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These two transmitters have been connected with a trainer cable. The instructor pilot uses the master transmitter, in this case the Hitec Neon at the left. The student pilot uses the slave unit, in this case thr Hitec Eclipse at the right. You can see the cable in this photo. Bob’s finger is pointing to the trainer switch mounted on the top of the Neon (master) transmitter. Operating this switch allows the instructor to take back control of the model immediately at any time.

A similar photo appeared in Chapter 7 of the “From the Ground Up” series. Don Abramson (R) is about to hand launch the AeroCraft “Pogo” ARF model. Don holds the master transmitter in his left hand with the antenna fully extended because it is the one broadcasting the signal to the Pogo. At left, student Jay Federman holds the Hitec Eclipse transmitter with the antenna retracted because it does not have to send out any signal. Don gains control of the flight by virtue of the trainer switch on the top of his transmitter.

Q-35: I noted in Chapter 10 of the "From the Ground Up" series that you wrote about using a trainer cable between two RC transmitters when instructing a new pilot. I do this all the time and hate to tell you that you got your reference backward. Would you care to comment on that?

A-35: Well, I hate admit it, but I did get the story backward. If you first refer to my Chapter 7 article in the "From the Ground Up" series, "The POGO ARF’s First Flights" (September 2003 Model Aviation, page 71), I showed the two transmitters connected with a trainer cable. Then, in the upper right photo you see instructor pilot Don Abramson holding the Hitec Neon three-channel RC transmitter while getting ready to hand launch the POGO. Student pilot Jay Federman is on the left

Don is holding the master transmitter with the antenna fully extended. This is the transmitter that is broadcasting the signal to the Pogo. Jay is holding a Hitec Eclipse transmitter with its antenna collapsed or retracted. That transmitter, connected to Don's transmitter by the trainer cable, does not broadcast a signal. With a flip of a switch on the master transmitter, Don can take over the control of the Pogo at any time should Jay get into difficulties.

Unfortunately, several months went by. While preparing Chapter 10 on "Advanced RC Systems"  which appeared in the February 2004 Model Aviation (p. 46), I stated that student Jay was holding the Neon unit serving as master transmitter, while as instructor, I held the Eclipse transmitter. That sequence is backwards and be advised that the September 2003 article is correct. I’m sure reading the RC manufacturer's instructions provided with the trainer cable will help you figure this out quickly. However, I did want to set the record straight.

This same reader also mentioned the importance of identical control input settings on both transmitters (student's and instructor's). If you use dual rate control on only one transmitter, as you switch control to the other transmitter, that control input would disappear. It is very important that you run a careful preflight check at the start of your flying session to verify that all controls on both transmitters are set identically. I might add that since I was using the Hitec Eclipse, which is a computer transmitter, I picked an unused memory position and then called up "RESET" which returned all the controls to their factory default positions (control throws and trim at neutral or zero positions).

One last comment! Jack Albrecht of Airtronics recently informed me that the company offers a “trainer box” which is just a box containing two control-stick assemblies, reversing switches, and an encoder circuit board. No power is necessary because the encoder gets its power through the trainer cable. The student holds this trainer control box when flying. This item is Airtronics' catalog No. VG400-TR and sells for only $39.95. This is a real bargain and will certainly extend the use of trainer cables once the word gets out. My thanks to you, Jack!

—Bob Aberle