I am sure you are aware of this, but there is a plane now able to carry 800 passengers. Would the weight of this plane if it crashed have an disturb the planet maybe like a small comet would? Could it cause a tsunami if it landed in the ocean?
Let's compare the energies of a couple of different phenomena to give us a sense of their scale. A common unit to use for very large energies is a "ton", which is the amount of energy release by one ton of TNT: 4.1 billion joules.
First let's calculate the kinetic energy of the Airbus A380 at it takeoff weight, moving its maximum speed. Check out these specs for the numbers.
The kinetic energy of an object is equal to 1/2 times its mass times its speed squared. For a maximum takeoff weight of 560 tonnes and moving at Mach 0.89 (89% of the speed of sound), the kinetic energy of the Airbus is 2.5 trillion joules, or about 500 tons. The energy that the Airbus would transfer to the ocean if it crashed there is likely less than this (let's hope it never crashes, of course!).
Now, the energy of the nuclear bomb that detonated in Hiroshima during World War II had an energy of 15 kilotons: 30 times greater than the energy of the Airbus that we calculated above.
The energy of the Indian Ocean tsunami on December 26th has been estimated at about 300 megatons, or the equivalent of 23 thousand Hiroshima bombs! Check out this article for details. So, the energy in the tsunami is about a hundred thousand times greater than the maximum airbus energy.
Finally, Near Earth Asteroids, or NEOs, with energies greater than 3 megatons (100 times lower energy than the tsunami) are just able to penetrate the Earth's atmosphere. On the other hand, the KT impact 65 million years ago that is though to have caused the dinosaur extinction had an energy of about 100 million megatons: this is 1/3 of a million times greater than the tsunami energy!
The bottom line is that if the Airbus A380 did crash (and we do hope that it never does!) it will not disturb the planet like a comet impact or cause a tsunami: it doesn't have nearly enough energy.
Checked on July 18, 2015.