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 and European regulators promulgate and enforce consumer protections, there are probably fewer “fly 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.”

Which doesn’t mean you have no rights at all when you fly, so read on.

FLIGHT DELAYED

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: Under most U.S.-based airlines’ contracts of carriage, even if you’re flying on a nonrefundable 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,” but U.S. regulations don’t require cash compensation. However, if flying on an aircraft owned by a European airline, even if departing from the U.S., and even if the ticket was bought from a U.S.-based 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.

FLIGHT CANCELED

Scenario: Your flight is canceled.

Recourse: There’s no U.S. regulation that requires compensation, but if your flight is operated by a European-based airline (even if you purchased it from a U.S. airline and even if you’re departing from an airport outside Europe) you are entitled to compensation of up to 600 euros (about $700) unless the airline can prove the cancellation was beyond its reasonable control.

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 Transportation Department. 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).

BUMPED

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. If you arrive two to four hours later, you are entitled to as much as $675 (the actual amount will be up to 200 percent of the applicable one-way fare); or if over four hours later than scheduled, up to $1,350 or 400 percent of the one-way fare. 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 of up to 600 euros (about $700), along with a requirement that airlines pay for hotels and meals if required.

LUGGAGE LOST

Scenario: An airline loses your checked bags.

Recourse: The U.S. Transportation Department requires the airline to reimburse you up to $3,500. 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.

A different set of rules applies for international travel, 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 Transportation Department 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 Transportation Department has ruled, if you buy an airfare from a U.S.-based airline on a code-share flight, the more generous Transportation Department compensation rules apply.

LUGGAGE DELAYED

Scenario: The airline hasn’t declared your bag “lost” yet but it sure didn’t arrive at the luggage carousel when you did.

Recourse: A Transportation Department advisory states that “carriers should remain willing to cover all reasonable, actual and verifiable expenses related to baggage loss, damage or delay” up to the same maximum lost bag compensation limit of $3,500 on domestic flights. For flights operated under the Montreal Convention, the same 1,131 SDR (or $1,858) 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.

SEAT SELECTION

Scenario: Well ahead of the flight, you reserve an aisle seat 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 CHANGED

Scenario: You buy a $130 round-trip fare from New York to Denver on a nonstop 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 nonstop (but now the nonstop fare is $700).

Recourse: You can insist on a refund of the fare. Sometimes persistence pays off if you ask the airline to put you back on the nonstop.

SCHEDULE CHANGED

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 more.

SEATING ISSUE

Scenario: You’re in the dreaded middle seat and a clinically obese passenger sits down next to you, raises the armrest, and spills over into a portion of your seat.

Recourse: While some airlines have language in their contracts stating that they will refuse to transport passengers who cannot fit into a single seat, or require them to buy two seats, these rules are rarely enforced. You can request to be reseated, or to be put on the next flight out, but that’s about it.

TAKEOFF DELAYED

Scenario: You’re stuck on the plane for more than three hours before take off 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.