Questions tagged [transponder]

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.

Filter by
Sorted by
Tagged with
0 votes
0 answers
68 views

How we are getting more radar replies in Mode-S? [closed]

Strategy for my Mode-s Radar in a beamwidth is having 8 intervals IAS S UF11+ICS S IAS S UF11+ICS S While checking the data in ASTERIX 48/130 field, I am getting 8 replies for most of the SI capable ...
Manjit Kamal's user avatar
1 vote
1 answer
166 views

Why and how can TCAS and SSR transponder work at the received frequency of each other?

The TCAS sends interrogation pulses at 1030 MHz and receives replies at 1090 MHz. And the transponder replies interrogations at 1030 MHz receiving at 1090 MHz. There could be interference between them,...
Galaxx's user avatar
  • 13
1 vote
1 answer
121 views

Can an aircraft transmit Mode C when Mode A is in STANDBY or OFF?

I am a software developer in the aviation industry, so I do apologize if my terminology is not correct. What I want to know is - are there any cases in which the aircraft's Mode A is switched to OFF ...
Indigo's user avatar
  • 13
1 vote
1 answer
87 views

Reasons for ADSB PAPR Report Altitude Errors

We have just test flown a new 1090 ADSB installation, using Apareo Stratus ESG Transponder, which has internal GPS. The PAPR for the test flight show both Baro Alt and Geo Alt errors in the Missing ...
The Doc's user avatar
  • 41
0 votes
2 answers
154 views

Are squawk codes linked with flight info such as route and flight data?

So squawk codes are given to an aircraft prior to departure. We know that if the pilot inputs the wrong code, the data will not show up. So are squawk codes linked via computer to the aircraft’s ...
Boeing787's user avatar
  • 6,384
1 vote
0 answers
80 views

Mode S Transmission from Boeing 737 Integrated Standby Flight Display (ISFD) data?

During a recent flight, while in communication with London control*, we received a query about our RVSM (Reduced Vertical Separation Minima) compliance. Both the Captain's and First Officer's ...
tedioustortoise's user avatar
3 votes
1 answer
406 views

Where on the aircraft are transponders mounted?

For civil acft like B737-800 or B777-200, where is the location of transponder? I'm asking about the "responder", not the cockpit device.
longhaircat's user avatar
0 votes
0 answers
76 views

How does ADS-B get pressure altitude? [duplicate]

I have learned that ADS-B out broadcasts both Pressure altitude and GPS Altitude. GPS altitude is, obviously, available from the GPS, but where and how does it determine pressure altitude? Does it ...
Charles Bretana's user avatar
1 vote
1 answer
263 views

Why are there not more emergency squawk codes? [duplicate]

7500 is used for hijacking, 7600 for radio failure, and 7700 for any other emergency. I understand that 7600 and 7500 need special handling (you can't talk to ATC if your radio has failed, and a ...
Someone's user avatar
  • 7,117
2 votes
0 answers
101 views

Should the transponder be set to 2000 then STB or STB then 2000?

For Airbus aircraft,after the engines are turned off,we set the transponder squawk code to 2000 and then the mode to STB. Is it mandatory to set transponder 2000 and then STB?Can we set STB and then ...
afanti's user avatar
  • 51
1 vote
1 answer
132 views

Why does secondary radar interrogate Mode S or A/C transponders using intermode?

The MSSR MODE S Radar uses different protocols to interrogate A/C or Mode S transponders: Mode S ALL CALL: ...
Uniform's user avatar
  • 153
0 votes
1 answer
1k views

How does AWACS pick up enemy info like speed and altitude without transponder interrogation?

So basically, IFF can pick up friendly vehicles. I'm assuming that enemy planes will have their transponder off to minimize speed and altitude data. How does the AWACS determine enemy info to pass on ...
Boeing787's user avatar
  • 6,384
2 votes
1 answer
359 views

Even if an intruder aircraft isn't equipped with TCAS, can I detect them with my TCAS?

I'm wondering about the TCAS operation concept. If aircraft "A" is equipped with TCAS I or TCAS II equipment, and aircraft "B" isn't equipped with either TCAS transponder or ...
PARK MIN's user avatar
16 votes
2 answers
4k views

Do airliners have a "switch" or other means of rapidly squawking emergency?

A standard means of informing Air Traffic Control of an emergency situation is to enter the code 7700 into the radar transponder. However, in a situation where the radios are busy and the crew is ...
Michael Hall's user avatar
  • 25.7k
4 votes
2 answers
524 views

Why do we need to enter squawk code when mode-s has ICAO 24-bit address?

