HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news

Cheap flights from Austin to San Antonio (AUS - SAT) from $134

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 6/18. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
AUS — SAT
juin 2 — juin 91
From?
To?
dim. 6/2
dim. 6/9
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Cheap flight deals from Austin to San Antonio

Discover tips and strategies to find the most affordable flight options for your journey from Austin (AUS) to San Antonio (SAT). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated mai 28, 2024.

Popular in

May

Cheapest in

February

Round-trip from

$291

One-way from

$159
High demand for flights, 26% potential price rise
Search Deals
Best time to find cheap flights, 49% potential price drop
Search Deals
From Austin Bergstrom to San Antonio
Search Deals
One-way flight from Austin Bergstrom to San Antonio
Search Deals

What is the cheapest day to fly round-trip from Austin to San Antonio?

Flying to your destination on a Wednesday can be more expensive, but this shouldn’t discourage you from finding affordable options to get to San Antonio. Check prices with Cheapflights to find a great deal for your trip.

What is the cheapest month to fly from Austin to San Antonio?

Flights from Austin to San Antonio lean towards being more expensive in May. Prices are generally better when you fly from Austin to San Antonio in February, with the cheapest ticket starting at $286.

When is the cheapest time to fly from Austin to San Antonio (AUS - SAT)?

Unlike in the afternoon, when flights are generally more expensive, you can save up to 13% on flights from Austin to San Antonio by exploring options for tickets in the morning.

Cheap United Airlines flights from Austin to San Antonio

Explore cheap flight options specifically provided by United Airlines for the route between Austin and San Antonio. Find affordable fares and compare prices with other airlines to secure the best deal for your journey. Over the last 7 days, Cheapflights users made 2,696,634 searches. Data last updated mai 28, 2024.
Consider these cheap United Airlines flights we've found departing from Austin to San Antonio. Deals update often to give you more flight options matching your criteria
mar. 6/118:50 amAUS - SAT
1 stop15h 09mUnited Airlines
sam. 6/155:37 amSAT - AUS
1 stop18h 21mUnited Airlines
Deal found 5/27$541
jeu. 6/275:15 amAUS - SAT
1 stop10h 08mUnited Airlines
lun. 8/52:05 pmSAT - AUS
1 stop20h 01mUnited Airlines
Deal found 5/28$640

Cheap Spirit Airlines flights from Austin to San Antonio

Explore cheap flight options specifically provided by Spirit Airlines for the route between Austin and San Antonio. Find affordable fares and compare prices with other airlines to secure the best deal for your journey. Over the last 7 days, Cheapflights users made 2,696,634 searches. Data last updated mai 28, 2024.
Some of the lowest-priced Spirit Airlines flights we've found at this time heading from Austin to San Antonio. Deals frequently update to provide users with more options.
mar. 6/254:49 pmAUS - SAT
1 stop9h 06mSpirit Airlines
mar. 7/25:10 amSAT - AUS
1 stop10h 48mSpirit Airlines
Deal found 5/28$229
mar. 6/254:49 pmAUS - SAT
1 stop9h 06mSpirit Airlines
mar. 7/25:10 amSAT - AUS
2 stops28h 00mSpirit Airlines
Deal found 5/28$274
mar. 6/254:49 pmAUS - SAT
3 stops23h 46mSpirit Airlines
mar. 7/25:10 amSAT - AUS
1 stop10h 48mSpirit Airlines
Deal found 5/28$311
mar. 6/254:49 pmAUS - SAT
3 stops23h 46mSpirit Airlines
mar. 7/25:10 amSAT - AUS
2 stops28h 00mSpirit Airlines
Deal found 5/28$357
mar. 6/254:49 pmAUS - SAT
3 stops23h 46mSpirit Airlines
mar. 7/25:21 amSAT - AUS
3 stops26h 55mSpirit Airlines
Deal found 5/28$401
dim. 6/92:27 pmAUS - SAT
1 stop11h 28mSpirit Airlines
lun. 6/106:45 amSAT - AUS
2 stops26h 25mSpirit Airlines
Deal found 5/28$417
mar. 6/114:49 pmAUS - SAT
3 stops26h 50mSpirit Airlines
sam. 6/1510:09 pmSAT - AUS
2 stops15h 28mSpirit Airlines
Deal found 5/27$449
mar. 6/114:49 pmAUS - SAT
1 stop9h 06mSpirit Airlines
sam. 6/1510:09 pmSAT - AUS
2 stops15h 28mSpirit Airlines
Deal found 5/27$451
mar. 6/114:49 pmAUS - SAT
2 stops23h 46mSpirit Airlines
sam. 6/1510:09 pmSAT - AUS
2 stops15h 28mSpirit Airlines
Deal found 5/27$461

