Why do some airplane headphones have 2 Jacks instead of 1 everywhere else?


Every time I go on a plane it is about a 50/50 chance between headphones with 1 jack or 2.

Why do some have 2 jacks? What is the function of it?

In: 21

I believe it converts two mono lines into a stereo output.

If you look at the end of a jack, you’ll see an oddly shaped tip, sometimes a few rings, and then the shaft. Mono lines (where the audio doesn’t differentiate between left and right) have just a tip, and a shaft. One sends the audio, and one is the neutral return to complete the circuit. Airplanes have two of these mono tip shaft setups. (Sometimes)

A stereo jack has tip, ring, and shaft, the ring allowing for another channel of audio

Airplane adaptors combine two mono tip shaft outputs, into one tip, ring, shaft stereo, which is what most headphones nowadays are.

Modern day phones, have tip, ring ring, shaft.

This means they can send left and right ear audio separately, and power a microphone.
This is why your headphone mic works on phones but not pcs, because pcs generally have a separate mic input.

Airlines used to take advantage of these fact that regular headphones only used one line in order to sell you adapters or headphones that use two lines in flight. Classis captive market cash grab.

The funtion is that you don’t take the earphones with you when you leave because they are useless to you. Intentional incomatibility.

3 bucks for headphones, or just the adapter. I know some airlines tried to rent the headphones and to be honest didn’t fly in US much back then more Europe Asia
The reason for two Jack’s was because if it was a normal 3.5mm socket, everyone would just take them