Mode-S transponder was introduced to to eliminate reduced codes available to designate aircraft (4096 squawk codes) in a congested airspace. With the introduction of mode-S transponders, unique ICAO ...
Krishna Kanth's user avatar
6 votes
1 answer
263 views

How to reduce the volume of the GTN750 traffic warning beep?

We've got a GTN 750 with ADS-B IN and OUT. When we encounter traffic it emits a high pitched pulsing beep. It cannot be muted by any means - say you are on final and there's an aircraft holding short ...
ExternalUse's user avatar
3 votes
1 answer
2k views

Would the "Calibrated Altitude" figure on FlightRadar24 better be labelled "Pressure Altitude"?

On FlightRadar24, when a user clicks on an airplane icon, the data panel shown above is displayed. Note the figure labelled "calibrated altitude". For an airplane flying below the "...
quiet flyer's user avatar
  • 22.2k
0 votes
0 answers
67 views

Quality indicators ADS-B out & Ground Station receiver

I have a question about quality indicators parameters: I discussed with a pilot about quality indicators . We talked about NIC and NACp parameters I received his quality indicators in my ADS-B Ground ...
Oussama SDR's user avatar
5 votes
1 answer
710 views

Is a Mode S address changed when an aircraft is sold to another country?

The 24 bit Mode S address is issued by the national CAA where the aircraft is registered. If it is sold to another country, with another CAA, is the Mode S address maintained or is a new one assigned?
Samba Baldé's user avatar
9 votes
1 answer
2k views

Does ADS-B use its own antenna?

In the aircraft we have: ADS-B out/in using 1090ES A/C or Mode S transponder for SSR grounding interrogation. Does the ADS-B out use the same antenna as Mode S or does it use its own antenna?
Oussama SDR's user avatar
5 votes
1 answer
2k views

Why is 5 seconds the time to respond to a TCAS RA?

With TCAS, the time to respond to an RA is 5 seconds (2.5 seconds for a reversal RA). The FCOM states that the TAU (estimated time) before the aircraft intruder reaches the "Closest Point of ...
user38116's user avatar
  • 453
6 votes
2 answers
3k views

Why should you never squawk 0000 in the USA?

FAA Order 7110.66E says Code "0000" should never be assigned or used. and Code 0000 must never be assigned However, NASA recommends that crews set 0000 after landing to help detect when ...
Steve V.'s user avatar
  • 23.2k
4 votes
1 answer
668 views

Does the ATC not receiving Mode C and intermittently other transponder information imply that the Mode S transponder itself has an issue?

I had ATC report to me inflight today that they were not receiving my Mode C (altitude data). Intermittently, they also reported they were not seeing any other transponder information. My transponder ...
Charles Bretana's user avatar
2 votes
1 answer
209 views

Can a formation flight operate in class B if only the lead aircraft is equipped with a transponder?

We all know that you can't fly in Class B airspace without a transponder. But, when doing a formation flight, only the lead plane has their transponder turned on. Does that mean that it's possible for ...
HiddenWindshield's user avatar
5 votes
2 answers
1k views

Why is a Mode S transponder required to be installed and working for TCAS II to be operational?

I am wondering why a Mode S transponder is required to be installed and working for TCAS II to be operational? I read such phrase in Eurocontrol ACAS II guide and I don't understand why mode A/C is ...
Konrad's user avatar
  • 1,963
2 votes
1 answer
2k views

Does TCAS II work and give RA with Mode C or Mode A transponders?

What's the minimum requirement for TCAS II RAs to be generated? Will we get RA if we have mode C transponder and the other aircraft also has mode C? Will mode A work as well?
Sachin Chaudhary's user avatar
7 votes
1 answer
2k views

Why does TCAS need 2 antennas?

Can someone explain why TCAS needs 2 antennas (one on the top of the fuselage and one on the bottom)? And why is the top one directional and the bottom one can be either omnidirectional or directional?...
Konrad's user avatar
  • 1,963
0 votes
1 answer
2k views

Can single engine/smaller aircraft turn off ADS-B?

I was just looking at the adsbexchange website, and was wondering if it was possible for smaller, private aircraft to turn off their ADS-B? I was wondering this because id figure that maybe not ...
Obama. The real obama.'s user avatar
2 votes
1 answer
527 views

Is transponder required to turn off in formation flying?

When planes are flying in formation, TCAS will undoubtedly alert the crew. As a result, in this instance, the transponder must be turned off. The pilot must, however, rely on eyesight rather than ...
Auberron's user avatar
  • 1,567
11 votes
2 answers
779 views

Why are gliders oftentimes not equipped with a transponder?

