Ancillary

Why it matters

In the flight domain, itinerary, leg, segment, carrier and seller identity are distinct. Flattening them too aggressively mixes schedule, fare, agent and booking rules. The search UI can be simple, but the source model needs enough detail for repricing and handoff.

What does it look like in practice?

The same itinerary can be sold by multiple agents with different fare brands, baggage and booking conditions. Segment schedule and seller/offer identity are different concepts.

Implementation questions

• Which legs and segments form the itinerary?
• Are marketing and operating carriers separated?
• Is agent/provider identity retained?
• Is the source reference available for repricing?

Common mistakes

• Modeling an offer as flight number plus price
• Mixing marketing and operating carriers
• Embedding agent identity into itinerary identity

Where does it appear in the travel stack?

Ancillary commonly appears across flight layers. Its implementation should make source-of-truth, identity, freshness and transaction-ownership boundaries explicit.

Related terms