Claustrophobic and rank, suffused with a clinical fluorescence that does nobody’s mirror reflection any favors: Few places rival the airplane bathroom for inhospitality. Most of us minimize our time there, or avoid it altogether; not so Nina Katchadourian, who has been lingering in skyborne commodes for the past two years—annexing them, along with tray tables, as makeshift studios, and calling herself and fellow passengers into service as models. “Seat Assignment,” 2010–, selections from which comprised her fifth solo show at Catharine Clark Gallery, includes hundreds of photographs, digital