The airport is outside the zone, but the route may not be
Heathrow, Gatwick, Stansted, Luton, London City and Southend airports all sit outside the mapped Congestion Charge zone. That does not automatically make an airport journey charge-free. A pickup at a hotel near Westminster, a stop inside the zone or a diversion through central London can still trigger the charge. Check the full route in TfL's official map before travel, then check it again if a closure changes the plan.