Fundamentally, to maximize revenue in the real world. A substantial number of people (which varies based on a lot of factors -- route, date, type of ticket purchased, when it was purchased, how it was paid for, etc.) will be no-shows for any given flight.

If the airline only sold as many tickets as there were seats on the aircraft, it is likely a lot of flights would be much less than full. Incremental revenue is the only way airlines make profits, especially since many of the most frequent no-shows are the highest price tickets (fully-changeable coach, or first class, for business travel; if your client wants you to stay for a few extra minutes to close a $20mm deal, you'll take a later flight!). Airlines would thus be even more unprofitable than they already are.

Sometimes, oversales result from last minute flight equipment changes (747-400 downgraded to a 777), cascading failures of other flights (due to weather, mechanical issues, etc. -- while it is rare for most airlines to involuntarily deny boarding to a ticketed passenger to accommodate another passenger from another flight, they will sometimes ask for volunteers, especially during extremely irregular operations). Usually, however, it is due to something breaking the statistical model of overselling on a flight -- maybe a large group is traveling together, or there is a big event at a specific time, or other flights have been canceled and thus people know if they miss this flight they'll be stuck.

Basically, the costs to the airline of an Involuntary Denied Boarding (IDB) or Voluntary Denied Boarding (VDB) are relatively low ($200-1000), so they're willing to operate pretty close to the wire in terms of expected no-shows, especially for routes with a lot of flights. Airlines have experienced pushback from customers and politicians on oversales, and in some markets, are restricted from overselling as much as would be in their financial self-interest. There are also some markets where almost all fares are infinitely flexible, like ex-Kuwait -- for those flights, >50% no-shows happen on some flights!

Being a voluntarily denied passenger can be a great deal, if you're not in a hurry -- I've waited 6h and gotten upgraded to first class (International...) and had a $200 bottle of champagne and some meals in the lounge, plus 75k frequent flyer miles. Making a fuss (while remaining polite and civil) if you are IDB tends to increase your compensation as well.

The big three airlines are, at this point, too big to fail. These three airlines all have huge monopolies over certain parts of the market. If, for example, United were ‘crushed’ tomorrow, the Denver, Houston, and Dulles markets would be severely impacted. As others have pointed out, there is very little chance the Justice Department would approve a merger of any of these remaining carriers. Southwest would take what they want but they aren’t interested in a rapid expansion into the international market. Most likely, the tier two carriers (Jet Blue, Alaska/Virgin, etc) would swoop in and take whatever was left of the domestic share. But that being said, that won’t happen.

The people in these markets have to fly places. They have to fly from Denver to London, Houston to Frankfurt, Dulles to Munich. If people stopped putting up with United’s horrendous customer service and sub par amenities on board, other carriers would slowly start to pick up the slack. You’d take Lufthansa from Dulles to Frankfurt, and at some point Lufthansa would realize their code share is no longer a beneficial business relationship. United’s stock price would go down and their CEO would be forced out. The airline would change and adapt, or it would shrink as others rose.

It really isn’t that different from any other free market company. But it can’t be crushed as much as it can be squeezed and shrunk from its current market position while allowing others to rise.

To book a flight on United Airlines online, you can:

1. Go to united.com
2. Select Book Flight
3. Enter your origin, destination, and dates
4. Search for flights

You can also book a flight on the United app by selecting Book Flight at the bottom of the screen. However, if your credit card billing address is not in the U.S., Guam, or Puerto Rico, you will be redirected to the website to complete your purchase.

You can also use United's interactive map to find flights to different destinations.

You can manage your reservations by going to My Trips. If you booked a trip through a third party, you can save it to your account by selecting Save to my trips while viewing the reservation.

It depends on the fare class of the ticket.

At the most expensive level, should you purchase a fully refundable ticket, you can rebook at no charge. Very few people, other than employees of large corporations whose companies get a big discount, buy this sort of ticket.

Virtually all other tickets carry some kind of change fee. On an international ticket it can typically vary between US$250–450. To find out what the fee is on your ticket, you need to look at the fare rules. This can usually be done on the United website but might be difficult to find. If you don’t mind being placed on hold for a long time, you can call the airline and ask, they will tell you.

