Aviation

Questions tagged [transponder]

Ask Question

A radar transponder is a radio beacon on an aircraft that replies to a radar interrogation. The transponder encodes information into the reply, allowing air traffic control to know the aircraft's altitude and identity.

70 questions
Newest
Active
Bountied
Unanswered
Filter by
Sorted by
Tagged with
32
votes
2answers
5k views

Should I contact ATC if I don't have a transponder?

The flight school I usually rent from is under the shelf of class C airspace. If you're going out to a practice area, the standard procedure is to contact approach control and get a squawk code, so ...
0
votes
2answers
144 views

Is it possible for squawk to change automatically in emergency situations?

It might be a silly question, but is it possible for an airliner to automatically switch the squawk code to emergency (7700) during a flight? (For example in case of losing all engines) Thank You In ...
0
votes
1answer
69 views

Does the FAA construe FAR 91.225 to prohibit aircraft w/o electrical systems w/o ADS-B-out from flying above 10,000' MSL unless below 2500' AGL?

Does the FAA construe FAR 91.225 as imposing a general prohibition on flight above 10,000' MSL (excluding airspace below 2500' AGL) in aircraft without ADS-B-out, even for aircraft without engine-...
2
votes
1answer
67 views

Are there any situations where it's beneficial to disable altitude reporting in TCAS?

Having altitude reporting enabled persistently seems like a pretty common-sense thing to do -- it enables RA in addition to TA, the benefits of which are fairly obvious. That said, most of the common ...
3
votes
0answers
49 views

Would FAR 91.227, or any other regulation, forbid use of ADS-B-out in an unregistered ultralight?

Would FAR 91.227, or any other regulation, forbid use of ADS-B-out in an unregistered ultralight? Could the N-number field simply be left blank, without violating any regulation or law? One possibly ...
1
vote
1answer
220 views

Why do I never see fighter jets on sites like FlighRadar24 and ADBSExchange.com [duplicate]

On ADS-B Exchange they even have a filter option for military aircraft, and it will show all kinds of transport, mid-air refuelers, helicopters, and even training aircraft like the Texan, but I don't ...
2
votes
2answers
836 views

Is a Mode C or S Transponder a type of Mode 3 Transponder?

Mode A transponders are sometimes referred to as Mode 3/A transponders. According to NATO STANAG 4193 (not publicly available, summary from Wikipedia), the "3" in that description refers to the mode ...
3
votes
1answer
77 views

Why is Mode C helpful for ASDE-X systems?

Airports that operate an ASDE-X system require aircraft to operate transponders in mode C while moving on the surface. While I understand the general purpose of operating the transponder to ...
0
votes
1answer
179 views

Are Transponder Mode A and C still in use?

Are the ATC transponder Mode A and Mode C still in use (according to ICAO or FAA rules)?
0
votes
1answer
231 views

FAR 91.215 (b)(3)(ii) — transponders— does the “or below 10,000' MSL” clause have any practical significance?

Here are some of the airspaces where FAR 91.215 requires aircraft to have transponders-- (b) ... (2) All aircraft. In all airspace within 30 nautical miles of an airport listed in appendix D,...
0
votes
1answer
211 views

FAR 91.215— may an aircraft with no electrical system and no transponder overfly Wheeler AAF at 9500' MSL?

Here are some of the airspaces where FAR 91.215 requires aircraft to have transponders-- (b) ... (2) All aircraft. In all airspace within 30 nautical miles of an airport listed in appendix D,...
0
votes
1answer
140 views

What additional airspace will be off-limits to an a/c w/ no elect. system or xponder under 91.225 (ADS-B) compared to under 91.215?

Under FAR 91.225 (requirement for ADS-B-out), what additional airspace over the 48 contiguous states in the U.S. will be off-limits to an aircraft w/ no electrical system or transponder, compared to ...
1
vote
2answers
182 views

How feasible digital radio communications would be? [closed]

Its been over 100 years since we first flew and we still use analog radio with parasites and "radio effect" which changes your sound. Why don't we ditch the old system and make a mandate a new law ...
15
votes
7answers
4k views

Why do (or did, until very recently) aircraft transponders wait to be interrogated before broadcasting beacon signals?

An aircraft’s transponder transmits signals that announce (at the very least) the aircraft’s identity, altitude, and direction of motion (plus, for most newer aircraft, a whole slew of other useful ...
2
votes
1answer
186 views

Why does setting the Legacy 600's transponder to standby mode also deactivate its TCAS?

