To ga

TO GA is a switch or setting activated on the autothrottle of an autopilot of a modern aircraft. It has two modes, one is the TO (takeoff) mode. Once an aircraft has lined up, the pilots can select the TO GA switch and the engines will increase to approximately 50% power (this is done to ensure that an uneven application of power does not happen when the take off starts) and then to their computed take off power. There are common misconceptions that all aircraft pilots push forward the throttles to full power to take off. This is untrue. Modern aircraft flight management computers will determine the power needed by the engines to take off based on a number of factors such as runway length, wind speed, temperature, and most importantly the weight of the aircraft. The advantage of having such a system is the ability to reduce wear and tear on the engines by only using as much power as is actually required to ensure the aircraft reaches a safe take off speed. The most obvious example of such a take off would be in a commuter jet such as an Embraer 145. On this aircraft, it is common to use this method of take off by using the whole runway available and not to use 100% engine available power. Passengers often comment on how long a small jet like this takes to reach take off speed, but it is all part of the flight management system to ensure minimum wear on the engines.

The GA switch is used when a landing is taking place. If a pilot finds that they are unable to land at the last minute by activating this switch everything is taken care of. The power will increase to maximum on the engines, the aircraft will automatically pull up to a climb attitude, and the autopilot will route the aircraft into the designated missed approach pattern that the airport insists aircraft must fly if missing a landing. The GA switch can be used even when touched down if, for example, there is a sudden blocking of the runway towards the end, the switch can be activated and the aircraft will lift off again into the missed approach pattern.

The switch is the same for both TO and GA modes, the autopilot & throttles knows what stage of flight you are in by how the autopilot is set. Usually on approach to land the autopilot will be set to approach mode on the autopilot therefore if you press the switch it will activate the GA mode.