Connecting at Heathrow: one booking and separate tickets are different journeys
A terminal number tells you where to go. The way your flights were booked tells you which route through the airport you need.
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On a normal through connection, follow Flight Connections. Heathrow directs separate-ticket passengers through arrivals, baggage collection and a new check-in process.
01Identify the kind of connection before counting minutes
Two flights on the same calendar day can involve very different airport processes. With a normal single-booking connection, Heathrow directs you towards the purple Flight Connections signs. With separate tickets, its guidance is to enter through arrivals, collect checked baggage and check in again. The first question is therefore how the journey is booked, not whether both flights use the same terminal.
Read the booking confirmation and baggage information. A shared airline alliance, a similar flight number or one travel-agency email does not by itself explain how the transfer will work. If the documents are unclear, ask the booking provider to confirm the connection and baggage arrangements before treating the flights as one journey.
02For a through connection, follow the airport’s transfer route
Read the diagram as text
- Arrival
- Taxi, disembark and walk
- Transfer
- Connection bus / walk + security
- Departure
- Reach the gate before boarding closes
Heathrow provides a flight-specific connection planner and free airside transfer buses between terminals. Use the arrival and departure flight details, then follow the Flight Connections route. This keeps you focused on the process for connecting passengers rather than a public transport route intended for people outside the airport.
Connecting passengers pass through security. A connection to a UK domestic flight also involves immigration. These steps take part of the available interval, along with leaving the aircraft, walking and reaching the gate before it closes. The number printed between flight times is not all usable transfer time.
| Stage | What to allow for |
|---|---|
| Arrival | Taxiing, disembarkation and the walk into the terminal |
| Transfer | Terminal bus or walking route, plus security |
| Departure | Boarding and gate-closing time before scheduled take-off |
| Separate tickets | Arrivals, baggage reclaim, landside transfer and new check-in as well |
03With separate tickets, start from the second airline’s deadline
The useful planning method is to work backwards. Find when the second airline closes check-in and bag drop, then allow time to reach that point after the first flight arrives. Add the arrival process and any terminal transfer. Only then can you judge whether the gap looks sensible for your circumstances.
This is particularly important with checked bags: arriving at the airport before the flight departs is not the same as reaching bag drop before it closes. A short connection that works inside the transfer system may be a poor fit for two separate tickets. We would not use a single “90 minutes is enough” rule for both.
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04Sometimes the better connection is an overnight stay
Read the diagram as text
- Through ticket
- Compare the complete protected itinerary
- Separate tickets
- Add baggage, entry and new check-in
- Overnight alternative
- Include room and transport costs
If the cheaper separate-ticket option leaves little room for a delayed arrival, compare it with a through ticket or a longer stop. Include hotel and transport costs where relevant. A fare saving can disappear once you account for the journey you would actually be comfortable making.
Keep the immigration decision separate from the timing calculation. If your plan involves entering the UK, confirm the entry requirements for your own documents before relying on it. For the airport process itself, use Heathrow’s planner with the exact flights; it is more useful than a terminal-to-terminal estimate copied from a different itinerary.
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