Why would a pilot ever need to turn off a plane's transponder?

Question

For that matter, why would there even be a switch to turn it off in the first place? Why is it made so simple for a pilot to avoid being tracked?

Answer 1

1. In case of electrical failure, shedding unnecessary electronics might give you a few more minutes of 2-way communication. ATC can see you without the transponder; they just don't get altitude info.

2. When flying VFR outside Class C or B airspace it's not required. Some of us prefer not to have other people watching us every second.

3. Sometimes it will go nuts and you'll be asked to turn it off.

4. You might need to turn it off in order to turn on your backup transponder in the event the first one fails.

A better question is why do you think pilots should be "tracked"? Would you approve of a device in your car that allowed the federal government to know where you drive 24/7 and for them to keep a record of your travels? Sure, you may have nothing to hide, but isn't that just an invasion of privacy? A transponder is fine when flying "in the system" on an IFR flightplan because it helps ATC maintain separation. That's what they are required to do and it's what I want them to do. But when I'm just out flying on a nice day and I'm not in airspace that requires a transponder, it's my right to shut it off.

Answer 2

In some airspace you aren't even required to have a transponder. Most bush pilots in Alaska fly without transponders (unless they transit Anchorage or Fairbanks). To them, that is weight that can better be used for cargo. Shoot some of them don't even have radios for the same reason.

You only have to have a transponder if you are flying in Class A, B, or C airspace. Personally, I agree with you that in most cases there is no good reason not to have your transponder on. It's a safety thing unless - see below.

In the military, there are some missions that you really don't want people to know exactly where you are. Also, as mentioned, flying formation, lead is the only aircraft that transmits mode C because ATC will get a warning that two aircraft are flying too close. Or if there are a lot of aircraft in the same vicinity, i.e. Osh Kosh, fighting wildfires, etc.

Answer 3

It's so you can easily turn it off in the event it is malfunctioning. ATC will sometimes ask you to do that. It's also there for formation flying or flying into certain areas where ATC doesn't want you to have your transponder on (OshKosh maybe?). Unfortunately, some pilots use that to avoid being tracked, however, taking away the off switch wouldn't stop it. There always needs to be circuit breakers for it in case it starts smoking or catches on fire, or something like that.

Answer 4

There should be a failsafe electronic method for tracking every scheduled passenger jet that is pilot proof and independent of the main electrical systems. The satellite service offered by Boeing for registering plane behavior should perhaps be made compulsory. We are not talking about a small crop-spraying type plane with one pilot. The lives of passengers should not be subject to the vagaries of malicious intent. At the very minimum with electronic tracking we would know if the plane was underwater or on land.

Answer 5

The only reason to turn it off completely is if a malfunction occurs that might cause problems for ATC or other aircraft.

Aircraft can be tracked on radar with or without a transponder.

It is vastly easier to track an aircraft than it is to track any other vehicle, so if you are worried about mythical bad guys hiding from Big Brother, aviation is the last domain to be concerned about.

Answer 6

I've been told by Tower to turn it to standby while doing touch and gos because the GA runway is next to the main runway with the heavies landing. If all the little cessnas were squawking the 747, DC10 etc. pilots will have their transponder detect equipment screaming at them during takeoff and landing.

Answer 7

Generally it's polite to leave your transponder off while on the ground, and to turn in on just prior to taking the runway.

If you have traffic alert equipment on your airplane it goes mental around all those transponders.

There are other good answers here too. I just didn't see this particular reason listed.

Answer 8

sometimes, depending on where you are flying, ATC will ask you to turn your transponder off to clear the clutter on their screen. If you are well below the mass of the traffic, they will not need to keep a constant eye on you. This happens very seldom though.

Answer 9

Well being an old Air Force Electronics tech I'd say that in the event it began emitting smoke, which electronics equipment is known to do from time to time, I'd definitely want a way to turn it off. Besides you don't want to remove or install it without turning it off. Arcing while installing or removing cables ain't nice.

Answer 10

some folks need to read 91.215
(i) In all airspace of the 48 contiguous states and the District of Columbia at and above 10,000 feet MSL, excluding the airspace at and below 2,500 feet above the surface; and

(ii) In the airspace from the surface to 10,000 feet MSL within a 10-nautical-mile radius of any airport listed in appendix D, section 2 of this part, excluding the airspace below 1,200 feet outside of the lateral boundaries of the surface area of the airspace designated for that airport.