Oftentimes gliders are not equipped with transponders (at least in Europe). Even if they are, they do not necessarily operate it at all times. This is allowed by SERA.13001: (a) When an aircraft ...
yankee's user avatar
  • 1,073
3 votes
1 answer
2k views

What does prevent installing an ADS-B transponder on a vehicle?

FlightRadar24 indicates they also track ground vehicles: Ground vehicles visible on Flightradar24 are generally those that are most active in the movement areas of an airport, like airport rescue and ...
Furkan Karaman's user avatar
5 votes
2 answers
3k views

How far can a plane squawking 7700 be heard and how quickly will the news spread?

This is just an idle question I have after watching Non-Stop (2014), but suppose a plane (let's assume a Boeing 767-400) is over the Atlantic and sets its transponder to indicate it's in an emergency. ...
Joshua Snider's user avatar
1 vote
0 answers
211 views

Why does the A320 transponder's CLR button do two different things, depending on how many digits were entered?

I have to admit I've only flown in simulators but everyone of them implements the "CLR" button of the transponder in an A320 (maybe also others) the following way: It removes the fourth ...
xZise's user avatar
  • 111
7 votes
1 answer
355 views

Why bits are mixed up (interleaved) during ATC transponder mode A and mode C reply format?

In the image above from radartutorial.eu, we can see that the sequence of bits are c1 a1 c2 a2 c4 a4 during the reply of ATC transponder mode A. Why are the bits not transmitted like c1 c2 c4 then a1 ...
Tough questions's user avatar
-3 votes
1 answer
310 views

What information does Mode S provide?

What information about own aircraft does TCAS Mode s( all call) send in the interrogation? What information does Mode S transponder(intruder)replay to TCAS interrogation?
user52906's user avatar
1 vote
0 answers
116 views

Is a Mode S transponder required as part of TCAS I?

Is a Mode S transponder required as part of TCAS I?
user52906's user avatar
2 votes
1 answer
2k views

What is the difference between SSR and ADS-B?

Can someone explain what is the difference between SSR transponder and ADS-B. From what I know ADS-B is a capability that can be incorporated into a transponder, but I do not understand the difference ...
Konrad's user avatar
  • 1,963
0 votes
1 answer
259 views

How can I know if the Garmin GTX 345 transponder supports modes A and C?

How can I know if the GTX 345 supports mode A/C? I did not find a mention in the installation manual the capability of mode A/C.
user52906's user avatar
1 vote
3 answers
408 views

Are mode C altitude returns valid for aircraft separation?

According to FAA JO 7110.65 5-12-8 'Validation of MODE C READOUT', Mode C is valid if there is less than 300 feet deviation from the pilot reported altitude. If ATC instruct 'A' aircraft to maintain 5,...
Min's user avatar
  • 661
1 vote
1 answer
282 views

Why does CFR §91.215 part (b) list specific areas for transponder operations?

Why does part (b) list individual sections where transponder operations are required when part (c) states that transponder operation is required in all controlled airspace? All sections listed in part ...
Carry On Flying's user avatar
7 votes
1 answer
478 views

How are both squawk and altitude transmited when operating a Transponder in Mode C?

I know that in Mode $3$ (which includes Mode A and Mode C) the aircraft transmits $12$ information pulses. That corresponds to $2^{12}=4096$ squawk combinations in Mode A which are sent to ATC to ...
Darjan's user avatar
  • 1,145
4 votes
4 answers
8k views

Is it legal to fly without a transponder?

Everything is legal / airworthy. Except: Transponder is installed. It does work. It has NOT been inspected in any time frame that would show it is properly maintained. Flight is Golf, Echo, Delta &...
chup's user avatar
  • 191
34 votes
2 answers
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 ...
HiddenWindshield's user avatar
0 votes
2 answers
298 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 ...
Mamazi-Avia's user avatar
0 votes
1 answer
260 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?

For airspace within the 48 contiguous states and the District of Columbia: For aircraft originally certificated without engine-driven electrical systems (and not subsequently certified with such a ...
quiet flyer's user avatar
  • 22.2k
2 votes
1 answer
205 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 ...
Jules's user avatar
  • 975
6 votes
3 answers
616 views

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

In the US, would FAR 91.227, or any other regulation or law, forbid use of ADS-B-out in an unregistered ultralight? Could the N-number field simply be left blank, without violating any regulation or ...
quiet flyer's user avatar
  • 22.2k
1 vote
1 answer
2k 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 ...
Paul's user avatar
  • 11
2 votes
2 answers
3k 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 ...
nodapic's user avatar
  • 1,817
3 votes
1 answer
165 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 ...
TelegraphOperator's user avatar