London Heathrow Airport published a new set of Operational Advice Notices (OANs) late on 14 September, warning airline and ground-handling partners of planned overnight power cuts affecting Terminals 3 and 5. The notices—ASWorks OAN 523 (Terminal 5) and OAN 518 (Terminal 3)—advise that mains electricity will be taken offline for essential maintenance between 23:30 and 04:30 local time on consecutive nights starting 15 September. During the outages, jet-bridges, baggage belts and Fixed Electrical Ground Power units in the affected piers will switch to generator backup. Airlines have been instructed to revise stand allocations, ensure sufficient Unit Load Device (ULD) dollies are positioned ahead of time, and brief flight crews on “APU-on-stand” exemptions where auxiliary power is required. While passenger impact is expected to be limited—work windows largely avoid the day-time peak—long-haul services arriving from Asia-Pacific may face slightly longer ground times. Heathrow says additional Border Force officers will be rostered to process any bunching at immigration control, and Business First security lanes will open 30 minutes early for departing travellers. Corporate mobility teams should advise travellers with tight connections to monitor airline apps for gate changes and allow extra time for Terminal 5 transits, where the inter-terminal transit system will operate on reduced frequency. Air freight shippers using belly-hold capacity are also being asked to lodge time-critical consignments by 18:00 on outage days to guarantee build-up. The OANs come as Heathrow continues a summer-long infrastructure resilience programme following the 8 September air-traffic-control fault that grounded hundreds of flights nationwide.
