Does background reading work in aeroplane mode?
Reading the tag usually works, since NFC is a separate radio from the ones aeroplane mode targets and behaviour varies by device. What fails is everything after it, because a web address needs a network and aeroplane mode is precisely the absence of one.
A separate radio
Aeroplane mode targets the radios that communicate over distance: cellular, and by default the wireless networking and short range links.
NFC works over centimetres and is a distinct radio from those. Some devices leave it enabled in aeroplane mode and some do not, and it can usually be switched back on independently where it was disabled.
So the honest answer is that reading a tag often works, and it is device dependent enough that testing your own phone is the reliable route.
What fails is what comes after
This is the part that matters and the part people miss.
A tag holding a web address is a pointer. Reading it succeeds, the phone offers to open the address, and the address cannot be reached because there is no network.
From the user's position the tag failed. From the tag's position it worked perfectly and delivered exactly what it held.
Content stored on the tag itself behaves differently. Text, contact details and anything the phone can act on locally all work with no network at all.
Device behaviour varies
Whether NFC survives aeroplane mode is a manufacturer decision rather than a standard, and it has changed across versions.
The practical test takes ten seconds: switch aeroplane mode on, present a tag you know works, and observe.
Do it on the phones that matter to your deployment rather than reasoning about it, since a rule established on one device does not transfer.
And note that a phone can have NFC available while a power saving mode active at the same time restricts it, which produces the same symptom for a different reason.
Designing for no network
Aeroplane mode is one case of a general problem: taps where there is no coverage. A basement, a warehouse, a ship, a venue at capacity.
Where that is a real possibility, content on the tag beats a pointer, and the tag has to be sized for it.
The hybrid is underused: essential information as text, and a link alongside for anyone with coverage. It costs memory and removes the worst failure.
And where a link is the right answer anyway, say so on the tag. A visitor who knows a page will open understands why nothing happened when they had no signal.
Frequently asked questions
Is NFC disabled by aeroplane mode?
It varies by device and version, and where it is disabled it can usually be switched back on independently. Test the phone that matters to you.
Why does my tag do nothing on a plane?
Most likely the tag read fine and the address it holds could not be reached. Reading and reaching the destination are separate steps.
Does a text tag work offline?
Yes. Content stored on the tag needs no network, which is the argument for putting it there when coverage is uncertain.
Can I use NFC on a flight?
The reading itself is a centimetre range interaction, and the applicable rules are the airline's rather than a technical question.