the name of the one near the shipping terminal. Look for port botany viewing platform on Google Earth, and the old control tower is just after you go under the runway heading west it's off to the left off General holmes Drive. Don't take the M5 lane but as that lane splits off it's only a couple of hundred meters past. In the afternoon I was surprised to see how many plane photogs that were there, must have been about 10 the last time I went.
hope it OK if i ask whis camera your using for these photos? i am going to also upgrade from my T2i .......