Spirit Airlines stock is rising on better-than-expected results. Image credit: The Motley Fool

Shares of Spirit Airlines (NYSE:SAVE) stock were up 4.2% as of 2:10 p.m. Eastern today, rising on better-than-expected fourth-quarter earnings. Here's a closer look at the final totals versus Wall Street's projections:

Spirit AirlinesRevenueYOY GrowthEPSYOY Growth
Consensus estimate  $475.71 million 7.6%  $0.78  39.3%
Fiscal Q2 actuals  $474.49 million 12.9%  $0.80  42.9%
DIFFERENCE  (1.22 million) 5.3%  $0.02  3.6%

Sources: S&P Capital IQ and Spirit Airlines press release

For the full year, Spirit Airlines reported $1,931.6 million in revenue and $3.23 a share in non-GAAP profit. Analysts tracked by S&P Capital IQ were calling for $1,932.9 million and $3.21 a share, respectively.

"During 2014, we improved our customers' understanding of our Bare Fare plus Frill Control product design, which led to increased customer satisfaction, improved our financial results, and maintained a very high completion rate while improving our on-time performance by 600 basis points," said CEO Ben Baldanza in a press release.

What went right: Spirit's fleet expansion included taking delivery of seven new A320 aircraft during the quarter, leading to an 18.9% increase in available seat miles (ASM) and a 17% increase in revenue passenger miles (RPM). The resulting efficiencies helped push cost per available seat mile (CASM) down 2.9% before accounting for fuel. 

What went wrong: Yet there's more work to do. Load factor dipped 1.4 percentage points as flights departed full just 84.8% of the time versus 86.2% in last year's Q4. Operating revenue per available seat mile also fell 5.1% as passenger ticket prices dipped 6.1%. Spirit remains in the early stages of putting its newest aircraft to work.

What's next: Unfortunately, Spirit Airlines didn't provide guidance in its press release. What can investors look forward to? Analysts tracked by S&P Capital IQ have the low-cost carrier generating $518.3 million in revenue and $0.99 a share in adjusted profits in the first quarter. Both figures would represent meaningful improvement over last year's Q1 results. ($437.99 million and $0.52, respectively). 

Longer term, they have Spirit Airlines generating 24.52% average annual earnings growth during the next three to five years.