In addition to the change fee, you will also have to pay any difference in fare. If fares have gone down, you’ll get a refund of this amount instead.

Most times you will get a better fare (Deal) online, then calling the reservation center. (Also some airline charge a surcharge for using the reservation center)

When you call, The Call Center agent is measured on number of calls per hour s/he can take. They will not spend 20–30 minutes looking for every possible iteration of flights/fares. They will find what you are asking for and give you the options (Restriction) on the fares that show for THAT one. Then its a Yes or No from you,

You can not play 20 questions.. What about if i took the 9am flight… or 11am … with different return options. The Agent will tell you to go look online or on the App, or contact a Travel Agent (would would charge you $50–100 to do the reservation).

Hey there! Grabbing cheap United Airlines tickets is a bit of an art, and I'm here to spill the secrets. So, picture this: you're a savvy traveler, and you've got a few tricks up your sleeve.

First off, timing is key:

• Keep an eye on flash sales and promotions. Airlines, including United, often drop prices during these limited-time events.
• Plan your booking mid-week when airlines tend to release new fares. Tuesdays and Wednesdays are your sweet spots.

Now, let me tell you a little story from my own globetrotting adventures:

• One time, I scored an insanely cheap ticket by being flexible with my travel dates. United Airlines had a last-minute deal for a flight departing on a Thursday night. It was an unexpected getaway, and the fare was unbelievably low. Moral of the story? Be open to spontaneous trips, and you might just stumble upon a travel jackpot.

Now, let's talk about those digits you need to call:

• Dial up [1-800-864-8331] or [𝟏-𝟖𝟑𝟑-𝟒𝟘𝟴-𝟴𝟴𝟵𝟬] – United Airlines' hotline. Sometimes, talking to a real person can unearth exclusive deals that aren't on the website.
• Don't hesitate to call again closer to your travel date. If there are unsold seats, they might just slash prices to fill them up.

Remember, it's a bit like hunting for treasure. Stay sharp, stay flexible, and those cheap United Airlines tickets will be yours for the taking. Happy travels!

It all has to do with the complex confusion that is the modern ticket booking system.

For starters, most airlines are going to charge you a variety of fares when you change your ticket: it’s going to probably cost you $150+ to change your ticket, even if you’re doing all the work yourself online. (You’d think it’d be the opposite - that taking care of that stuff yourself should cost you less versus calling and talking to an agent, but no.) United charges at least $200 for domestic and $400+ to make changes to international flights.

Additionally, there’s factors like seat availability on the flight (are more or less seats available in a given class at time of booking? did somebody with a cheaper seat cancel, leaving a less expensive seat available?). How close are you to the departure date? (supposedly, there is a ‘sweet spot’ of when to book fares based on a variety of factors, but it’s hardly cut-n-dry predictable.)

Then there’s the difference in fares. Most airlines these days do not offer identical fares between the same cities, regardless of time of day flown, etc. No no no, there is a complex set of mathematical equations at work that may cost you hundreds if not thousands more dollars for what is, essentially, the same flight between cities A and B, but in the eyes of the airline are not the same at all. For example: an early Monday morning flight between ‘commuter’ city pairs like Chicago and NYC, Washington and Boston, etc., is going to be loaded with business people. Those are high-demand routes offered by multiple airlines; most of those flights will be flying at or near capacity. On the other end of the spectrum, let’s say you’re flying on Tuesday night or some time on Wednesday between Manchester, NH and Jackson Hole, WY. Probably not a lot of demand for that route, on slower travel days, and you might luck out with an upgrade.

And once you’ve figured out what flight/seat you want to change to, you’re going to have to pay the difference between the original fare and the new one, plus your change fee on top of that.

Also, airlines are hoping that you’ll opt for the more expensive seats to begin with, not upgrade them later, so they’ll do what they can to make the decision favorable towards getting you in that upgraded seat up to begin with. They’d rather have a business cabin filled with full-fare customers than fifty super-economy customers in the back.

All in all, what you can find for fares on any given route at any given time is a crapshoot. Last week, you could’ve bagged a round-trip, top-of-the-line First class fare to Delta in the middle of summer for $2,200. Today that same flight is back to costing thousands more.

So, there’s no specific single reason why fares can change THAT much in a matter of days or even hours.