Airplane Bluetooth transmitters: match the seat jack and both headphones

By Daily Carry Lab. Primary documentation checked October 14, 2026 (Pacific).

Affiliate disclosure: As an Amazon Associate, Daily Carry Lab earns from qualifying purchases. Retailer links may earn a commission at no extra cost to you.

Research disclosure: We have not tested these products. Selection uses primary documentation and the compatibility decisions below; no DCL ratings or measured performance are claimed.

Choose an airplane Bluetooth transmitter by the seat’s audio output and your headphones, then by battery and controls. It sends audio from a wired headphone jack to Bluetooth headphones. It does not create entertainment on a seat without an audio source, and a USB charging socket is not the same thing as an audio output.

We selected Twelve South AirFly Pro 2 and Avantree Relay BTTC-218 because both document two-headphone listening from a 3.5mm source. The Pro 2 also documents a receive mode for a separate AUX-input use. We have not measured latency, sound quality, connection reliability or battery endurance.

Original DCL research schematic, October 29, 2026; documented choices, not a product photograph or DCL test.

AirFly View adds a visible pairing interface, with different battery planning

If identifying the connected headphones is your main difficulty, add AirFly View, Black to the comparison. Twelve South’s exact View page, checked October 29, 2026, documents a display that guides setup and shows connected headphone names. It supports two listeners and both transmit and receive modes. That is a different interface choice from the Pro 2’s separate pairing controls; it does not establish better sound or fewer dropouts.

Decision	View documentation	Practical tradeoff
Check which headphones are connected	On-screen headphone names; Menu > Add Device for a second pair	You still need headphones in pairing mode
Share ordinary wired-source audio	Two headphone connections in TX mode	Verify both actual pairs before travel
Feed a separate AUX-input system	RX selected through the menu	Input/output direction still matters
Investigate broadcast listening	Auracast mode requires compatible listening devices	Ordinary Bluetooth support alone does not establish Auracast support

Twelve South lists up to 16 hours of battery life and USB-C recharging for View. Keep that separate from the Pro 2’s 25+ hour statement above: neither is DCL endurance testing, and the page does not establish equal test conditions. A screen can be a useful selection reason without making View the longer-runtime choice. Plan a charging opportunity if the documented ceiling leaves too little margin for your itinerary.

The View page lists a travel case and international airline adapter. That is manufacturer package evidence for this model, not approval of a third-party bundle or a universal seat-jack fit. Compare the complete offer and actual flight’s audio socket before ordering; do not transfer Pro 2 Deluxe contents or Pro 2 reset controls to View.

Budget and selection: current delivered totals are unknown here. Retain a suitable transmitter if its pairing controls already work for you. Investigate View when seeing the connections addresses a specific problem, then check the complete kit and both headphone pairs. No View retailer mapping has been verified, so this addition uses primary links only. We have not tested the display, pairing, synchronization or Auracast, and do not repeat the maker’s promotional promise of perfectly synchronized audio.

Compare the exact models

Model	Source and listening setup	Manufacturer battery statement	Main buying check
AirFly Pro 2, standard white	Standard headphone jack to two wireless headphones; TX/RX mode switch	25+ hours; USB-C recharging	Standard package versus Deluxe/international adapter package
Avantree Relay BTTC-218, black single unit	3.5mm audio output to two Bluetooth headphones	Up to 20 hours	Exact seat jack, any required adapter and both headphone models

Sources: AirFly Pro 2 specifications, Avantree’s airplane-use explanation, and Relay’s current manual. Battery figures use the manufacturers’ different wording; they are not comparable DCL test results or a promise for a particular flight.

AirFly Pro 2: separate pairing controls and a receive mode

The Pro 2 has separate Pair 1 and Pair 2 controls, volume/mute controls and a battery indicator. Its documented receive mode allows a Bluetooth source to feed an AUX-input device, such as a suitable stereo. For the seatback-to-headphones use, select transmit mode and use an audio output jack.

The standard model and Deluxe package should not be treated as identical contents. Twelve South specifies its International Airline Adapter and a faux-suede bag with Deluxe; verify whether the standard package and any extra adapter meet your seat’s jack arrangement before ordering. A double-prong airline socket may require an appropriate adapter; a standard 3.5mm plug is not a universal fit claim.

Drawback: the long codec list does not establish that your headphones can use every codec. The product’s headline battery figure also does not establish how long two particular headphone pairs will stay connected.

