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 for a plane with no electrical system, and obviously at a towered field where I would be communicating with ATC using a portable radio. No flight plans will be involved and I will generally be flying out of a class B field but within a class B umbrella. Flights will be VFR/daytime only.

EDIT: Looks like I opened up quite a can o' worms, here. I didn't know it would be this complicated. Just found this, too, which adds some more info. Thanks for the lively debate and the good suggestions.


Looks like it's getting more and more difficult to escape government control. I think I may have to get a transponder. Hmmm.

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    $\begingroup$ If you are within a "Class-B umbrella" you are inside a Mode-C veil, and you must be equipped with a transponder. $\endgroup$
    – Ron Beyer
    May 4, 2018 at 17:02
  • $\begingroup$ Related $\endgroup$
    – Pondlife
    May 4, 2018 at 18:11

4 Answers 4


From the AOPA:

Flying into a Mode C Veil Without a Transponder

For flying into a Mode C veil without an operable transponder, the pilot needs to telephone the appropriate radar facility for the Class B airspace and ask for permission to make the flight. Upon agreeing to conditions (including direction of flight and altitude), the pilot will be given a code number that he will mention to the controller upon initial radio contact. This is the same procedure that a pilot with an inoperative transponder/encoder would use to fly in or out of the Mode C-veil airports for avionics repair.

The situation may be slightly different if the pilot is landing at a satellite Class D (towered controlled) airport within the veil but outside of Class B airspace. The approval is still given by the controlling radar facility via telephone. The radar facility may still issue the code number but may only require the pilot to contact the tower in the Class D airspace.

NOTE: You should not expect approvals at the busiest of Class B airports during their peak times or under difficult weather conditions, but if this telephone procedure can expand the utilization of your aircraft occasionally, then by all means, phone to find if you can "fit into" the system.


None of the answers have actually addressed the question in the title, instead (justifiably) focusing on the problem of you planning to fly within the Mode-C veil around a Class B airport without a transponder.

So to answer the question, ignoring the issue of whether you personally need a transponder for your situation... use the phraseology NEGATIVE TRANSPONDER, like so:

Podunk Approach, Skychicken 321AB, VFR request, negative transponder. Three-zero miles east of Podunk VOR, heading three three zero.

Controllers can provide radar services to primary-only targets for as long as surveillance capability allows. Obviously the controllers cannot use secondary-radar (beacon) methods of positively identifying your target, so they have to use one of the three primary-radar methods prescribed in the 7110.65 5–3–2:

  1. The target appears on the scope within 1 mile of the departure end of the runway, and the tower controller told the radar controller that the aircraft was rolling.
  2. The pilot reports both their current position relative to a fix (VOR, intersection, airport, etc) displayed on the controller's scope, AND their heading or route of flight; and a single target is observed which corresponds to that report.
  3. The pilot reports their position such that the controller is satisfied that the aircraft is within radar coverage and should be visible on the scope; the controller issues an identifying turn of 30º or more; and a single target is observed making the turns.

Handily, the methods are presented in order of how quick and easy they are for the controller to implement.


First I assume this is for VFR flights and I assume this is for flight following. In the US if you are flying in Class G airspace or Class E below 10,000 feet you are not required to have a transponder. In this case you would tell ATC that you do not have a transponder but if that were the case I would doubt the controller would want to do flight following as they won't have your altitude information. You are not required to contact ATC if flying VFR in Class G and Class E airspace.

One exception to the transponder rule is that if you are flying an aircraft that was certified without an electrical system. These are usually very old vintage aircraft and they literally have no electrical system and no radio either. If that is the case you will have to pre-coordinate with ATC and the control towers of the departure and arrival airport to let them know you have no transponder or radio. The tower can use light gun signals to let you know you have clearance to land.

If you do pick up a transponder for your plane be sure to install an ADS-B out transponder as these transponders will be required beginning January 1, 2020.

