About 56% Starlink odds, weighted to recent UA391 flights. A firm answer comes about 2 days before departure, once the aircraft is assigned.
Based on 73 recent flights; Starlink found in 4 of 7 Wi-Fi checks since Apr 16, 2026 (last N77542, Oct 11, 2026).
Aircraft seen on UA391: Boeing 737-800, Boeing 737 MAX 8.