NEW YORK (AP) — JetBlue shares soared Tuesday after the airline gave an April revenue forecast that was much stronger than those from competitors.

The airline said it was getting a boost from its Mint premium service on coast-to-coast flights and from schools in the Northeast spreading spring break over several weeks.

JetBlue said that revenue for every seat flown one mile in April would rise by between 3 percent and 4 percent. That figure is watched closely in the airline business, and it rises when an airline fills more seats or reaps higher average fares.

In the past two weeks, American, United and Delta forecast that revenue per seat would decline anywhere between 2 percent and 6 percent in the second quarter, which runs through June. JetBlue didn't give a full-quarter outlook, but executive vice president Marty St. George said that per-seat revenue in May and early June would be "modestly" higher than a year ago.

In late afternoon trading, shares of New York-based JetBlue Airways Corp. were up $1.39, or 7.1 percent, to $21.10. That represents a 33 percent gain since the start of the year.

JetBlue's Mint service, which features lie-flat seats, was launched last summer on flights between New York and both Los Angeles and San Francisco. Prices start around $599, which undercuts the price of business-class seats on rivals. On a conference call with analysts, executives said that per-seat revenue was up 20 percent from a year ago on routes with Mint seats.

The airline has announced it will expand Mint to New York-Aruba and New York-Barbados in November, and said Tuesday that additional routes were under consideration.

Executives also said that a partnership with Middle Eastern carrier Emirates has boosted traffic.

In the first quarter, JetBlue earned $137 million, or 40 cents per share, compared with $4 million, or a penny per share, a year ago. That was slightly higher than Wall Street expectations. Ten analysts surveyed by Zacks Investment Research gave an average forecast of 39 cents per share.

Revenue rose 13 percent to $1.52 billion, matching the analysts' average forecast.