The purpose of the range check is to make sure the Strong radio signal from transmitter to receiver , so that you can fly your rc airplane at a normal distance away from you without it going out of radio range. If your plane does go out of range, then you lose all control.
Perform a range check with a MHz radio system thus:
Switch on the transmitter then the receiver, and with the transmitter antenna fully collapsed (i.e. down), walk backwards away from the airplane for 30 paces or so. As you walk away from the plane, keep moving the control surface sticks of the Tx (not the motor!) and closely watch the respective control surfaces of the airplane.
If you only get a short distance away and the surfaces start ‘twitching’ or not responding properly to your stick movements, do not fly. Check the batteries of the radio gear, they may need replacing – low batteries in the transmitter drastically reduce the radio range. Also check for loose connections to the receiver etc., and also the condition of the antenna(s).
If the batteries and connections are OK but the control surfaces still don’t respond properly, then other people may be using your frequency nearby. Again, do not fly if this is the case. Interference is a big killer of rc airplanes, and you need to be sure that your frequency is clear before you get airborne.
An rc airplane range check with a 2.4GHz radio system is slightly different, in that the antenna cannot be collapsed. You will have to refer to your radio instruction manual to see the correct range check procedure for your exact radio, as different manufacturers use different methods of activating the range check mode in a 2.4GHz radio.
Whichever method is involved, a 2.4GHz radio in range check mode sends out the signals with a reduced voltage, thus producing a weaker signal.
The rest of the check is performed in the same way as explained above.
Regardless of whether you have a MHz or 2.4GHz system, do not fly your plane if you see that control surface response becomes unreliable before you reach 30 paces or so away from the plane. You need to identify and rectify before you fly!
If your plane isn’t behaving itself on the ground, then it’s not going to improve in the air!
Always take a few minutes to perform these rc airplane pre-flight checks before you commence your flying session. Get into the habit of pre-flighting your plane every time; the checks take just a couple of minutes to do and will save you the grief of a crashed airplane, if something is amiss.