When checking in online today for an Air Canada flight, I was informed that my boarding pass had to be printed rather than shown on the screen, as AC doesn't support "mobile" boarding passes for that airport. However in theory there's absolutely no difference between a QR code printed on a piece of paper and one shown on a display. So if I rocked up to Las Vegas airport with just a "paper" boarding pass on my screen, would I really be refused entry by the TSA?

In short, as of 2018 is there ever really a need to print a boarding pass in the US, regardless of what the airline says about it?

  • Comments are not for extended discussion; this conversation has been moved to chat. – JonathanReez Aug 15 at 19:40
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  • @R.. see this meta post. Generally its okay to move all the comments to chat. If more selective modding is needed I leave it up for other mods to deal with. – JonathanReez Aug 16 at 0:52
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up vote 54 down vote accepted

Phone screens are not like printed paper, even if they seem similar to the naked eye.

A scanner for paper is designed to illuminate paper and read the reflection. So the scanner could send a specific wavelength, and expect the same. Phone screen could not deliver such wavelength (it must just have good R, G, B), but pretty free on how to choose the wavelength distribution. Old scanner used in particular deep red or infrared. Phone will not have infrared transmission on white.

Scanner could choose the intensity, but a phone reader not.

Additionally white on paper is continuous, but a phone screen is not, you will have lots of dark surfaces (especially if you filter e.g. only red). It is above our eyes' resolution, so not a problem for us, but a scanner should have a signal filter, not to see such black, but still see the black dots.

In facts, I have had many more problems when scanning tickets on a phone (in general, not only at airports) than on paper.

Modern scanners have a camera and these cameras are much more sensitive (on low screen light), so the problem is disappearing.

So, it is risky. If you have a "retina"-like phone, with many pixels, and a very bright screen, it will be less problematic, but with a cheap phone you may have problems. On the other hand, good phones have better colour (and "LED" pixels), better colours means more saturated colours, so less wavelengths. So it is your risk.

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    But other airlines departing from the same airport do support "mobile" boarding passes, so it shouldn't be an issue. – JonathanReez Aug 13 at 13:11
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    The scanners used by Air Canada at the gate may be old. Other airlines and the TSA aren't their problem. – Steve Smith Aug 13 at 13:17
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    If they have assigned gates, check-in counters, etc, they could have their own equipment which may not be compatible while other airlines may be OK. Or the equipment may not be the same at all gates (e.g. from one terminal to another). Best case, their systems are just not up to date (and they err on the side of caution). But if you get to the airport and somewhere along the way they can't scan your mobile, it's going to cause issues... – jcaron Aug 13 at 13:17
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    I've had problems with model QR codes because I keep my screen dim. Some readers can't handle that. There's nothing like slowing down a line while I fumble trying to increase my phone screen's brightness! – mkennedy Aug 13 at 18:15
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    @mkennedy apps like Apple Wallet or Google Pay crank up the brightness to the max when displaying QR codes (so if you can save the boarding pass to these, that might make life slightly easier). – muru Aug 14 at 4:04

There is one reason I can imagine - if it is an international flight, they are required to check your documents to make sure you are allowed to enter the target country.

Many airlines do that by writing 'docs ok' or some other shorthand on the paper boarding pass (some use a stamp, as once you know the method, you could just write yourself 'docs ok').
With a online boarding pass, they cannot write that on the paper. That could be the reason they require paper boarding passes.

I have seen the same with Lufthansa flights to Europe from Orlando and Newark; if you use the mobile boarding pass, they ask you for your documents (again) at the boarding door (more or less annoyed).

  • Southwest doesn't allow mobile boarding passes (or even mobile-printed ones) when there are children on the same itinerary, in my experience; I always assumed it was for this reason, essentially, as the check-in agent will often write something on the children's boarding passes. That said, if they allowed a paper boarding pass to be printed at home, it doesn't necessarily validate this particular suggestion, given you're still skipping the check-in desk. – Joe Aug 13 at 15:59
  • @Joe - if there is more than one traveler on a Southwest reservation you don't get mobile boarding passes. It is not a question of the age(s) of the travelers, sadly... – Jon Custer Aug 13 at 17:09
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    @JonCuster , Southwest finally enabled this just this month! – Aganju Aug 13 at 17:34
  • @Aganju - interesting - I was not offered that option yesterday. I got an offer to print them on my own computer, but not a mobile pass. – Jon Custer Aug 13 at 17:37
  • @JonCuster Hmm, interesting. I suppose I haven't tried with only adults. Thanks! – Joe Aug 13 at 18:25

Yes. Printable boarding passes work. Phone boarding passes are unreliable, because they require you be logged into the airline "app" and that login expires for security reasons. Or the user has to find his email. Or the user cant get WiFi and for some reason the process to get that BP requires it. Or the battery is flat.

