Most helicopter pilots sit in the right seat, but do they have to? It does depend of the type of helicopter, and even if there are some advantages when it comes to the control of the aircraft, there is also a historical reason behind it.
Buttons, radios, instrument knobs, rotor brakes or clutches are usually located on a center console in a side-by-side crew arrangement. The cyclic is positioned so the pilot has to use his right hand to control it, which leave the left hand to control the collective lever. So in flight, it is easier to let go of the collective lever to be able to push the button located in the center console. This is way easier to accomplish while sitting in the right seat, since if the pilot was in the left seat, he would have to reach across himself to get to the center console.
Igor Sikorsky built the R-4, the main purpose of the aircraft was to train student. Due to weight constraint at the time, there was only one collective, situated between the seats. Then, there are two stories explaining why the student would sit on the right seat. First story states that it would be for a better control of the collective, while the other story rather say that Les Morris, test pilot for Sikorsky, was used to sit on the left seat in the VS-300, in which the collective control was on the left side of the seat, and did not want to change seat when he started to teach students how to fly the R-4, so they were trained in the right seat. The students were then used to fly from the right seat, which would explain why the pilots would sit on the right side of the helicopter in the U.S. Army Air Force, Navy, Coast Guard, etc.
However, there would be an advantage to sitting in the left seat while carrying loads underneath the helicopter. Indeed, this would allow the pilot to be able to see the load better than in the right seat, since it is easier to control the collective while leaning to the left.
Do you think helicopter pilots should be in the left seat like a fixed wings aircraft pilot, or should it stays as it is?