Relay: follow the two-headphone sequence

Avantree’s BTTC-218 manual says to connect the first headphones, keep them connected, then hold the multifunction pairing button for two seconds and pair the second set. Both headphone indicators should become solid blue. Turning headphones on alone may not put them in pairing mode, and a nearby phone can reconnect to them first.

The same manual separates three volume settings: source, Relay and headphones. A connected indicator with silence is a reason to check all three and confirm the plug is fully seated in an AUDIO OUT/headphone jack. It is not proof that the adapter or headphones are defective.

Drawback: Avantree recommends two over-ear pairs or two identical earbud sets for its most stable dual connection. That is a manufacturer setup recommendation, not a guarantee or a result we reproduced. Check the exact headphone combination before depending on it for shared listening.

Codec and compatibility limits

Twelve South’s mode-specific codec guidance lists aptX Adaptive, aptX Low Latency, aptX HD, aptX and SBC in Pro 2 transmit mode. It lists aptX HD, aptX, AAC and SBC in receive mode. AAC appearing in the receive list does not make it a transmit-mode codec.

A low-latency codec needs support at both ends. Do not turn a transmitter’s aptX label into a promise of lag-free audio with headphones that lack that codec. We make no numeric latency claim for either model. Avantree documents aptX support for Relay, but the correct troubleshooting path still depends on the connected headphones and active mode.

Before travel	Why it changes the choice	What to check
Seat has its own Bluetooth pairing	An external transmitter may be unnecessary	Aircraft/seat instructions for the actual flight
Single versus dual-prong audio jack	Physical adapter may be needed	Jack shape and exact package contents
Two listeners	Both pairs must connect and receive sound	Pair in advance using a suitable 3.5mm source
USB-only port	Charging alone does not establish audio capability	Use the documented audio output path
Airline use	Product compatibility does not grant permission	Current carrier and crew instructions

Budget for the complete audio kit

Setup	Include in the total; current prices unknown	Drawback
One headphone pair	Transmitter, charging cable and any jack adapter	Two-pair capability may add no benefit
Shared listening	Both charged headphones and transmitter	Pairing/codec behavior can differ between pairs
Dual-prong seat	Correct adapter or confirmed package	Avoid buying two adapters unintentionally
Carrying one small pouch	Plug protection and cable storage	Published size does not prove pouch fit

Compare checkout totals for the exact package rather than using an unsupported budget band. Our travel headphone guide covers the separate fit-and-carry decision, and the tech pouch guide helps organize the adapter and charging cable. Neither establishes permission for use on a particular airline.

Decide whether you need a reconnect or a full memory reset

For a two-listener trip, resetting the transmitter has a different consequence from connecting a headphone pair. Twelve South’s AirFly reset guidance, checked October 22, 2026, says to power on Pro 2 and hold PAIR 1 for four seconds. This clears every remembered pairing and puts Pro 2 back into pairing mode.

Situation	Decision before using reset	What to prepare
One familiar pair is not connected	Check the source, mode and normal pairing setup first	Do not assume a full memory wipe targets only that listener
You deliberately want to clear remembered headphones	Use the Pro 2-specific documented reset	Have both intended headphone pairs available to set up again
You are borrowing an older AirFly Pro	Read that exact model’s reset paragraph	The older model’s side-button instructions are not Pro 2 controls
Headphones reconnect but sound is delayed	Recheck the codec/mode limits above	A memory reset is not evidence of lower latency

The practical kit implication is time to configure both listeners again. Separate Pair 1 and Pair 2 controls do not make this documented reset a selective deletion of one headphone. Do the setup with your intended headphones and an appropriate audio source before depending on it during a flight.

We have not tested reset reliability, measured setup time or established that it repairs a particular connection fault. The reset article makes no new promise of two-headphone codec behaviour. Keep the selected standard-white Pro 2 package distinct from Deluxe and older AirFly variants; no new adapter or package claim is added here. Current replacement prices remain unknown. A deliberate reset may be worth trying under the manufacturer’s instructions before buying another transmitter, but the seat-jack, charging and headphone-compatibility checks still determine whether the complete kit suits your trip.

Clear Relay’s old listeners before handing it to another traveler

Avantree’s BTTC-218 manual, version 3.1 dated September 11, 2026, checked October 24, describes a full pairing-history clear. Turn Relay on, hold + and − together for six seconds, then look for red and blue lights remaining on together for three seconds. Pair the intended headphones again. This is Relay’s procedure; AirFly’s controls above are different.