On cell signal, airports are a relatively good case, since they are open, airy, spread out and on the surface. I can tell you in the bowels of Union Station, cellphone signal isn't a possibility (which also means the free wifi on the train cars has no uplink). Amtrak had not thought to extend wired WiFi (least of all free Wifi) to the platforms proper. As it happened, I had the foresight to shoot a screencap of the boarding pass, and I switched to my photos app and presented the screencap.

Anyway, back to our airport. You will have quite a lot of tech snafu's like this. Forgetting their app password. Frantically searching their emails. Or their battery dying. Or whatever. People being peolle, this wont happen in the queue, it'll happen when they are talking to the agent. And it really, reaally slows down the line. To an airline, flow is money. If you require printed tickets, all that is solved.

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    what is "wired WiFi", I wonder? – Igor Skochinsky Aug 13 at 16:11
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    As distinct from cellular-uplink WiFi like airplanes and trains have. I don't know if you're familiar with the underlying technology of WiFi, but (planes/trains/ferries notwithstanding) it consists of terrestrial wired Internet brought to antennas which then serve the WiFi signal. Some wireless relaying is possible, that's been true even since the days of Ricochet/Metricom, so you can have nodes with nothing but a power connection. But only a limited number of relay hops are possible before it must reach a wired network point. – Harper Aug 13 at 16:23
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    Note that iOS products come with an app called "Wallet" which can, among other things, be used to store some airlines' boarding passes locally on your phone so that network connectivity isn't needed. The ability (and method) to do this depends on the carrier, though, and I don't know that Amtrak has implemented this system. – Michael Seifert Aug 13 at 18:01
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    @MichaelSeifert Every smartphone should be capable of taking a screenshot of what's currently displayed on the screen, saved to the device (either internal memory or a removable SD card). Displaying a screenshot isn't any different to displaying the QR code from the airline's app, so you don't need something like the iOS wallet to solve that problem - just take a screenshot of it ahead of time. – Anthony Grist Aug 14 at 15:32
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    @MichaelSeifert regardless, not everyone's phone is late model iOS. The pinch point here is not Whether a technical soluion exists; it's whether the airline experiences their line moving fast enough they feel they can trust the people to use them. Random flyers are not tech geeks like ourselves. It does not help the airline when 90% of people don't use solutions they have access to. Regardless, this is no place for a debate on available solutions, because that instantly devolves into a debate on how to get people to use them. – Harper Aug 14 at 19:46

My guess would be simpler: paper is faster to scan during the boarding process.

TSA certainly isn't going to be the issue here, by the way (they'll let you in; they probably don't know the individual airlines' policies, at least the individual agent likely wouldn't); it's the gate agent who'd have the issue with it.

While much of the time phone screens are fine, sometimes they just don't scan; they take an extra 30 seconds to a minute sometimes to scan for people whose screens don't have sufficient contrast or brightness, or whose phones are overly smudged, or don't have it up when they get to the gate. Paper will be faster on average, so they may well be simply disallowing them to speed boarding.

  • Paper doesn't always scan the first time either. Paper gets folded, smudged, and the pass could have been printed out while the printer was running low on toner. – Abigail Aug 15 at 15:39
  • @Abigail Sure, but from my experience way more people have trouble with phones than paper. – Joe Aug 15 at 15:42

It doesn't answer the broader question, but at least in this instance Air Canada agrees that there isn't a difference:

screenshot of text conversation between customer and representative (transcript follows)

Transcript of screenshot

Q: Is it necessary to print the boarding pass when departing Las Vegas airport to Vancouver? Or can I just show it on my phone screen?

A: Hello you may definitively have your eBoarding Pass on your cellphone. /Alex

So its probably an issue with their site not being up to date.

It's Air Canada's aeroplane, so they get to make the rules about who is allowed on board. If their rule is that you don't get on without a paper boarding pass, then you need a paper boarding pass if you want to fly. (Other answers have explained why they might want to make such a rule).

For U.S. airports in general? No, there's no difference and mobile boarding passes are definitely supported. TSA won't care and likely hundreds of thousands of people go through TSA security with them every single day, including at LAS. I've being going through TSA checkpoints with mobile boarding passes for years and it's never been any trouble.

If there is any difference, it has nothing to do with US airports in general or TSA, but only Air Canada and possibly only Air Canada at that particular airport. If there's any problem, it would be with Air Canada scanning your boarding pass at the gate to board, not with TSA scanning it to enter security.

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