A missed approach must be executed when one of the following conditions occurs: 

1. Arrival at the missed approach point and the runway environment is not yet in sight

2. Arrival at DA/DH on the glide slope with the runway environment not yet in sight;

3. Anytime a pilot determines a safe landing is not possible 

4. When circling-to-land visual contact is lost; 

5. When instructed by ATC.

In non-precision procedures, the pilot determines the MAP by timing from the FAF when the approach aid is well away from the airport, by a fix or NAVAID when the navigation facility is located on the field, or by waypoints as defined by GPS or VOR/DME RNAV. If no final approach fix is depicted, the MAP is at the airport (NAVAID) on the airport.

For a precision approach (ILS), the MAP is at the Decision Altitude/Height (DA/DH). 

Missed approach procedures published on an approach chart are not followed when ATC has assigned alternate missed approach instructions.

Protected obstacle clearance areas for missed approaches are predicated on the assumption that the missed approach is initiated at the Decision Altitude/Height (DA/DH) or at the Missed Approach Point, and not lower than the minimum descent altitude (MDA), then climbing 200 feet/NM or greater. Reasonable buffers are provided for normal maneuvers. However, no consideration is given to an abnormally early turn—Initiating a go-around after passing the published in MAP may result in total loss of obstacle clearance. Therefore when an early missed approach is executed, pilot should (unless otherwise cleared by ATC) fly the IAP as specified on the approach plate to the missed approach point at or above the MDA or DA/DH, before executing a turning maneuver.

Basic Missed Approach Procedures:

1. Full throttle

2. Trim nose up 7.5 degrees

3. Flaps up after establishing a positive rate of  climb