score:33
It’s probably difficult to give an exhaustive list of all the reasons, but here are some:
I would say the most common case is probably lack of proper documentation (passport, visas, health certificates).
You should use the IATA travel centre to check for requirements for both destination and transit countries.
You should do so even before you book. You should probably also check on a regular basis that it doesn’t change. In Covid times this has changed A LOT, often with very little notice.
Upvote:1
You have the same name as another passenger on the flight, and someone thinks the some person booked twice by mistake and removes one booking. One perfectly legal John Smith goes ahead, and another perfectly legal John Smith is stuck.
Upvote:2
The airline staff at the check-in counter thinks that the passenger's passport is damaged. I've had a case where my passport was really in near pristine condition and still got denied by 1 airline (the 2 other airlines I asked right after as well as my consulate when I replaced my passport soon after we're extremely surprised I had been refused boarding for that reason).
Upvote:3
Another reason: the check-in/gate agent believes that you lack the proper documentation for your journey: transit countries, the destination country, etc. As far as I understand, they never try to interpret legal documents on embassy's website and instead rely on internal airline's instructions. Instructions may or may not be based on IATA Timatic. There may be "oral instructions from the country's border control", whatever that means. There may be airline-specific blanket bans on specific nationals to enter a specific country.
Examples are:
Moreover, sometimes the airline may claim that they're not responsible for the denied boarding as it outsourced checks to some local company (see the last bullet above).
I'm not aware of any way to check internal airlines policies. Calling or writing a letter typically results in a general "you have to ensure that you have all the proper documentation and we do not provide personal advice" response. You may even show up in the airport few days in advance and try to find the supervisor responsible for visa checks and ask them to clarify the situation for you, but there are no guarantees that the same supervisor will be watching for your check-in.
The only thing that may work is to check-in in person, at least a few hours earlier than you typically do, be well-equipped with Timatic printouts/printouts from embassy's website/ambassador's phone/phones of the immigration control in your destination's airport, and hope that the supervisor actually bothers to call/email the immigration control with all the details, and that the immigration control responds in time for you to catch the flight.
Upvote:4
For example:
https://www.nytimes.com/2017/03/26/us/united-airlines-leggings.html
https://onemileatatime.com/southwest-airlines-woman-lewd-outfit/
This is potentially more of a problem with international travel as some countries have much stricter cultural norms (for lack of a better term) than others - i.e., you may fly from country A where "anything goes" to country B that is far more conservative. And even transit can be an issue - you may be flying from A to C where the clothing tends to be similar (and more revealing) but transit through the airport in B where things are more strict. But the problem really could happen anywhere.
Reminds me of an old joke: https://www.math.ttu.edu/~pearce/jokes1/joke-030.html
Upvote:4
There is another general but rarely used one: The pilot thinks you will be a danger to the plane, crew or passengers. This is unlikely unless you fall under one of the other criteria (intoxicated, abusive, unruly or making threats) but pilots have very wide discretion to remove passengers.
Upvote:5
I haven't been denied ever in any of my flights. I usually follow these
Elaboration on EU: Even though Shengen visa is issued by one country, it is valid for travel to all member states without further checks. However, to prevent visa shopping, the country you are supposed to be spending most time in according to plan issues you a visa. If you change that plan, there are risks that you may be denied entry. There are instances that hotels reports to immigration authority when accommodation is cancelled. So, its essential to more or less, stick to the plan.
Upvote:7
One more:
You booked through a third-party (consolidater, like expedia or gotogate or edreams, etc), and they messed up your booking, or cancelled it (maybe because the scheduled flight times moved 5 minutes; happened to me).
Upvote:15
A few more that are not the passengers fault.
Some of these issues can obviously be resolved but not always in time for making the original flight.