Okay, after a quick proof read I think I might try to actually answer your question! <img border="0" title="" alt="[Smile]" src="smile.gif" /> <img border="0" title="" alt="[Smile]" src="smile.gif" /> . .You know you're on the ground because the ground safety relay kicks the solenoid in the landing gear handle, so that you can't select gear-up on the ground. You also get the auto-spoilers moving the spoiler lever all the way back to the fully deployed ground spoiler position, and that makes a quite noticeable noise.. .There's also a LOT of other little things that happen that tells the plane that it's on the ground, but those two above really tell the pilot that the main wheels are on the ground.. .It takes a while to get a good landing technique in the thing, because you can actually land the plane too softly - The landing gear on the 747 sits at quite an angle with the wheels off the ground, and so when you touch down the un-tilting of the wheel trucks tells the logic circuitry that the plane is on the ground.. .But!. .You don't actually have to un-tilt the trucks much at all, so it's possible to just get them touching the runway, the plane says 'Okay, I'm on the ground so I'll throw the spoilers up all the way', and when that happens a fair chunk of the wing stops making lift, and so the plane drops a few feet onto the runway.. .Hence the phrase occasionally heard on the flight deck, "Well, the first one was nice!" <img border="0" title="" alt="[Smile]" src="smile.gif" /> . .On a landing with the sink rate too high, you naturally feel the plane 'thump' onto the ground. Boeing have kindly built the 747 so you can land it at max landing weight (~285 tonnes) and not flare it at all, and it will suffer no damage.. .On a good landing, the sink rate is such that you can hardly feel the plane touch down at all, and the only feeling you get is as the wheels spin up.