Weve all performed a go-around at one point or another, certainly in training. Many of them are begun at some altitude close to the runway, when it becomes obvious a go-around is preferable to rolling off the end of the runway. In most of the airplanes we fly, going around can be a relatively simple matter. It is, however, a high-workload maneuver and can require some finesse.
For example, many airplanes dont climb well with full, landing flaps applied. At the same time, retracting all the flaps at once can drastically and dangerously affect lift being produced by the wings. Pitch trim is another consideration and can result in a sharp pitch up when set for landing and full power is applied. Often, its better to do these things in stages: add enough power to arrest the descent, clean up the flaps, add more power, retract the landing gear, re-set the trim as a climb is established, then add full power. The more complicated the airplane, the more things to do, and the more reasons there may be to perform the go-around in the first place.
