Via Istanbul

Ranks above both Gulf options because the LHR–IST–SIN routing avoids the advisory zone on both legs. Istanbul is a natural waypoint east from London — no geometric detour, unlike the HKG backtrack.

• LHR–IST uses standard European routing — no restricted airspace. IST–SIN routes east via Iran/Central Asia, which carries a level-1 advisory but no active routing restriction.
• Turkish Airlines and Singapore Airlines share strong codeshare depth on this pairing, providing 4+ daily frequency options from IST to SIN.
• Journey time is now consistently 13.5 hours — stable since late 2023 after airlines settled into post-Russia routes.
• Istanbul hub sits outside the Middle East advisory zone proper, though its geographic position means regional escalations are worth monitoring.
• If Iranian FIR applies sudden NOTAM restrictions, the IST–SIN leg may need mid-route adjustment — a low-probability but non-zero risk.