Cheap Austin to San Antonio flights in May & June 2024

Find cheap flight options from Austin to San Antonio specifically for the months of May and June 2024. Explore affordable fares based on user searches. Over the last 7 days, Cheapflights users made 2,696,634 searches. Prices were last updated on mai 28, 2024.
These are some of the best deals we've found on flights to San Antonio in 2024 at this time. If these deals don't appeal to you, be sure to come back soon for more options.
mar. 6/254:49 pmAUS - SAT
1 stop9h 06mSpirit Airlines
mar. 7/25:10 amSAT - AUS
1 stop10h 48mSpirit Airlines
Deal found 5/28$229
mar. 6/254:49 pmAUS - SAT
1 stop9h 06mSpirit Airlines
mar. 7/25:10 amSAT - AUS
2 stops28h 00mSpirit Airlines
Deal found 5/28$274
mar. 6/254:49 pmAUS - SAT
3 stops23h 46mSpirit Airlines
mar. 7/25:10 amSAT - AUS
1 stop10h 48mSpirit Airlines
Deal found 5/28$311
mar. 6/254:49 pmAUS - SAT
3 stops23h 46mSpirit Airlines
mar. 7/25:10 amSAT - AUS
2 stops28h 00mSpirit Airlines
Deal found 5/28$357
mar. 6/254:49 pmAUS - SAT
3 stops23h 46mSpirit Airlines
mar. 7/25:21 amSAT - AUS
3 stops26h 55mSpirit Airlines
Deal found 5/28$401
dim. 6/92:27 pmAUS - SAT
1 stop11h 28mSpirit Airlines
lun. 6/106:45 amSAT - AUS
2 stops26h 25mSpirit Airlines
Deal found 5/28$417
dim. 6/98:05 pmAUS - SAT
1 stop14h 35mMultiple Airlines
lun. 6/1010:46 pmSAT - AUS
3 stops34h 24mMultiple Airlines
Deal found 5/28$438
dim. 6/98:05 pmAUS - SAT
1 stop14h 35mMultiple Airlines
lun. 6/1010:46 pmSAT - AUS
1 stop17h 12mMultiple Airlines
Deal found 5/28$444
mar. 6/114:49 pmAUS - SAT
3 stops26h 50mSpirit Airlines
sam. 6/1510:09 pmSAT - AUS
2 stops15h 28mSpirit Airlines
Deal found 5/27$449