In 2006, a 737 operating as Gol Transportes Aéreos Flight 1907 crashed following a collision with a Legacy 600 business jet; the Legacy's transponder proved to have been in standby mode1 at the time ...
0
votes
3answers
147 views

What does the future of the weather radars look like?

Planes had weather radars for a long time (Dassault Falcon and Learjet35A) which was useful since you either had to ask ATC, listen the ATIS frequency or ask the flight advisory before flight planning ...
8
votes
2answers
9k views

What is the purpose of squawking 7777?

Aircraft use transponders to communicate to ATC their position and status. Some squawk codes are reserved, such as 7700 (emergency), 7600 (communication failure), 7500 (hijacking), 1202 (glider), 1200 ...
9
votes
2answers
989 views

What do you squawk when multiple conditions apply?

There are three standard transponder codes for exceptional situations: 7500 (hijacking), 7600 (radio failure), and 7700 (general emergency). Which code do you use if multiple situations apply? For ...
5
votes
3answers
1k views

Is a mode C transponder required underneath Class C airspace?

FAR 91.215 states that a mode C transponder is required for... all aircraft in all airspace above the ceiling and within the lateral boundaries of a Class B or Class C airspace area designated ...
22
votes
2answers
3k views

Should I switch the transponder to STBY or not while changing codes?

I´m now reading Bob Gardner’s book “Say again, please” and there is this instruction on page 54: Do not turn the transponder function switch to STBY while changing codes. What is the reason for ...
10
votes
3answers
804 views

In a part 91 formation flight within a mode C veil, are all the aircraft required to have their transponders on?

Two aircraft are planning on conducting a standard formation flight (aircraft remaining within 1 mile of each other) as follows in the U.S.: Maintaining VFR below 10,000 MSL; Remaining outside/clear ...
1
vote
0answers
252 views

How to keep a Garmin GTX330 turned off when powering on avionics?

There seems to be an option in the GTX 330 settings that keeps to unit from powering on when receiveing power from the power system. I flew in two different airplanes and one immediately powered on ...
0
votes
1answer
473 views

If a pilot has the wrong altimeter setting, will his transponder mode C altitude be off too? [duplicate]

Just wondering if the transponder mode C reported altitude will be off if the pilot accidentally has the wrong altimeter setting.
5
votes
1answer
916 views

Why would a Mode-C transponder report a different altitude than an altimeter/GPS?

This is related to a small single-engined plane. On a recent flight, the controller kept telling me that I was 300 ft higher than it appeared on my altimeter and GPS (which were in sync). This was ...
3
votes
1answer
415 views

When do controllers assign a squawk code to VFR aircraft in Canada?

In all of my previous flying experience the controllers provided a squawk code only when I requested flight following. On a recent flight from Buttonville, Ontario (CYKZ), the controller provided a ...
1
vote
2answers
249 views

Is a VFR flight following request implied when talking to tower and advising them of your intended airport?

If I am at a towered airport in class delta airspace and I'm departing VFR and tell the ground where I want to go, is it implied to the controller that I'm requesting VFR flight following? Let's say ...
1
vote
2answers
659 views

What requirements do A&Ps (AMT) have to work on avionics?

Is there any additional requirement for A&Ps to work on avionics or is that even a totally different license? I just wonder why only a few A&Ps I met, also do avionics.
12
votes
3answers
7k views

How do I tell ATC that I don't have a transponder?

If my plane doesn't have a transponder and ATC tells me to squawk some transponder code, how should I respond? Is it just as simple as "I don't have a transponder"? This is for the United States and ...
10
votes
3answers
2k views

How does ATC locate a stealth aircraft if its transponder fails?

Stealth aircraft are built to have near-zero radar visibility, so that, in a warzone, it'll be harder for the enemy to see it on their radars to shoot it down. However, air traffic control also use ...
3
votes
2answers
577 views

If the static port get blocked, and no alternate static air source is fitted, will the transponder keep provide mode C?

If the static port get blocked for any reasons and the aircraft is not fitted with an alternate static source while in Mode C with SSR, will the ATC still get the height information from my ...
5
votes
1answer
3k views

Which antenna on an commercial airline airplane is used for the transponder (SSR)?

On the 767-200 image I see no SSR antenna, but since that TCAS uses the transponder I guess that are sharing the same antenna. Am I right ?]1
9
votes
1answer
2k views

What is Mode B on the transponder?

