“If the passenger fails to occupy space which has been reserved for him/her on a Delta flight and Delta fails to receive notice of the cancellation of such reservation prior to the departure of such flight, or if Delta cancels the reservation of any passenger in accordance with any provision of this rule, Delta will cancel all reservations held by such passenger on Delta flights for continuing or return space, provided Delta originally reserved that space.”

Rule 135 then goes on to add, “Delta is not liable when it cancels the reservation of any passenger in accordance with this rule, but:

“1) If such Delta Airlines Reservations was canceled pursuant to paragraph A) of this rule, Delta will take such action as is provided in Rules 35 and 240 (Flight Delays/Cancellations);

“2) If such reservation was canceled pursuant to other paragraphs of this rule, Delta will refund in accordance with Rule 270 (Voluntary Refunds).”

As far as I can tell, Rule 270 makes no provision for a later arrival, including a missed flight due to delays at check-in or security screening. That’s why passengers are advised to get to airports well ahead of the scheduled boarding time. You can read the whole document yourself at http://www.delta.com/content/dam/delta-www/pdfs/legal/contract_of_carriage_dom.pdf to see if you can find anything specific to your situation that is (or isn’t) addressed.

Discount coach tickets (the kind you and I buy probably buy about 99% of the time), are non-refundable, meaning if you decide not to travel, or miss your flight out of your own fault you lose the ticket. Period.

However, there are some things that you can do in order to protect yourself and get to your destination.

First, take a minute to freak out. Then, when you have that out of your system and your wits about you again, take one of these next steps to correct your course.

Next, Call Delta Airlines Phone Number: 800–325–1551 (hopefully before your flight has taken off).

If you miss your flight, you should immediately seek assistance Delta Airlines.

Delta may allow you to fly stand-by on a later flight. Be forewarned: Delta has implemented “same day stand-by” fees.

NOTE: Discount coach tickets (the kind you and I buy about 99% of the time), are non-refundable, meaning if you decide not to travel, or miss your flight out of your own fault you lose the ticket. Period.

Now, these nonrefundable tickets can be changed ahead of time for a $50 fee, plus the difference in the ticket price. Not cheap, but better than losing one ticket and buying an entirely new one. But these changed reservations need to be done in advance. So if you miss your flight, they need to be done at least before the plane has taken off – even if you aren’t on it.

Two-Hour Rule

What happens if you’ve already missed your flight? It happens. Luckily for you, there is a little-known rule in the airline industry that is known as the two-hour rule, or the flat-tire rule. This is an actual policy at US Airways and Southwest as well as several other airlines, but it isn’t publicized.

Essentially, if there are circumstances beyond your control, like a huge accident on the highway en route to the airport, you may get a little extra help. The two-hour rule states that if a passenger arrives within two hours of their missed flight, the airline employee can put you on the next flight with the same airline on standby at no charge. If you miss the last flight of the day, you’ll be standby on the first flight the next day.

Pro Tip: If you have membership status with the airline you’re flying, sometimes you can get a little extra help. Do be sure to mention this. Please note that this is not a requirement for Delta, so if you are professional and even made attempts to call the airline before the flight departed and let them know your situation, you are more likely to have great assistance at the airport. If you feel that you are not getting support by the gate agent, you can also request a supervisor, who normally is wearing a Red Coat. They are normally more sympathetic to your situation and may assist you. Again, you need to maintain your coolness.

One-Way Tickets

If you’re more than two hours late, you’re probably out of luck and getting a new ticket is next up on your agenda. If you’re on the first part of your itinerary, you can’t just buy a one-way ticket rather than paying an expensive change fee. This will usually cancel your whole itinerary. Your best bet is to pay the change fee. However, if you’re on your return flight home and your bags are already ahead of you, getting a cheap one-way ticket is a great solution. Go for it!

The most important thing is not to beat yourself up about missing a flight. It happens to even the most punctual, seasoned traveler. Going with the flow, being flexible and being kind even when you’re stressed out is part of travel and part of life. Take a deep breath and ask for help. You’ll get where you want to go.

source: What to do when you miss your Delta Flight