Austin to San Antonio 2024 flight deals

Discover exclusive flight deals for travel between Austin and San Antonio in 2024. Find excellent offers based on user searches. Over the last 7 days, Cheapflights users made 2,696,634 searches. Data last updated mai 28, 2024.
These are some of the best deals we've found on flights to San Antonio in 2024 at this time. If these deals don't appeal to you, be sure to come back soon for more options.
mar. 6/254:49 pmAUS - SAT
1 stop9h 06mSpirit Airlines
mar. 7/25:10 amSAT - AUS
1 stop10h 48mSpirit Airlines
Deal found 5/28$229
mar. 6/254:49 pmAUS - SAT
1 stop9h 06mSpirit Airlines
mar. 7/25:10 amSAT - AUS
2 stops28h 00mSpirit Airlines
Deal found 5/28$274
mar. 6/254:49 pmAUS - SAT
3 stops23h 46mSpirit Airlines
mar. 7/25:10 amSAT - AUS
1 stop10h 48mSpirit Airlines
Deal found 5/28$311
mar. 6/254:49 pmAUS - SAT
3 stops23h 46mSpirit Airlines
mar. 7/25:10 amSAT - AUS
2 stops28h 00mSpirit Airlines
Deal found 5/28$357
mar. 6/254:49 pmAUS - SAT
3 stops23h 46mSpirit Airlines
mar. 7/25:21 amSAT - AUS
3 stops26h 55mSpirit Airlines
Deal found 5/28$401
dim. 6/92:27 pmAUS - SAT
1 stop11h 28mSpirit Airlines
lun. 6/106:45 amSAT - AUS
2 stops26h 25mSpirit Airlines
Deal found 5/28$417
dim. 6/98:05 pmAUS - SAT
1 stop14h 35mMultiple Airlines
lun. 6/1010:46 pmSAT - AUS
3 stops34h 24mMultiple Airlines
Deal found 5/28$438
dim. 6/98:05 pmAUS - SAT
1 stop14h 35mMultiple Airlines
lun. 6/1010:46 pmSAT - AUS
1 stop17h 12mMultiple Airlines
Deal found 5/28$444
mar. 6/114:49 pmAUS - SAT
3 stops26h 50mSpirit Airlines
sam. 6/1510:09 pmSAT - AUS
2 stops15h 28mSpirit Airlines
Deal found 5/27$449

One-way flights to San Antonio from Austin

Search for one-way flight options from Austin to San Antonio. Find affordable one-way fares based on user searches. Compare prices and availability to plan your one-way journey according to your preferred dates and budget. Over the last 7 days, Cheapflights users made 2,696,634 searches. Data last updated mai 28, 2024.
Users in need of a one-way flight from Austin to San Antonio can choose from these deals. Those needing a return flight from Austin to San Antonio can use the search form above.
mar. 6/184:49 pmAUS - SAT
1 stop9h 06mSpirit Airlines
Deal found 5/27$134
jeu. 6/277:48 pmAUS - SAT
1 stop12h 35mUnited Airlines
Deal found 5/28$159
mar. 6/1810:00 amAUS - SAT
2 stops26h 58mSpirit Airlines
Deal found 5/27$165
ven. 6/1411:53 amAUS - SAT
1 stop14h 02mMultiple Airlines
Deal found 5/28$171
ven. 6/1410:03 pmAUS - SAT
2 stops19h 54mSpirit Airlines
Deal found 5/28$172
mar. 6/44:49 pmAUS - SAT
3 stops26h 50mSpirit Airlines
Deal found 5/27$177
mar. 6/254:49 pmAUS - SAT
2 stops23h 46mSpirit Airlines
Deal found 5/28$179
mar. 6/44:49 pmAUS - SAT
1 stop6h 54mSpirit Airlines
Deal found 5/27$184
ven. 6/710:03 pmAUS - SAT
2 stops19h 54mSpirit Airlines
Deal found 5/27$200

Find flights from Austin to San Antonio within your budget

Customize your flight search to find flights from Austin to San Antonio that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,696,634 searches. Data last updated mai 28, 2024.