Mode A selected on the transponder provides identification of the aircraft to the secondary radar; Mode C will add an automatic height read-out of an aircraft. Mode S is a selective addressing. But ...
0
votes
1answer
425 views

What Height Atc radar reads from pilot selection [duplicate]

Just want to know whether ATC radar always reads aircraft height with respect to standard altitude setting or will read the change in height if we select QNH instead of standard 1013 hPa (QNE)?
17
votes
2answers
2k views

Which source to use when reporting the current altitude to ATC?

While flying from KSNA to KVCB VFR at night, Norcal Approach asked for my current altitude. I was somewhere between 12.0 and 12.5 depending on which reading I was going to use. ATC had me confirm. ...
3
votes
1answer
443 views

Can a TCAS be alerted when the intruder aircraft has a transponder in stand-by mode?

Can a TCAS give a TAs (traffic advisories) if the intruder aircraft has a transponder in stand-by mode?
6
votes
3answers
2k views

How does the modulation of the transponder work?

The transponder works in PCM (pulse code modulation): how does it work in the transponder? I can find explanation of what PCM is, but not if the signal sent from the transponder antenna is digital or ...
-2
votes
1answer
278 views

Why don't transponders send gps coordinates and other important info in addition to altitude and transponder code?

I heard that they were waiting for the patent holder's patent to expire, but just wanted to confirm.
1
vote
1answer
370 views

Are experimental aircraft exempted from the 2 year transponder and avionics checks?

Experimental aircraft and LAS. The 2 year verification test for avionics , transponder and altitude encoder. Are experimental aircraft exempted from this test or they must comply ?
6
votes
1answer
1k views

What's required for the ADS-B to function? A GPS or Mode S Transponder?

Jeppesen defines the ADS-B as a surveillance system broadcasting GPS-derived positions and other information such as velocity over the data link. Yet, the Wiki article on ADS-B relates it to the Mode ...
44
votes
6answers
14k views

Why is the range of transponder digits 0 to 7 rather than 0 to 9?

As a controller on IVAO I sometimes assign codes like 0168 and find out later that the code isn’t valid. For me, the range 0-9 seems more logical. Why do we have to use octal numbers and not decimal?
7
votes
1answer
1k views

Is it recommended to have an ADS-B transponder in ALT mode on the ground? [duplicate]

Early on in training I was told that unless the airport specifically noted it on the chart, that the transponder was turned to ALT (altitude) mode just prior to taking the runway for take-off (lights, ...
13
votes
2answers
2k views

Are transponders required for hot-air balloons in the US when operating within a Mode C Veil?

I've taken some people flying recently for fun, and they noticed some hot-air balloons and asked me if they had transponders. In San Diego (Southern California) I often see hot air balloons well ...
3
votes
1answer
1k views

After purchasing an aircraft, how do I put the transponder in my name?

I just purchased an aircraft and the prior owner said that I need to put the transponder to my name. What is the procedure to do that?
35
votes
9answers
12k views

Can a military pilot make his airplane invisible for the ATCs?

I'm writing a story about the pilot of the Austrian Air Force, who uses his Eurofighter Typhoon aircraft for unintended purposes. I've read stories in the internets that civil pilots allegedly can ...
5
votes
1answer
586 views

How does FlightAware correlate flights to Part 91 flight plan data?

I'm looking at some flights in FlightAware. With the scheduled air carrier flights, their call-sign can be crossreferenced with a flight schedule database to determine the origin and destination. How ...
7
votes
3answers
7k views

What is the ICAO 24-bit code used for?

I know that each transponder is linked to a unique 24-bit code assigned by ICAO. But to be seen by the Secondary surveillance radar the pilot set the squawk code (4 digit octal code) on the ...
5
votes
1answer
1k views

Is there a relation between the Mode 3/A Code and the ICAO aircraft address?

I would like to know is there is any way to match mode 3/a code (which is assigned by ATC to aircraft) and ICAO address of the aircraft. I mean how mode 3/a code is assigned to each aircraft by ATC? ...
4
votes
3answers
703 views

What aircraft would have these tail numbers?

Last night I was looking at a flight radar on my phone, and I saw two blips flying close to each other over Camden, NJ. They were heading northeast at around 250 knots, and the only information ...
18
votes
3answers
3k views

Why do the transponders introduce codes instead of using aircraft registration numbers?

(A non-pilot here, just a Aviation.SE reader, recently into listening to ATC. I am wondering...) Why do the transponders use their own codes? (squawk) It seems to me, it would be safer and less of a ...
7
votes
1answer
430 views

Do interceptor squawk codes suppress TCAS RAs?

Some parts of the world reserve a discrete squawk code for use by military interceptor operations (in the NBCAP, code 7777 is used for this). Does this squawk code, or some equivalent value, suppress ...

1
2