Well, that's where inertia comes to play. While flying, you can feel as if you were stationary high up above, even though you're not.
But isn't that an entirely different thing seeing as when we are flying we are contained by the plane. But getting back on point, how does inertia act on the oceans to hold them in place as it were, I can't quite grasp this point? You seem to be saying it's part gravity part inertia that prevents water from falling into the sky and beyond, my question still is how can a certain point in the centre of the Earth have that much influence over the elements? Obviously I'm not being very scientific here, I'm just curious to know if it's possible to get an explanation which I can understand and accept.
Well, the oceans are contained by the Earth in the same way. What's the difference?
This is stupid - it's not about "containment" it's about forces.
That nice Isaac Newton guy helpfully told us all we need to know. "An object in motion remains in motion unless acted on by an external force". So when the Earth and all of it's Oceans are speeding along together - there is no external force that would cause them to start to move at different speeds and thereby "separate".
There are external forces on the Earth (the gravity of the sun and moon, for example) - but those act equally on the Earth and the Water...but not PERFECTLY.
Because the water nearest the moon is closer to the moon than the rest of the earth, it gets SLIGHTLY more gravitational pull - and that's what causes the tides.
But without air resistance or friction, there is no reason for the water (and the air, and you and me) to become detached.
Now - the airplane analogy is a TERRIBLE one. If you were to sit on the wing of a plane - you'd be swept away in an instant because the force of air resistance on your body is not being counteracted by the engines of the airplane. So the airplane carries on flying - but you get swept away to the rear. Inside the airplane, the structure of the fuselage protects you from all of that fast moving air - so, as per Sir Isaac Newton - you and the plane carry on moving at the same speed.
There is nothing strange going on here. That same, simple, universal law of motion applies to absolutely everything in the universe.
The argument about the tides is a VERY good one though - the water of the earth is sloshing about around our planet because of the difference between the moon's gravity on one side and the other - and also because the Earth and Moon are both spinning around a common point. The result of this is that when the moon is overhead, the waters of the earth try very hard to rush towards the moon - but the Earth's gravity is far stronger - so instead of rushing into the sky - it merely bulges a bit in that direction. On the opposite side of the earth, the moon's gravity is a little less - but the centrifugal force generated by the Earth and Moon orbiting each other is enough to cause a second high tide when the moon is below our feet.
This is why there are two tides each day - it is (in a sense) the waters of the earth being pulled or flung away from it. Fortunately, gravity is high enough to prevent them from moving more than a few feet in that direction before being allowed to fall back to their normal height a few hours later.
The ideas of Flat Earth theory do not explain why there are two tides each day...which is a point you might want to consider.