Fly from

Any airport

Fly to

Any airport

Budget

$229 - $541

Route

Depart

Return

Price

Austin BergstromSan Antonio

AUS - SAT

AUSSAT

Austin Bergstrom

mar. 6/25

1 stop9h 06m

San Antonio

mar. 7/2

1 stop10h 48m

$229

Austin BergstromSan Antonio

AUS - SAT

AUSSAT

Austin Bergstrom

mar. 6/25

1 stop9h 06m

San Antonio

mar. 7/2

2 stops28h 00m

$274

Austin BergstromSan Antonio

AUS - SAT

AUSSAT

Austin Bergstrom

mar. 6/25

3 stops23h 46m

San Antonio

mar. 7/2

1 stop10h 48m

$311

Austin BergstromSan Antonio

AUS - SAT

AUSSAT

Austin Bergstrom

mar. 6/25

3 stops23h 46m

San Antonio

mar. 7/2

2 stops28h 00m

$357

Austin BergstromSan Antonio

AUS - SAT

AUSSAT

Austin Bergstrom

mar. 6/25

3 stops23h 46m

San Antonio

mar. 7/2

3 stops26h 55m

$401

Austin BergstromSan Antonio

AUS - SAT

AUSSAT

Austin Bergstrom

dim. 6/9

1 stop14h 35m

San Antonio

lun. 6/10

3 stops34h 24m

$438

Austin BergstromSan Antonio

AUS - SAT

AUSSAT

Austin Bergstrom

dim. 6/9

1 stop14h 35m

San Antonio

lun. 6/10

1 stop17h 12m

$444

Austin BergstromSan Antonio

AUS - SAT

AUSSAT

Austin Bergstrom

dim. 6/9

2 stops19h 17m

San Antonio

lun. 6/10

3 stops34h 24m

$488

Austin BergstromSan Antonio

AUS - SAT

AUSSAT

Austin Bergstrom

mar. 6/11

1 stop15h 09m

San Antonio

sam. 6/15

1 stop18h 21m

$541

Flights are sorted by cheapest first

Deals found on 5/28

When is the cheapest time to fly from Austin to San Antonio?

Use this chart to determine the cheapest time to fly round-trip from Austin to San Antonio. Price data was last updated on May 26, 2024.
Morning
Noon
Afternoon
Evening
All times are departure.
Travelers seeking maximum savings on their Austin to San Antonio flight should consider departing on Wednesday mornings when fares are most often at their lowest. Wednesday mornings flights should be avoided if possible as fares are typically the most expensive at this time.
Search Deals

Best time to book a flight from Austin to San Antonio

Have a flexible travel schedule? Discover the best time to fly to San Antonio from Austin with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Temperature and rainfall in San Antonio by month

Plan your trip to San Antonio by taking into account the average temperature and rainfall totals by month.

SAT

Temperature

51.8 - 84.2 °F

Reviews of airlines servicing San Antonio

Get insights into the airlines that provide service to San Antonio. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to San Antonio. Reviews last updated mai 28, 2024.
Read through reviews of airlines operating flights from Austin to San Antonio, such as United Airlines and Spirit Airlines. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.
United Airlines
7.4
Good
10,799 reviews
Check prices

Comfort

7.2

Overall

7.4

Boarding

7.7

Crew

8.1

Entertainment

7.1

Food

6.7

Reviews

1 / 10

Flight from shv was great. My connecting flight was canceled though. Had to stay overnight in airport

United Airlines
7.4
Good
10,799 reviews
United Airlines
7.4
Good
10,799 reviews
Check prices

Comfort

7.2

Overall

7.4

Boarding

7.7

Crew

8.1

Entertainment

7.1

Food

6.7

Reviews

1 / 10

Flight from shv was great. My connecting flight was canceled though. Had to stay overnight in airport

Spirit Airlines
6.4
Okay
8,615 reviews
United Airlines
7.4
Good
10,799 reviews
Check prices

Comfort

7.2

Overall

7.4

Boarding

7.7

Crew

8.1

Entertainment

7.1

Food

6.7

Reviews

1 / 10

Flight from shv was great. My connecting flight was canceled though. Had to stay overnight in airport

Related info for your journey

Find useful and relevant information for your journey from Austin to San Antonio. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • Can I find flights from Austin to San Antonio for under $300 on Cheapflights?

    Yes, there are multiple flights from Austin to San Antonio for under $300. The cheapest flight booked recently is on Spirit Airlines for just $229, but on average you can expect to pay $424.

  • What are the cheapest airlines flying from Austin to San Antonio round-trip?

