About 37% Starlink odds, weighted to recent UA1421 flights. A firm answer comes about 2 days before departure, once the aircraft is assigned.
Based on 132 recent flights; Starlink found in 8 of 13 Wi-Fi checks since Feb 11, 2026 (last N37513, Oct 14, 2026).
Aircraft seen on UA1421: Boeing 737 MAX 9, Boeing 737-900ER, Airbus A321neo, Boeing 737-800.