How Flying Works

Why Bags Go Missing on Connecting Flights

On 27 March 2008, London Heathrow opened Terminal 5, built for British Airways and billed as one of the most advanced terminals in the world. Within hours its baggage system was in trouble. BA cancelled dozens of flights that first day and well over 200 in the days that followed, while tens of thousands of bags piled up. Some were sent to a courier firm in Milan, Italy, to be sorted and sent on to their owners. Bosses later put much of the chaos down to IT problems.

Heathrow T5 is an extreme case. But it shows something true of every airport: a checked bag only reaches you if a long chain of machines, messages and people all work. And the weakest link in that chain is the connection.

Your bag has a licence plate

At check-in the agent prints a strip that wraps around the handle. The big three letters are the airport code of your final destination. The part the machines care about is the 10-digit number under the barcode, often called the bag’s licence plate. The first digit is a type code, the next three identify the airline that issued the tag, and the last six are a serial number.

At the same moment, the airline’s system sends a message to the airport’s baggage system linking that number to your flights. From then on, every scanner that reads the barcode looks up the message to decide where the bag goes next.

Interactive · a checked bag’s connection

Tap a stage. Amber diamonds are IATA’s four mandatory tracking points.

What happens · Transfer at the hub

Unloaded at the hub, the bag has to cross the airport to the connecting flight. It may be screened again and sorted a second time.

What goes wrong

The tightest step. Late inbound flight, long distance between gates, or the transfer message arriving late.

Why the transfer is the weak point

On a connection you walk from one gate to another. Your bag has a longer trip. It’s unloaded from the first aircraft, driven or conveyed across the airport, often screened again, sorted a second time and loaded onto the next flight. It has to do all that in the same connection time you have, and it can’t run.

Plenty can slow it down. The first flight lands late and eats the margin. The two gates are at opposite ends of a big hub. The scanner can’t read a crumpled tag, so the bag drops out to be sorted by hand. The connecting flight closes its hold early to leave on time.

The numbers back this up. SITA, which runs IT systems for much of the industry, publishes an annual baggage report. Its 2025 edition counted 6.3 mishandled bags per 1,000 passengers in 2024, with transfers responsible for 41% of them, the biggest single cause. In its 2026 report the overall rate had dropped by 23%, and transfers were down to 39%. Still the top cause.

Baggage conveyor belt in the arrivals hall at Zurich Airport — The baggage claim belt at Zurich Airport, the last of many conveyors a checked bag rides on its journey. Photo: Wikimedia Commons (author and licence on the file page).

Tracking every bag, at four points

Since 1 June 2018, the airline association IATA has asked its member airlines to track each bag at four points under Resolution 753: when the passenger hands it over, when it’s loaded onto the aircraft, when it’s delivered to the transfer area, and when it’s returned to the passenger. The airlines involved in a journey have to share that tracking data. The idea is simple: if you know where a bag was last scanned, you know where to look, and you can often spot a missed connection before the passenger lands.

That data is also why airlines can sometimes tell you a bag will be on the next flight before you even reach the carousel.

What you can do

Leave a longer connection when you can, especially at big hubs and when the first flight is often late.
Check the tag at the desk. The big three-letter code should be your final destination.
Peel off old tags and stickers. An old barcode can confuse the scanners.
Keep essentials in your cabin bag: medicine, valuables, chargers and one change of clothes.
Photograph your bag and the tag receipt. It makes a missing-bag report faster.
Report it before you leave the arrivals hall if it doesn’t appear, and keep the reference number.

Self-service bag drop machines with conveyor belts at Bergen Airport — Self-service bag drop at Bergen Airport, Norway. The tag you print here is the bag’s identity for the whole journey. Photo: Wikimedia Commons (author and licence on the file page).

Sources & Further Reading

Common Questions

Frequently Asked Questions

Why do bags get lost on connecting flights?

Because the bag has more work to do than you. It has to be unloaded, carried across the airport, often screened and sorted again, and loaded onto the next flight, all within your connection time. If the first flight is late or the transfer is tight, the bag can miss the connection. SITA’s industry figures put transfers at around 40% of all mishandled bags.

What do the numbers on my bag tag mean?

The 10-digit number is the bag’s “licence plate”. The first digit is a type code, the next three identify the airline that issued the tag, and the last six are a serial number. The big three-letter code is the airport code of your final destination, not the next stop.

Will my bag go through to my final destination automatically?

Usually, if both flights are on one booking and the airlines have a baggage agreement. Check the tag at the desk: the big airport code should be your final destination. On separate bookings, or when entering some countries, you may need to collect it and check it in again.

How common is it for an airline to mishandle a bag?

Not very. SITA’s 2025 report counted 6.3 mishandled bags per 1,000 passengers in 2024, and its 2026 report says the rate fell by 23% in 2025. Most mishandled bags are delayed rather than lost for good, and turn up on a later flight.

Do luggage trackers like AirTags help?

They don’t stop a bag going astray, but they tell you where it is, which can speed things up when you report it. The airline’s own tracking is the system that actually moves the bag.

← Back to How Flying Works

Last reviewed: October 2026. Facts that change, such as fleets, airspace and airline ownership, are re-checked on a schedule. Spotted an error? Email contact@skyplus.news and we’ll fix it. See how we check facts.