    According to our current data, Spirit Airlines ($229), and United Airlines ($541) offers the cheapest pricing from Austin to San Antonio. Spirit Airlines is priced at 59% lower than the current average price of a flight leaving 3 months from now.

  • What does AUS to SAT mean?

    Great question - AUS to SAT just means Austin Bergstrom Airport to San Antonio Airport. Now you’ll know what these unique codes when you look for flights!

  • Can I find deals for flights from Austin to San Antonio that include extra baggage allowance?

    The amount of baggage you can bring on your Austin to San Antonio flight depends on the airline and the type of fare you've chosen. After entering your flight details, you'll be able to view the specific baggage policies for each deal in the search results. Keep in mind that certain deals may offer additional baggage allowance.

  • Can I find deals on flights from Austin to San Antonio with specific airlines?

    Yes, Cheapflights allows you to browse and filter Austin to San Antonio flight deals by airline. After entering your origin and destination, use the available filters to view flights offered by airlines.

  • Can I find deals for flights from Austin to San Antonio that include hotel bookings?

    Yes. In addition to deals on Austin to San Antonio flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Austin to San Antonio?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Austin to San Antonio.

  • Can I find deals for business class flights from Austin to San Antonio?

    Yes. Cheapflights offers flight deals from Austin to San Antonio by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • Can I find deals for flights from Austin to San Antonio that allow pets onboard?

    Many airlines flying from Austin to San Antonio offer the option to travel with pets. After selecting a flight deal, you can find more information about the airline's pet policy on their official website or by contacting the airline directly. Please note that additional fees and restrictions may apply.

  • Can I find deals on last-minute flights from Austin to San Antonio?

    Yes, you can often find last-minute deals on Austin to San Antonio flights on Cheapflights. However, these deals can vary and may not always be available. We recommend checking back frequently or signing up for price alerts for the most up-to-date deals.

  • How recently were the Austin to San Antonio flight deals updated?

    The Austin to San Antonio flight deals you see on this page were last updated on 5/28.

  • When is the best time to book a flight from Austin to San Antonio?

    Currently, September is the cheapest month in which you can book a flight from Austin to San Antonio (average of $291). Flying from Austin to San Antonio in March is currently the most expensive (average of $376). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Austin to San Antonio
See prices for flight routes from nearby airports that may be better suited for you.

Dallas/Fort Worth to Hobby flights
Hobby to Dallas/Fort Worth flights
Dallas/Fort Worth to George Bush Intcntl flights
George Bush Intcntl to Dallas/Fort Worth flights
Love Field to Hobby flights
El Paso to Dallas/Fort Worth flights
Dallas/Fort Worth to San Antonio flights
Dallas/Fort Worth to Austin flights
Hobby to Love Field flights
San Antonio to Dallas/Fort Worth flights
Dallas/Fort Worth to El Paso flights
Austin to Dallas/Fort Worth flights
Hobby to El Paso flights
George Bush Intcntl to El Paso flights
Dallas/Fort Worth to Corpus Christi flights
Dallas/Fort Worth to Brownsville flights
El Paso to Hobby flights
El Paso to George Bush Intcntl flights
Love Field to San Antonio flights
Midland to Hobby flights
Hobby to Austin flights
Midland to George Bush Intcntl flights
Austin to El Paso flights
Hobby to Lubbock flights
San Antonio to Love Field flights
McAllen to Hobby flights
George Bush Intcntl to Austin flights
McAllen to Dallas/Fort Worth flights
George Bush Intcntl to Lubbock flights
Lubbock to Hobby flights
El Paso to San Antonio flights
McAllen to Austin flights
Corpus Christi to Dallas/Fort Worth flights
El Paso to Love Field flights
Dallas/Fort Worth to McAllen flights
Lubbock to George Bush Intcntl flights
McAllen to George Bush Intcntl flights
Dallas/Fort Worth to Harlingen flights
Austin to Hobby flights
Austin to George Bush Intcntl flights
Hobby to McAllen flights
Austin to Amarillo flights
Hobby to San Antonio flights
George Bush Intcntl to McAllen flights
San Antonio to El Paso flights
Hobby to Brownsville flights
George Bush Intcntl to San Antonio flights
Love Field to El Paso flights
El Paso to Austin flights
George Bush Intcntl to Brownsville flights

