Transiting Controlled Airspace

Once you are assigned an altitude in controlled airspace, maintain that altitude until instructed otherwise. Report when you are leaving one altitude and arriving at another:
"OE-CMV, leaving flight level nine thousand five hundred, climbing flight level one-one thousand."
"OE-CMV, level flight level one-one thousand."
Never deviate from your assigned altitude without permission, even if you encounter weather or turbulence. If you must deviate, immediately inform ATC of your reason and request a new altitude:
"Vienna Approach, OE-CMV, request immediate descent, encountering moderate turbulence."
ATC will either clear you to a new altitude or inform you that the deviation is approved:
"OE-CMV, descend flight level one-zero thousand, due to traffic."
Continue communicating with ATC until you leave controlled airspace. When you reach the boundary of controlled airspace and are about to exit, inform ATC:
"Vienna Approach, OE-CMV, leaving controlled airspace."
ATC will acknowledge and provide you with a frequency for the facility covering the uncontrolled airspace:
"OE-CMV, good day. Contact Brno Information on one-two-one decimal five-zero."

Transiting Controlled Airspace

Vienna Approach · OE-CMV

PILOT: Vienna Approach, OE-CMV, Cessna one-seven-two, forty-five miles west of Vienna, flight level nine thousand, destination Brno.
VIENNA: OE-CMV, Vienna Approach, good morning, climb flight level one-one thousand, squawk two-three-zero-zero.
PILOT: Climb flight level one-one thousand, squawk two-three-zero-zero, OE-CMV.
PILOT: OE-CMV, leaving flight level nine thousand, climbing flight level one-one thousand.
VIENNA: OE-CMV, ROGER. [5 minutes later]
PILOT: OE-CMV, level flight level one-one thousand.
VIENNA: OE-CMV, ROGER. Traffic information: Airbus three-twenty, flight level one-zero thousand, ten miles ahead, northbound.
PILOT: OE-CMV, NEGATIVE CONTACT, will continue to look.
VIENNA: OE-CMV, ROGER. Continue current flight level.
PILOT: OE-CMV, position report, abeam Vienna VOR, flight level one-one thousand, VFR estimating Brno one-five-thirty.
VIENNA: OE-CMV, position acknowledged. Contact Brno Information on one-two-one decimal five-zero.
PILOT: Contact Brno one-two-one decimal five-zero, OE-CMV.