The diagram alongside shows a basic 4 channel transmitter. There are 2 sticks, each of which controls 2 of the 4 primary flight controls. Each stick is gimballed so that it can be moved in both axes. The up and down movement controls either elevator or throttle, and the left and right movement controls either the ailerons or rudder. The sticks are sprung so that they return to the centre position when released, with the exception of the throttle control which has a ratchet mechanism so that it will stay at the throttle position selected.

Which stick operates which control is determined by the mode of the transmitter. These are:

Mode 1
This has pitch and roll control on separate sticks, with roll control on the right stick, and pitch control on the left. The perceived advantage of this layout is the separation of pitch and roll control onto different sticks, which is considered to give more precise control over both as operation of one cannot inadvertently change the other.

Mode 2
This has pitch and roll control on the same stick, in a manner similar to the way the primary controls of an full size aircraft operate. The other stick has the yaw and throttle controls. (see primary flight controls for an explanation of these terms) The perceived advantage is that as pitch and roll are the primary means of controlling the models flight path, having them on the same stick makes it easier to co-ordinate the two.

Mode 3
This control stick configuration has the rudder and elevator being controlled by the right stick while the left stick controls the ailerons (roll) and throttle.

Glider guiders can ignore the reference to throttle and perhaps think of it as spoiler operation.

Which should you choose?
The quick answer to that one is to choose the same as your instructor. Because of the mental adjustment required to fly on different modes, most people, once they have learnt to fly, stick with the one mode and in any club one mode of operation will be prevalent. Because of this no instructor is likely to teach you to fly using a different mode to the one he or she normally uses, so you should ensure that any radio equipment you buy operates on the same mode as your instructor. Most radio sets are capable of being easily swapped between A and B, but you should check before purchase whether the particular set you are buying is on the desired mode, or if not, that it can be changed easily.