For a second straight year, Delta’s operating profit margin has fallen year-over-year in the first quarter. The reason for the decline, once again, is rising costs. The good news: Rising revenues—from nearly every corner of Delta’s network—propelled the airline to a solid 8% operating profit margin. One of the rising costs is, of course, fuel.

Are fuel prices putting a damper on earnings overall? IAG seems interested in expanding its empire, having purchased a small stake in Norwegian and considering a full takeover. Lion Air, meanwhile, is purchasing planes… lots and lots of planes. In the U.S., Allegiant came under fire over safety concerns. Lastly, Frontier is adding 69 routes this month alone.