Airlines are considered some of the best employers in the U.S. – in fact, two airlines ranked in the top 50 employers for 2017, beating out companies like Apple Inc. (AAPL), Microsoft Corporation (MSFT​) and even Ikea when it comes to treating their people well. 

Perhaps that's why competition is so fierce for airline jobs. In fact, in 2012, Delta Air Lines, Inc. (DAL) received 22,000 applications for 300 flight attendant openings in the space of one week, which works out to something like two applications per minute and an acceptance rate of about 1.3%. Mathematically speaking, it is four times harder to get a flight attendant job at Delta than it is to get accepted to Harvard, which had a 2016 acceptance rate of 5.4%. (See also: Bizarre Airline Rules You Might Need to Know.)

That being said, for those who are accepted, the perks can be phenomenal – free travel, good pay, generous benefits and in many cases a happy work-life balance. There are 12 major U.S. airlines and a plethora of regional carriers to choose from if you're looking for a new career in the air industry. Are you wondering who has the happiest employees? Here's our list for 2017. (See also: Which Airlines Give Free Meals to Economy Passengers?)

Delta Air Lines, Inc. (DAL)

Delta not only breaks the top 20 in Forbes' list of the 50 best places to work in 2017, it also won Glassdoor's  Employees' Choice Award for the Best Place to Work in 2016. If you love the idea of free travel, Delta has one of the more generous plans in the industry – spouses, children, parents and even friends qualify for free or reduced-price travel to the company's worldwide destinations.

Delta's retirement plan is pretty generous, too, with an automatic 2% contribution and 100% matching on up to 6% of the eligible salary. There's also profit sharing (in 2016, the company distributed over $1 billion in profit sharing). Medical, dental and vision insurance plus a flex spending account and optional disability round out the insurance benefits. Delta currently employs about 80,000 people worldwide. (See also: Delta Employees to Receive 6% Raise.)

Southwest Airlines Co. (LUV)

If job security is your number one concern, you'll love Southwest. In 45 years of operations, the company has never laid off a single employee (there are currently over 53,500 of them). Southwest also ranks on the Forbes Top 50 list and was recognized with a Glassdoor Employees' Choice Award. Most workers cited flexibility and a culture of appreciation as the reasons they loved working at Southwest.

The company has a generous free and reduced-rate travel policy – Southwest offers a Guest Pass program so employees can "share the love" with people not covered by the dependent flight program. In addition, the company matches up to 9.3% of eligible 401(k) contributions and has an employee stock purchase plan. The company website says that health insurance benefits cost as little as $15 per month for medical, dental and vision. (See also: Who Is Driving Southwest Airlines' Management Team?)

JetBlue Airways Corporation (JBLU)

In 2016, JetBlue took the top spot on the Forbes list of top employers in the transportation and logistics category and came in at number eight overall, although it dropped a few places in 2017. Competition is stiff for a job with the nation's favorite economy airline – there are currently just 20,000 employees, and JetBlue's applicant acceptance rate is around 5%.

The company's website is vague when it comes to employee perks, but JetBlue does offer a comprehensive package of insurance, retirement and profit-sharing benefits. In addition to free JetBlue travel, employees receive reduced-rate standby flights on other major airlines. The pay tends to be a bit low in comparison with other carriers, but employees seem to think that the corporate culture and perks are worth the salary trade-off. (See also: JetBlue Offers Free WiFi to All: How Do Other Airlines Compare?)

United Continental Holdings, Inc. (UAL)

There's no denying that United had some serious problems after its merger with Continental in 2010, and customers made their displeasure known. Plus, the company's CEO stepped down amid a Department of Justice investigation around his business dealings. In this context, it's no wonder that employee morale bottomed out. However, new CEO Oscar Munoz prioritized an engaged and happy workforce, and his efforts have paid off.

Today, despite a string of bad press over customer service fails that have left passengers less than impressed with the carrier, United consistently receives high ranks from its employees, who appreciate the company's flexibility, opportunities for growth and advancement, and generous benefits. Plus, pay rates are consistently among the highest in the industry across all occupations. In addition to free travel, a robust retirement plan and profit sharing, employees are eligible for bonuses for customer satisfaction and on-time arrival. The company currently has about 80,000 employees. (See also: United Airlines to Reduce Management Team.)

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