  • 1
    $\begingroup$ No except to just clarify that you are flying VFR. VFR aircraft usually squawk 1200 anyway. I know at Class D airports they don't give you a squawk code if flying VFR but they probably would give you a squawk code in Class B and C airports. What class airspace is your airport in? $\endgroup$
    – DLH
    May 4, 2018 at 16:41
  • 3
    $\begingroup$ @birdus: Mode C transponder is often required within 30NM of the primary airport of Class B airspace, regardless of the altitude or the underlying airspace type. So even if the airport you're concerned with is in Class D airspace, you may need a transponder. $\endgroup$ May 4, 2018 at 16:57
  • 1
    $\begingroup$ @birdus: The best answer for you is just to pre-coordinate with ATC before takeoff and let them know you don't have a transponder. Fred Larson is right that if you are withing the Class B airspace 30 NM veil you will need a transponder regardless. Only way to fly in that case is through pre-coordination with ATC to get a "waiver". ATC is pretty flexible on these things if you pre-coordinate. $\endgroup$
    – DLH
    May 4, 2018 at 16:59
  • 1
    $\begingroup$ What Fred said: You'll be within the SeaTac Mode C veil, and underneath the Bravo shelf. A Transponder is required. You cannot legally base the plane you describe at TIW. $\endgroup$
    – abelenky
    May 4, 2018 at 17:00
  • 3
    $\begingroup$ @birdus: The best thing for you to do is contact your FAA Standards Office and give them your situation and work it out with them. You may want to look for an airport outside the 30 NM veil to make your life easier. $\endgroup$
    – DLH
    May 4, 2018 at 17:06

@birdus 14 CFR 91.225:

(d) After January 1, 2020, and unless otherwise authorized by ATC, no person may operate an aircraft in the following airspace unless the aircraft has equipment installed that meets the requirements in paragraph (b) of this section:

(1) Class B and Class C airspace areas;

(2) Except as provided for in paragraph (e) of this section, within 30 nautical miles of an airport listed in appendix D, section 1 to this part from the surface upward to 10,000 feet MSL;

(3) Above the ceiling and within the lateral boundaries of a Class B or Class C airspace area designated for an airport upward to 10,000 feet MSL;

(4) Except as provided in paragraph (e) of this section, Class E airspace within 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

(5) Class E airspace at and above 3,000 feet MSL over the Gulf of Mexico from the coastline of the United States out to 12 nautical miles.

(e) The requirements of paragraph (b) of this section do not apply to any aircraft that was not originally certificated with an electrical system, or that has not subsequently been certified with such a system installed, including balloons and gliders. These aircraft may conduct operations without ADS-B Out in the airspace specified in paragraphs (d)(2) and (d)(4) of this section. Operations authorized by this section must be conducted—

(1) Outside any Class B or Class C airspace area; and

(2) Below the altitude of the ceiling of a Class B or Class C airspace area designated for an airport, or 10,000 feet MSL, whichever is lower.

  • 2
    $\begingroup$ Please use quote formatting to make it clear what is a quote and what are your own words. Also, I don't see how this answers the question about phraseology with ATC. $\endgroup$
    – Pondlife
    May 4, 2018 at 18:00
  • $\begingroup$ The answer was already provided to the initial question by Ron Beyer: "Unable, not equipped" $\endgroup$
    – CrossRoads
    May 4, 2018 at 18:35
  • 5
    $\begingroup$ @CrossRoads Ron added a comment, not an answer. There's a big difference: see this meta question for more details. Because this is a Q&A site, not a discussion forum, we expect answers to answer the specific question asked. You might like to review the tour and help center for more information about the StackExchange model (none of this is specific to aviation.SE). $\endgroup$
    – Pondlife
    May 4, 2018 at 19:06
  • 1
    $\begingroup$ Could you at least explain what "paragraph (b) of this section" is about? The part you quoted only explains where it applies but not what the actual requirement is. And it still doesn't answer the question about talking to ATC. $\endgroup$
    – fooot
    May 8, 2018 at 14:56
  • $\begingroup$ @CrossRoads can you please edit your answer to address at least fooot's comment? $\endgroup$
    – Federico
    May 18, 2018 at 12:55

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