Owing to her Raising Sand collaboration with Robert Plant becoming something of a cultural phenomenon, that Alison Krauss and her superb Union Station band haven’t released a new album together in seven years seems, well, impossible. But them’s the facts. So let it be said that on Paper Airplane, all parties acquit themselves spectacularly well in their reunion moment. On the one hand, the album is standard AK+US fare: the singer’s dulcet voice is as eerie and haunting as ever, and her fiddling above reproach; Jerry Douglas (dobro), Barry Bales (bass), Ron Block (banjo), and Dan Tyminski (guitar, vocals) assert their primacy among roots bands with frequent dazzling displays of virtuosity and good taste in serving the songs and the singer. And what songs! Robert Lee Castleman, a Krauss favorite, contributes the title track, a dense, swirling cry of abject loneliness with a piercing Douglas dobro solo. From Richard Thompson comes “Dimming of the Day,” a doom- laden heartbreaker with Celtic overtones; and from Peter Rowan, the evocative “Dustbowl Children,” which allows Tyminski’s rough-hewn vocal to stand in for those forlorn, wandering Okies. Sparkling production—clean, robust instruments, the voices immaculately framed—caps a bona fide Krauss classic.