Vectors are most often used to get an aircraft onto their course or an approach procedure. You may vector aircraft in controlled airspace for:
Separation
Safety
Noise abatement
Operational advantage
Confidence maneuver
When a pilot requests
In Class G (uncontrolled) airspace, vector upon pilot request as an additional service.
Vectors should be used above the MVA or the minimum IFR altitude except as authorized for radar approaches, radar departures, special VFR, VFR operations, or by paragraph 5-6-3, Vectors Below Minimum Altitude.
Aircraft may not be vectored off an Obstacle Departure Procedure (ODP), or issued an altitude lower than published altitude on an ODP, until at or above the MVA/MIA, at which time the ODP is canceled.
Radar facilities may vector aircraft below the MVA/MIA, provided:
No prominent obstacles are within 10 NM of the departure end of runway (DER).
Aircraft must be allowed an uninterrupted climb to meet the MVA/MIA within 10 NM of the DER.
Specify the direction of turn (if appropriate) and the magnetic heading to fly.
TURN LEFT/RIGHT HEADING (degrees).
FLY HEADING (degrees).
FLY PRESENT HEADING.
DEPART (fix) HEADING (degrees).
You may also specify just the degrees of the turn:
TURN (number of degrees) DEGREES LEFT/RIGHT.
When initiating a vector, advise the pilot of the purpose, and if appropriate, what to expect when radar navigational guidance is terminated.
VECTOR TO (fix or airway).
VECTOR TO INTERCEPT (name of NAVAID) (specified) RADIAL.
VECTOR FOR SPACING.