The definition of cross country flight changes, depending on the certificate requirements to which you are applying it. If you're logging cross country time for the purposes of a private or commercial, then yes, the distance is 50 nm, with a landing at least 50 nm from your original point of departure. If you read your regulation, however, you'll find that for the ATP, the flight must reach a point at least 50 nm from the point of departure, but doesn't require a landing at a place other than the point of departure. The cross country definition for meeting the experience requirements for the private or commercial differ from the ATP, and yet again if logging time toward meeting Part 135 minimums.

The basic definition of cross country, as defined in 14 CFR 61.1:

Cross-country time means—

(i) Except as provided in paragraphs (ii) through (vi) of this definition, time acquired during flight—

(A) Conducted by a person who holds a pilot certificate;

(B) Conducted in an aircraft;

(C) That includes a landing at a point other than the point of departure; and

(D) That involves the use of dead reckoning, pilotage, electronic navigation aids, radio aids, or other navigation systems to navigate to the landing point.

This basic definition of cross country places no distance requirement. If you're seeking time toward 135 minimums, for example, any flight with a landing other than the point of departure is considered cross country, with no distance requirement. However, for meeting the cross country requirements of the ATP, the cross country definition is:

(vi) For the purpose of meeting the aeronautical experience requirements for an airline transport pilot certificate (except with a rotorcraft category rating), time acquired during a flight—

(A) Conducted in an appropriate aircraft;

(B) That is at least a straight-line distance of more than 50 nautical miles from the original point of departure; and

(C) That involves the use of dead reckoning, pilotage, electronic navigation aids, radio aids, or other navigation systems.

Note that for the ATP, if you reach a point of more than 50 nm during the flight it doesn't matter if you land. If you go to a point at least 50 nm from your original point of departure, orbit for six hours and recover back at your original point of departure, it meets the cross country requirements of the ATP, and you have 6 hours plus the transit time to and from your orbit point.

http://www.faa.gov/about/office_org/...rpretation.pdf

I understand your concern; is flying to a point in space and performing air work for several hours over a given point really "cross country?" The answer is yes, for the purposes of meeting the ATP experience requirements, if you flew at least 50 nm from your point of departure. Another way you could think about it, rather than cruising to your operations area and the working, is conducting the entire flight in slow flight. If you flew at 100 knots instead of 300, for example, the flight would take a lot longer, but would still be cross country. If you did S turns across your course the entire time, it would take longer, but still be cross country. If you stopped occasionally to circle objects of interest enroute ,it's still cross country, even though the flight is taking longer . Likewise, if you fly to your operations area and work traffic, and you're 50 nm from your point of departure, it counts as cross country for meeting the ATP requirements.

You could perform the airwork at any time during the flight; you don't need to go 50 nm away to do it. You could fly 5 miles away, work traffic, then go 50 nm from the point of departure and return; it's still considered cross country if you choose to use it toward the ATP.

What it won't do is meet the cross country requirements for 135 (100 hours XC VFR, or 500 Hours XC for IFR ops), because that does require a landing at a point other than the point of departure. I point this out only to note that the x-c requirements vary with the particular level of certification, and operational application that you're pursuing.

If you're in a rotorcraft, it's 25 nm, rather than 50 nm.