Only one air traffic control unit must control an aircraft at any given time.
The control of an aircraft must be transferred from one control unit to another at the time the aircraft is estimated to cross the control boundary or at such other point or time agreed upon by the two units.
The transferring unit must forward to the accepting unit any changed flight plan or control data which are pertinent to the transfer.
The accepting unit must notify the transferring unit if it is unable to accept control under the terms specified, or it must specify the changes or conditions required so that the aircraft can be accepted.
The accepting unit must not alter the clearance of an aircraft that has not yet reached the transfer of control point without the prior approval of the transferring unit.
Where nonradar separation minima are being applied, the transfer of air-ground communications with an aircraft must be made 5 minutes before the time at which the aircraft is estimated to reach the boundary unless otherwise agreed to by the control and/or communication units concerned.