Did you know that when Air Traffic Control says "radar contact" it usually isn't?
Did you know that most of the replies from your Mode C transponder are Mode A?
Did you know that as many as 90% of transponder replies are discarded by ATC computers and never appear on any scope?
Did you know that there are thousands of places where a controller can see the transponder on an IFR aircraft but cannot see a fully-functioning transponder on a conflicting VFR aircraft, and there is nothing you or the controller can do about it? Worse yet, did you know that FAA has these places all mapped out, but does not provide the data to pilots or controllers?
Did you know that some altitude encoders take as much as 15 minutes to start working?
Did you know that when you install an altitude encoder with 10 foot increments, the controller only sees your altitude in 100 foot steps anyway?
Did you know that Mode A, Mode C, Mode S, and TCAS signals interfere with each other because they are on the same frequency at the same time?
Did you know that traffic spacing is often determined by the need to keep transponder signals from interfering? If the Lincoln Labs plan to use the transponder frequency for weather and traffic pictures is approved, our airspace capacity will be drastically reduced!
Did you know that the "reply" light blinks from interrogations, not replies?
Did you know that the official FAA Sun'n Fun arrival NOTAM specifies that we must turn off our transponders when approaching Lakeland? Isn't the purpose of the transponder to help protect against collisions? And aren't collisions more likely when there are lots of planes? Don't you think it's time to ask the officials why we should turn off our transponders when we need them the most?
Did you know that your transponder is rarely at fault when the controller says it has a problem? The fault is almost always overload of the antiquated, obsolete FAA equipment.
Did you know that the common ATC phrase "recycle your transponder" has no meaning?
Did you know that, inside your transponder, it knows when it is exchanging data with a nearby TCAS-equipped airliner or other heavy aircraft? If your transponder's only purpose is safety, and it is sitting there on your panel, and it knows you have traffic, shouldn't your transponder warn you about the traffic?
Did you know that the Airsport Transponder Monitor/Altitude Alerteris a great help in dealing with these problems? This column only scratched the surface, there are many aspects of the pilot-controller relationship that depend on the transponder signal.