Top 2 airlines flying from Austin to San Antonio

Discover the top 2 airlines that operate flights from Austin to San Antonio. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,696,634 searches. Data last updated mai 28, 2024.
AirlineCheapestAverageFlexibilityOn-time
United AirlinesCheapest$339Average$444FlexibilityNo cancel feeOn-time69%
Search United Airlines flights
American AirlinesCheapest$475Average$669FlexibilityNo cancel feeOn-time71%
Search American Airlines flights
Boston to West Palm Beach flights
Los Angeles to Washington, D.C. flights
Chicago to Rome flights
San Francisco to Hawaii flights
Dallas to Mumbai flights
Orlando to Key West flights
Los Angeles to Melbourne flights
Chicago to New Delhi flights
Los Angeles to Bangkok flights
Los Angeles to Chicago flights
Los Angeles to Bali flights
Austin to Savannah flights

Search flights from Austin to San Antonio by cabin class

Find flights from Austin to San Antonio, based on your preferred cabin class, be it economy, premium economy, business, or first class.
First Class
Business Class
Prem Econ Class
Economy Class

Weekly flight availability from Austin to San Antonio

Explore weekly flight availability from Austin to San Antonio. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated mai 28, 2024.
Sunday0daily flights
Monday0daily flights
Tuesday0daily flights
Wednesday0daily flights
Thursday0daily flights
Friday0daily flights
Saturday1daily flight

Book a flight to one of these trending destinations

User searches for flights to these destinations increased 20% or more in the past 90 days compared to other destinations
Flights to Laayoune Hassan I
Flights to Virac
Flights to Figari-Sud Corse
Flights to Edremit/Korfez
Flights to Rhinelander Oneida County
Flights to Girona Costa Brava
Flights to Brainerd Crow Wing County
Flights to Parikia Paros
Flights to Cortez Montezuma County
Flights to Miyakojima Hirara
Flights to Zadar
Flights to Trapani Birgi
Flights to Provincetown
Flights to Oran Es Senia
Flights to Constanţa Mihail Kogalniceanu
Flights to Vava'u Lupepau'U
Flights to Urumqi
Flights to Hakodate
Flights to Naxos
Flights to Dalaman
Flights to Hyannis Barnstable
Flights to Devils Lake
Flights to Bastia Poretta
Flights to Karpathos

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travelers can enjoy low prices and a wide availability of flights to their desired destinations.

How does Cheapflights help users find flights from Austin to San Antonio?

When you search for this flight from Austin to San Antonio, Cheapflights searches on 900+ travel sites to save you time finding great flight deals online. Additionally, we offer filter features so you can choose a preferred cabin class or airline, see different price ranges, and much more so you can book the flight for you.

Why should you use Cheapflights to find cheap flight tickets from Austin to San Antonio?

Millions of users choose and trust Cheapflights to book the best flight deals from Austin to San Antonio for free. We help you search and compare prices from hundreds of airlines for the right flight just for you.

Can Cheapflights find flights from Austin to San Antonio with no change fees?

Users can book flights with no change fees policies with our dedicated filters. Book flights from Austin to San Antonio flexibly with Cheapflights today.

Can Cheapflights notify me if prices for flights from Austin to San Antonio become cheaper?

Yes, and it’s super simple to set up. Click the bell icon next to the flight deals above and provide a valid email address to enable Price Alerts. That’s it!

100% Free
Cheapflights is completely free to use, so you can start saving the moment you arrive.
Book with Flexibility
Our users can plan ahead with confidence and find flights with no change fees
Travel Smart
Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.
View all available airlines