Situation	Prepare before clearing history	Tradeoff
Lending Relay to another traveler	Their actual headphones and a suitable audio source	Remembered listeners must be paired again
Sharing with two listeners	Both pairs available for the documented setup sequence	Clearing history is broader than reconnecting one pair
Connected indicator but silence	Check all three volume controls first	A memory wipe does not establish a working audio source

The manual tells users to pair headphones directly with Relay, rather than searching for Relay in a phone’s Bluetooth menu. Temporarily disabling nearby phone Bluetooth can prevent a competing reconnection during setup. These checks may avoid an unnecessary replacement; current replacement costs are unknown. We have not performed this reset or measured whether it fixes any particular fault.

A listening transmitter does not establish a microphone return path

Before choosing AirFly to combine a flight-listening kit and a call kit, separate the two signal directions. Twelve South’s microphone and calls guidance, checked October 31, 2026, says AirFly devices do not support two-way communication or send microphone audio back to the connected source. Receiving sound in your headphones does not validate an outgoing voice path.

Required job	What the AirFly source establishes	Purchase consequence
Listen from a 3.5mm headphone output	Wireless transmission to headphones	Check the seat-jack and pairing requirements above
Speak back through the headphone microphone	No audio-input return path	Do not buy AirFly as a microphone adapter
Use voice chat in a game	Maker excludes two-way chatting	A listening connection is insufficient
Use the same headphones for a later work call	That call needs its own verified phone/computer arrangement	Plan the host and application separately

This also explains why the receive-mode label above is not evidence of full-duplex conversation. Changing which device supplies audio and carrying microphone audio back during a conversation are different requirements. The cited support statement is general AirFly guidance; it does not provide a new mode-by-mode certification for every newly introduced revision. Obtain explicit model evidence before assuming an exception. It does not establish Relay’s microphone behavior either.

For a useful pre-purchase check, sketch the intended source, transmitter, headphones and outgoing voice connection. Mark which part is supposed to receive speech. If that role has no documented component, resolve it before ordering. Our computer-headphone guide describes a separate Sony call-configuration example; it does not make the airplane adapter a call interface.

Budget and drawback: complete adapter and call-accessory totals are unknown. Retaining direct phone/computer calling may avoid a redundant adapter, but verify the exact application and microphone selection. We have not tested calls, game chat or audio quality, and no workaround through a charging cable or different codec is established here.

Bluetooth on a hearing aid does not establish an AirFly connection

November 2, 2026 connectivity research addition: if the intended listener uses hearing aids, resolve that device’s supported audio path before buying an airplane transmitter. The Bluetooth label on a phone app or device specification does not, by itself, prove it can pair directly with the proposed transmitter. This is an accessory-connectivity check, not advice about hearing treatment or device adjustment.

Twelve South’s AirFly hearing-aid support article, checked November 2, says a connection may be possible when the aids support standard Bluetooth rather than BLE and can enter pairing mode without a smartphone app. The company explicitly does not officially support or guarantee that connection. It says aids requiring an app to pair will not work through this described route, and directs users to their hearing-aid manufacturer when compatibility is uncertain.

What is actually established	Decision before buying	Unresolved boundary
The aids pair with a smartphone	Ask their maker about direct transmitter audio for the exact model	Phone connectivity does not prove this path
Pairing requires a phone application	The cited AirFly support route excludes app-required pairing	Buying another jack adapter does not remove that requirement
The device documentation only says BLE	Do not treat that label as the standard-Bluetooth route described by this article	Obtain exact transmitter and listening-device confirmation
Maker confirms a direct pairing mode	Rehearse the exact connection with the selected transmitter	AirFly’s support article still gives no general guarantee

The support page describes a TX-mode pairing attempt using the hearing aid’s own manual. It does not provide a validated compatibility list for all AirFly revisions or hearing-aid models. Its general wording also does not resolve AirFly View’s separately advertised Auracast mode above. Do not turn this older family support statement into either approval or rejection of every possible newer broadcast-audio arrangement. That would need its own exact-device evidence.

For planning, write down the aid model, proposed transmitter model and the audio output on the actual entertainment source. Ask the listening-device maker which direct audio methods that combination supports before purchasing on a family-name promise. If a separate accessory is required, establish its identity and power needs rather than treating a Bluetooth transmitter as an automatic replacement. We have not qualified such an accessory here.

Budget and drawback: current complete-kit prices are unknown. Confirm the connection before paying for a transmitter, adapter or additional charging lead. A functioning seat jack settles only the wired source side; it says nothing about the listening device’s pairing requirements. We have not tested hearing-aid audio, pairing, listening quality or any medical function, and this section approves no specific hearing aid or retailer package.