Flying level above a curved earth

[WWhiskey]

Just a really weird (and possibly dumb) question that popped into my mind this morning. If an aircraft is flying along at 15,000ft level flight continuesly, will that aircraft eventually start to climb higher in altitude due to the Earth being curved and NOT level? Or, are aircraft attitude indicators designed to keep you flying level according to the curvature of the Earth?


My mind comes up with some wacky questions 

was it, at any time, on a treadmill?

[mtnman]

Off topic a bit, but this subject makes me think of another physics question that haunts me.  Water in a lake more or less "self-levels".  What about water in a river?  Is its surface "sloped" downhill/downstream?  It can't really "self-level" like water in a lake, unless it undulates or "stair-steps"...  I realize it's constantly moving, but in a slow-moving stream I'd think it would level out quicker than it would flow downstream.  What about a lake with an entry and exit stream?  Does the water slope downhill in the top stream, level out in the pond, and then slope downhill again as it exits the pond?

Anyway, sorry for the hijack- just another "head-ache" question...

[ghi]

Off topic a bit, but this subject makes me think of another physics question that haunts me.  Water in a lake more or less "self-levels".  What about water in a river?  Is its surface "sloped" downhill/downstream?  It can't really "self-level" like water in a lake, unless it undulates or "stair-steps"...  I realize it's constantly moving, but in a slow-moving stream I'd think it would level out quicker than it would flow downstream.  What about a lake with an entry and exit stream?  Does the water slope downhill in the top stream, level out in the pond, and then slope downhill again as it exits the pond?

Anyway, sorry for the hijack- just another "head-ache" question...

When i first navigate through Panama Canal,working on cruise ships, i read in daily informative flayer about the Canal .I was surprised to find out the level of the Pacific waters are higher than Atlantic  in that zone. If  would have been built like the Suez Canal without locks, the water from Pacific would flow into Atlantic.

[moot]

Waters of the oceans arent nearly level. Look it up on an atlas, it's pretty dramatic.