The shadow of the Islandsflug plane is not the closer black asphalt. It is a little further, and if you open the large photo and look carefully enough, you'll see the perfect shadow of the whole airplane.
The 320 that crashed was not supposed to do a low pass. Have a look at the video: it has the gear down, and a landing attitude (nose up). The low passes (exhibition ones) must be with the gears up, in order to avoid wheel contact with the ground, and for granting an optical effect. Otherwise, from afar, people would think the low pass was a "touch&go" instead. Also, low passes are flown horizontally, for pilots and tails "health".
The 320 crash was a misprogrammed autoland.
Discussions on "low passes" have been held here. The "secret", if any, for doing them is the "ground effect". The wings lift the plane, but below a minimum altitude, the airflow under the wing gets "compressed" between the wing and the ground, thus increasing lift substantially.
The next time you fly, pay attention to something: a very short while after the main gear lifts, a slight sensation of "descent" can be felt. It is the critical moment when, increasing the distance from the asphalt, the "ground effect" is lost, resulting in a slightly lesser sustemptation. As far as I understood, this is a critical moment strongly related to Vr (therefore Vr being always higher than stall speed, if I am not mistaken), and taken care of, because below a certain speed, the airplane can get airborne without being able to keep up there and fall down again. Maybe a pilot could enlighten us better about this very special moment. In that other forum, someone wrote that the airplane would be able to fly a little sooner than it really does, but it is "kept" on the ground until the lift generated by clear speed is higher than the lift generated by the combination of speed and ground effect.
This is also why Formula 1 cars carry inverted wings: they would not fly because they do not have the proper propulsion, but they would lift from ground, due to speed alone.
The Europeans will remember the Ford Sierra (predecessor of today's Ford Mondeo in Europe/Contour in USA), the 1986 model SR Cosworth, 2door version, and the huge aileron mounted on the trunk, (the 4door's aileron was quite smaller). By then I was a mechanic at the biggest Ford workshop in BCN, and drove the first one in the whole Spain. OK. Without that aileron, the Sierra Cosworth was unable to go above 180 km/h (115mph) safely because the rear wheels were loosing the capacity of solidly transmitting 220 HP to the ground...
Back to the topic, and not being too sure if I made my explanation clear enough, this ground effect is the reason why flying so low is safe: the ground effect prevents the airplane from falling lower than it is.
Back in time, there was also a post about "ekranoplanes"
See that the "thing" is not touching the water, in spite of what, the water below is waving and being sprayed. See also how small the "wings" are.
wich are boats that "sail" at 500 km/h (315 mph) or "fly" at few feet from the water
, the truth being that they do not do one thing neither the other: they take advantage of ground effect.
Hope I helped...