Investors have punished airline stocks recently, as nearly every major U.S. airline has projected a mid-single-digit decline in passenger unit revenue, or PRASM, for Q2. To some extent, this unit revenue pressure is a natural result of the big drop in oil prices over the past year.

However, investors are also blaming airlines for growing supply faster than demand -- with Southwest Airlines (NYSE:LUV) being the primary target of investors' ire. Southwest has said it plans to increase capacity 7% year over year in 2015, but while it held unit revenue flat year over year in Q1, it expects a 4%-5% decline in Q2 PRASM.

Faster growth seems to be hurting Southwest's unit revenue.

But surprisingly to some, rival carrier JetBlue Airways (NASDAQ:JBLU) has had no unit revenue troubles whatsoever -- despite growing just as quickly as Southwest. JetBlue expects capacity to rise 5.5%-7.5% in Q2 and 7%-9% for the full year, but PRASM is still on pace to rise 0.5%-1.5% in Q2, after jumping 4.5% in Q1. Better still, JetBlue's management sees plenty of opportunities to keep growing steadily without sacrificing profitability.

Marty St. George, JetBlue Executive Vice President-Commercial & Planning. Source: JetBlue

Growth opportunities all around
This week, I had the opportunity to spend a couple of hours with JetBlue's EVP of Commercial and Planning, Marty St. George. It was clear that St. George sees immense potential for JetBlue to grow in its existing six focus cities (New York, Boston, Fort Lauderdale, Orlando, San Juan, and Long Beach). And JetBlue can do it while keeping its profit margin steady or growing.

JetBlue's biggest near-term growth opportunity is in Florida, where it is increasingly mounting a direct challenge to Southwest Airlines.

In recent months, JetBlue has announced new flights from its Fort Lauderdale base to Philadelphia, Baltimore, Albany, Mexico City, and Quito starting in late 2015 or early 2016. It also recently inaugurated flights to Cleveland and Detroit. From Orlando, JetBlue also plans to start flying to Baltimore, Albany, and Mexico City later this year.

JetBlue is already close to reaching its goal of growing its Fort Lauderdale operation to 100 daily departures by 2017. However, St. George indicated that there are plenty of additional domestic and international growth opportunities in Fort Lauderdale, mainly due to the strength of demand from customers within South Florida.

He also sees plenty of opportunities in Orlando, as well as Boston. JetBlue has been growing steadily in both of those markets and has the infrastructure in place to continue expanding. But lately, its push to expand in Fort Lauderdale has meant slower growth elsewhere.

Longer-term growth possibilities
In addition to its near-term growth opportunities in Florida (and to a lesser extent, Boston), JetBlue is also working to pave the way for longer-term growth. In New York, still its largest market, JetBlue is still looking to add slots if possible, according to St. George.

In the meantime, St. George is excited by the arrival of JetBlue's new A321s, which have 190 seats -- compared to 150 seats on the A320s that are the mainstay of its fleet.

The interior of a brand new JetBlue A321. Source: Author.

JetBlue has frequent flights from JFK on some routes to Florida and the Caribbean. On those routes, it could potentially offer the same number of seats with one or two fewer flights per day by switching from the A320 to the A321. This would free up slots for new growth opportunities.

JetBlue also faces slot constraints in Long Beach. But whereas in New York the slot constraints are driven by airport capacity, in Long Beach there are artificial limits imposed due to quality-of-life concerns from nearby residents. If these restrictions are eased, JetBlue could resume its growth in Long Beach.

Even without the availability of more slots in Long Beach, JetBlue is pushing for the airport to add a U.S. customs facility to support international flights. St. George told me that the biggest area of interest is the VFR (visiting friends and relatives) market. The large Mexican-origin population in Southern California could support a significant number of flights from Long Beach to Mexico.

Looking even further down the road, JetBlue is evaluating the capabilities of Airbus' recently announced A321LR. As I have previously noted, this model is from the same family as the A320s and A321s that make up the majority of JetBlue's fleet, but would have additional range. This would enable JetBlue to fly from Fort Lauderdale to Brazil or even from Boston to Western Europe -- routes that are out of reach for its planes today.

Plenty of exciting opportunities ahead
In the airline industry, growth is often seen as impeding profitability, at least in the short term. At Southwest Airlines, that story is playing out to some extent, as unit revenue has started to deteriorate due to the carrier's stepped-up growth rate.

But at JetBlue, the opposite is happening. CEO Robin Hayes noted on JetBlue's most recent earnings call that faster-growing markets like Fort Lauderdale and Boston are also posting better-than-average margin expansion: a point that St. George made sure to reiterate to me.

That's very impressive. As long as that continues to be true, JetBlue doesn't have to "ration" its growth in order to minimize the losses from starting new routes. Given JetBlue's plans to add dozens of new planes to its fleet in the next five years alone, shareholders should be thrilled to know that it has abundant options to deploy that new capacity while maintaining or improving its profit margin.