What recourse do you have when a flight is canceled or delayed, or the airline changes its schedule, or loses or delays a checked bag or bumps you from a flight? Even though the U.S. Department of Transportation (DOT) and European regulators promulgate and enforce consumer protections, there are probably fewer rights than you think, and these vary depending on the country you’re flying within, to or from; which airline you buy your ticket from; and which airline is actually operating the flight.

Delta's contract of carriage, which you agree to when you purchase a ticket, is typically restrictive concerning its obligations to passengers: "Published schedules, flight times, aircraft type, seat assignments, and similar details reflected in the ticket or Delta's published schedules are not guaranteed and form no part of this contract. Delta may substitute alternate carriers or aircraft, delay or cancel flights, change seat assignments, and alter or omit stopping places shown on the ticket at any time. Schedules are subject to change without notice. Except as stated…Delta will have no liability for making connections, failing to operate any flight according to schedule, changing the schedule for any flight, changing seat assignments or aircraft types, or revising the routings by which Delta carries the passenger from the ticketed origin to destination."

As ominous as that sounds, it doesn't mean you have no rights at all when you fly. Here's what you should expect in common airline scenarios. 

Bumping (involuntary denied boarding)

Scenario: The airline sells more fares than it has seats on your flight. Someone's got to stay behind and that someone is you.

Recourse: You may be entitled to cash compensation. If you’re bumped from a domestic U.S. flight and the airline rebooks you to arrive an hour or less from your original arrival time, there’s no compensation. For a one- to two-hour delay, it’s 200% of the one-way fare up to $675; over two hours, it’s 400% of the one-way fare up to $1,350. You’re entitled to receive payment in cash. Do not accept a travel voucher since these often come with restrictions and extra hassle.

For international itineraries, if you're flying on an aircraft owned by a U.S.-based airline, the same compensation levels apply, but the lower amount applies to arriving one to four hours after your original time and the higher amount to over four hours. However, if you're flying internationally on a plane owned by a European-based airline, even if you bought the ticket from a U.S.-based airline under a code-share arrangement, you can also seek compensation under European Union law (EC Regulation 261/2004). It stipulates compensation up to 600 euros (about $700), along with a requirement that airlines pay for hotels and meals if required.

More: Why European airlines give you better consumer protection

Taxiway/runway delays

Scenario: You're stuck on the plane for more than three hours before takeoff or upon landing.

Recourse: If leaving from a U.S. airport, you have the right to request to deplane after your domestic flight has been delayed on the taxiway, tarmac or runway for more than three hours (or four hours if it's an international flight). Some restrictions apply, such as if deplaning you would cause a safety hazard.

Delayed flights

Scenario: You’re off to a wedding, an important meeting or Uncle Sid’s funeral, but your flight is delayed for hours or canceled, and you’re not going to arrive in time, so why go at all? 

Recourse: U.S. regulations don't require cash compensation, but under most U.S.-based airlines’ contracts of carriage, even if you’re flying on a non-refundable ticket you can get your airfare and ancillary fees refunded. Delta, for example, stipulates in its contract that, "in the event of flight cancellation, diversion, delays of greater than 90 minutes, or delays that will cause a passenger to miss connections, Delta will (at passenger’s request) cancel the remaining ticket and refund the unused portion of the ticket."  

If flying on an aircraft owned by a European airline, EU delay rules apply with compensation up to 600 euros (about $700), unless the airline can prove the delay was beyond its reasonable control. If you're flying an airline based in Europe, even if you bought the ticket on a non-European airline and no matter your itinerary, you have special consumer rights. 

Canceled flights

Scenario: Your flight is canceled.

Recourse: There’s no U.S. regulation that requires compensation. As above, if your flight is operated by a European-based airline, you are entitled to compensation of up to 600 euros. 

Lost luggage

The scenario: An airline loses your checked bags.

Your recourse: The U.S. DOT requires the airline to reimburse you up to $3,500 per incident. However, the airline may ask for receipts for claimed items, may depreciate the value of the suitcase and its contents, and will not compensate for electronic items such as cameras, computers, jewelry, or cash except as noted below.

A different set of rules applies for international travel, even if a portion of the trip was on a U.S. airline, and the liability limits may be considerably lower. 

Most foreign airlines follow "Montreal Convention" rules, which limit reimbursement to 1,131 Special Drawing Rights (SDRs), a basket of international currencies whose value changes slightly day by day (at time of writing 1131 SDRs is $1,858). However, the U.S. DOT has stated that an airline that adheres to the Montreal Convention may not refuse to reimburse passengers for electronic equipment, jewelry and other "valuable" items in lost luggage. Furthermore, the DOT has ruled, if you buy an airfare from a U.S.-based airline on a code-share flight (you buy from American Airlines, for example, but the flight is operated by British Airways), the more generous DOT compensation rules (rather than the Montreal Convention limits) apply.

More: Why airline codesharing must die

Delayed luggage

The scenario: The airline hasn't declared your bag "lost" yet but it didn't arrive at the luggage carousel when you did.

Recourse: A U.S. DOT advisory states that "carriers should remain willing to cover all reasonable, actual and verifiable expenses related to baggage loss, damage or delay [emphasis added]" up to the same maximum lost bag compensation limit of $3,500 on domestic flights. For flights operated under the Montreal Convention, the same 1131 SDR (or $1858) compensation for a lost bag also applies to a delayed bag. So if you're attending a meeting and your business clothes are in the delayed bag, then yes you can buy a replacement and be reimbursed. In past years, airlines have offered $25 or $50 to buy a toothbrush and toiletries, but that is no longer acceptable (the U.S. DOT has heavily fined airlines, both domestic and foreign-owned, for this practice).

You buy the wrong flight

Scenario: You hit the "buy" button on the airline's website and immediately realize you chose the wrong dates or destinations, or buy two seats when you only wanted one.

Recourse: As long as you make the change within 24 hours and the flight leaves at least a week from the time of purchase, you have the right to either cancel your fare or rebook different dates, according to the U.S. DOT. This rule applies to all carriers (American may also allow you to put a fare on hold up to 24 hours for free without paying for it).

Seat selection

Scenario: You reserve an aisle seat in advance but on the day of the flight you’re moved to a middle seat.

Recourse: None. Airlines reserve the right to assign you to any seat they choose. They can even put you in an economy-class seat if you paid for business class.

Routing changes

Scenario: You buy a $130 round-trip fare from New York to Denver on a non-stop flight. A few weeks before departure, the airline informs you that you’re now flying with a connection and with different departure and arrival times, even though it still flies the route non-stop (but now the nonstop fare is $700). 

Recourse: You can insist on a refund of the fare, but you have no contractual or governmental right to be rebooked on the original flight. However, sometimes persistence pays off if you ask the airline to put you back on the non-stop.

Schedule changes

Scenario: This is different from a flight delay. For example, you booked a flight in June for a trip in December, and in October the airline informs you that your flight will leave at 11 a.m. rather than 6 a.m. But that means you’ll miss an important meeting. Or the airline changes its schedule from daily service to five times a week, which means you will be forced to spend an extra night at your destination at your own expense.

Recourse: This is a tough one. Passengers in these situations can apply for a refund and are free to find flights on a different airline, although alternate flights might cost considerably more.

George Hobica is the founder of Airfarewatchdog.com. Airfarewatchdog features the best airfares on thousands of routes verified by a team of expert fare analysts.