Allegiant Travel (NASDAQ:ALGT) had a rough September, as a maintenance issue related to many of its evacuation slides led to widespread delays and flight cancellations. Allegiant had to issue about $1 million in refunds to customers while also incurring additional costs to lease planes from other airlines to get passengers to their destinations.

Yet despite all those handicaps, Allegiant managed to post a record profit last quarter. This strong result is yet another reminder that Allegiant is perhaps the most consistent airline in the industry in terms of financial performance. Shareholders have reaped big gains from that success over the last 10 years, and there is plenty of room for growth going forward.

Another good quarter
Allegiant grew EPS from $0.87 to $0.91 in Q3 despite the financial impact of its slide maintenance problem and investments the company is making to support future growth. A 5.8% year-over-year increase in fuel efficiency was the main driver of Allegiant's financial improvement.

EPS also grew faster than net income because of the company's share repurchase program, and the company bought back another 491,000 shares during the quarter. In fact, Allegiant has the most aggressive policy of returning cash to shareholders of any airline. Allegiant's strong balance sheet makes this possible -- the company has significantly more cash than debt.

Let the good times roll
While Allegiant already has a very lean cost structure that is rivaled only by Spirit Airlines (NASDAQ:SAVE), it continues to work to push costs down further. Allegiant introduced its first Airbus A320-series jets earlier this year, and the company expects Airbus jets to make up a quarter of its fleet by the end of 2015.

These Airbus aircraft are at least 15% more fuel-efficient than the MD-80s that are the backbone of Allegiant's current fleet. They will also be significantly more reliable and will require less maintenance work because they are younger. Lastly, the Airbus aircraft will be able to serve some routes that are not feasible with MD-80s.

Expansion continues
One of the best things about Allegiant for investors is the company's solid long-term growth profile. Allegiant is adding 12 new cities to its route map over the next two quarters, and has 29 new routes scheduled to begin in the fourth quarter alone.

International service is one long-term opportunity that Allegiant's management has been pursuing recently. Allegiant is currently making the necessary technology improvements to support international service and working through the regulatory issues. However, Allegiant President Andrew Levy is very confident that the company will start service to Mexico by the end of 2014.

This will open a host of new route opportunities for Allegiant that fit right into its business model. The company plans to fly from smaller cities in Mexico to U.S. leisure destinations like Las Vegas, while also flying from smaller U.S. cities to Mexican resort areas.

Foolish bottom line
Allegiant's strategy of constantly pushing down costs and focusing on underserved markets has made it the most consistent airline in the U.S. in terms of profitability. Its ability to earn a record profit in spite of last month's evacuation slide snafu showcased that strength. Moreover, the company's current growth initiatives give shareholders a lot to look forward to in the years to come.

Fool contributor Adam Levine-Weinberg has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.