White, the colour of most planes are painted. When looking at a ramp at an airport, the fact is clearly evident. The reason airlines choose this is because of several factors ranging from the cost to operational conditions.
Starting with the cost, an important factor especially if an airline operates with a medium-sized fleet. this color is cheaper than other more striking colors as well as It is also easier to maintain a standard color especially if the lessor companies provides this one to different airlines as a single coat.
As the weight on aircraft in general is one of the most important characteristic, the white color gives the property of lightweight paint, helping this to the overall weight of the plane. Therefore, a light plane translates into fuel savings. Remember a Boeing 747 uses around 90 gallons of paint that weighs about 550 pounds and these savings could be used for carrying baggage or some people.
Maintainability, the versatility of restoring the aircraft. The white needs fewer polishing procedures than other colors, decreasing the periodic maintenance of the paint. The white colour allows to identify dents, cracks, fluid leaks or other defects on planes surfaces, helping see abnormalities quickly in order to repair them. Improving visibility of the aircraft reduces the hazard conditions, this allows others to see the plane and even birds when aircraft is flying, avoiding unexpected collisions or birds strikes.
Another relevant reason is, the white paint on planes reflects the sunlight, so the heat accumulation on plane surfaces is less, as we may know the UV light increases as we climb higher. Thereby reducing the risk and high temperature in cabin helping to the cooling system of the aircraft in fuel savings.