Last week, shares of Hawaiian Holdings (NASDAQ:HA) plunged to a 52-week low after the Hawaii-based leisure airline slashed its unit revenue guidance for the fourth quarter. Industry capacity between the West Coast and Hawaii has grown faster than demand this year. Investors are worried that the situation could become even worse in 2019, when Southwest Airlines plans to enter the market.

Hawaiian Holdings' annual investor day, held on Tuesday, represented an opportunity to calm investors' nerves. Clearly, management didn't succeed, as the stock plunged more than 4% to a new multiyear low. Let's take a look at what Hawaiian Airlines revealed about its plans to get back on track in 2019 and beyond.

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Hawaiian Airlines Stock Performance, data by YCharts.

Slower and more profitable growth

Between 2015 and 2017, Hawaiian Airlines increased its capacity at a steady 3% to 4% annual clip. However, capacity growth is set to come in between 5.5% and 6.5% in 2018, as the carrier has added 11 Airbus A321neo jets to its fleet over the course of the year.

This uptick in Hawaiian's growth rate has contributed to its recent unit revenue pressure. But in 2019, Hawaiian Airlines expects to increase its capacity just 1.5% to 4.5% year over year. The majority of that growth will come in new markets -- mainly the new Honolulu-Boston route that will launch in April.

Furthermore, capacity in Hawaiian's main cabin is actually expected to decline 2% to 4% next year. This will be more than offset by 5% to 7% higher capacity in the premium cabin and an 18% to 20% surge in the capacity devoted to "Extra Comfort" seats, which offer more legroom (plus other amenities) and are somewhat pricier than standard coach seats.

An Extra Comfort section on a Hawaiian Airlines plane.

Hawaiian Airlines is adding lots of extra-legroom seats to its fleet. Image source: Hawaiian Airlines.

Hawaiian Airlines has experienced increasing demand for these pricier seats. The replacement of its last few Boeing 767s with Airbus A321neos is allowing the carrier to significantly improve the mix of seats it sells, which should bolster unit revenue in 2019.

Incremental initiatives to boost revenue

Management also highlighted some other actions designed to boost unit revenue growth. Most notably, Hawaiian will introduce a "basic economy" product in the second half of 2019, joining most of its peers. This will make it easier to match other carriers' fares without hurting unit revenue too much.

Hawaiian Airlines also matched its rivals last month by increasing its checked-bag fees on mainland-Hawaii routes. Other recent and ongoing projects that could boost revenue next year include the full rollout of dedicated cargo service between the Hawaiian Islands, modifications to the airline's cobranded credit card program, and the implementation of a planned joint venture with Japan Airlines.

There were no dramatic changes announced during the investor day presentation. But all of these smaller moves together could help Hawaiian Airlines return to unit revenue growth sometime in 2019.

Unit cost increases will slow but not stop

Earlier this year, management projected that Hawaiian Airlines' nonfuel unit costs (excluding special items) would be flat or down in 2019. However, the company now expects nonfuel unit costs to be flat to up in the low single digits next year.

The change in its outlook is partially because nonfuel unit cost growth is on track to come in at the low end of its guidance range for 2018, following a recent forecast update. Additionally, the company's decision to slow its growth rate a little more than previously planned is putting some upward pressure on unit costs.

On the other hand, Hawaiian Airlines expects to offset any nonfuel unit cost pressure with lower fuel burn. (The Airbus A321neos are 25% more fuel efficient than the 767s they are replacing.) Plus, if recent declines in market jet fuel prices hold over the next 12 months, total unit costs (including fuel) will decline on a year-over-year basis in 2019.

A Hawaiian Airlines A321neo parked on a tarmac.

The Airbus A321neo will drive big fuel efficiency gains next year. Image source: Hawaiian Airlines.

Bigger changes could come in 2020 if necessary

Investors' negative reaction to the investor day presentation is understandable. The introduction of a basic economy product was the only noteworthy change announced, and it will have very little impact on Hawaiian Airlines' 2019 results. Meanwhile, nonfuel unit costs are on pace to come in a little higher than management had hinted previously.

However, the carrier still has plenty of levers it can pull to improve performance if competitive pressures intensify next year. Most importantly, the leases for Hawaiian's first three Airbus A330s will expire in 2020. This will give the carrier the flexibility to shrink its capacity if that's what it takes to rebalance supply and demand in the West Coast-Hawaii market.

It looks like 2019 could be a volatile year for Hawaiian Airlines, but the company is starting with a strong balance sheet and profit margins above the industry average. Patient shareholders could be handsomely rewarded if they stick with Hawaiian Holdings over the next few years.