Do they measure an airplane's flight distance in the air or on the ground? ?

That's an interesting question. I guess it depends on the method you are using. Today we mostly fly by the GPS. It measures distance without regard to altitude. However, some methods would include altitude such as DME (which measures slant line distance). I guess I really never gave it a lot of thought. :)

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No. There is no way that an earthquake can directly affect anything that is in the air. The pressure waves created by the movement of the plates involved in the earthquake are transmitted through the rock of the earth's crust. That energy does not get transmitted in any way that is significant into the air, so there is no corresponding pressure wave above ground. With sensitive instruments, you could probably measure some momentary atmospheric pressure changes, but the would be small differences only, and only very close to the ground. The ground and water are essentially incompressible - apply X amount of force at one end, and you feel the same X amount of force everywhere else. That is why hydraulic equipment works. In an open system like the earth, the energy does dissipate as it spreads out. Air, on the other hand is highly compressible, so it is very poor at transmitting energy. A very powerful explosion above ground creates a pressure wave that can and would affect anything that is flying. Explosives with a very high detonation velocity create a visible pressure wave in the atmosphere. That energy can travel upwards of 30,000 feet/second. There are old films of nuclear bomb tests where buildings were erected within the test zone to see the effects of the blast wave - and they are completely destroyed within a large radius of the blast zone. That kind of energy could physically destroy a plane. However - for any kind of energy propagated through the air, the force of the blast wave diminishes quite quickly because the same amount of energy is filling an every increasing volume of space. If you receive X amount of energy from the blast at a certain distance, you would receive only 1/8 of X if you are twice as far away. Even the pressure wave from a nuclear bomb detonation near the ground would have no effect on a plane flying at 30,000 feet altitude.

I know what your asking and yes the true distance traveled is farther than the distance on the ground Just like an object in orbit travels much farther than the circumference of the earth at the surface

The circumference of the earth at the equator is 24,902 miles At 30,000 feet the airplane is roughly 5.6 miles high and it would have to travel 24919.4 miles to Circle the earth at that altitude Or 17.4 miles farther than at sea level

On coast to coast flight there would only be a small difference

The aircraft owners manual lists the range of the airplane in both 'hours of flight duration' and miles it can travel on full tanks of fuel in a no-wind condition. Experienced pilots always rely on 'hours of duration' instead of 'miles' because flights are usually made in conditions of either a headwind or tailwind. For instance, if the airplane is good for five hours duration and it cruises at 100 mph it will travel 500 miles in a no-wind condition before running out of fuel. If it is flying into a 50 mph headwind it will only cover 250 miles across the ground before it runs out and the cockpit 'gets as quiet as a Christian Science Reading Room'. If the pilots' destination was 500 miles away with no other place to land, he/she will fall short of a happy landing by some 250 miles. Bottom line; if the airplane has a duration of five hours, be prepared to land in five hours regardless of actual distance travelled! I'm a 3500 hour flight instructor.

In the Air from one point to another in a straight line

ıSo how can i measure the air distance flown that if i know altitude and Ground distance traveled in nautical mile (Zero wind condt.)??

It's measured from one point to the other, in a straight line.

As the crow flies, in the air. If it's measured on the ground, it''s called a train.

well, since the earth rotates on axis while the plane is in the air, measuring the flight by ground wouldnt be accurate;however, they use both for many reasons:)