Everyone asks: Does it matter which engine the pilot starts first?

It varies from one aircraft type to another, and most airlines have procedures for the start order but on a twin-engine aircraft it's more commonly the No 2 engine, on the right side of the aircraft, that gets fired up first.

One reason is that this is usually the engine that supplies power to the hydraulic system for the brakes, and the parking brake needs to be released before pushback can start. Another reason is that the No 2 engine is on the opposite side from the air bridge, which is a safety factor, and away from the ramp services agent's access to the headset plug and towbar pin.

There are also some occasions when the pilot will have to start an engine before boarding is completed, and the No 2 engine is the obvious choice since the aircraft will be boarding on the left. Boeing's twin-engine aircraft are fairly consistent in this regard, but on an A330 and A340, Airbus recommends starting engine No 1 first because that engine pressurises the parking brake. On an A320, the recommendation is for starting engine two first.