From the blog

Schedule data, in the open.

Where airline schedule data is headed, why the industry's tooling is ripe for a reset, and notes from building SSIM Toolkit.

Grouped summer and winter capacity bars across the months of a year, showing the seasonal shape of an airline schedule, in Active Flights brand violet on near-black.
·Scheduling

Summer vs winter: how airlines rebuild the schedule twice a year

Airlines don't run one schedule — they run two, rebuilt every season. Here's why the summer and winter schedules differ, how the seasons are defined, and why 'what changed' is the question that never goes away.

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A pipeline of airline planning stages from network planning through publication to day of operations, in Active Flights brand emerald on near-black.
·Scheduling

The airline planning cycle, end to end

How a flight goes from a line on a network plan to an aircraft at a gate — network planning, scheduling, fleet assignment, slots, publication, and day-of-ops — and where schedule data ties it all together.

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A time-of-day slot strip with allocated and constrained slots beside a Level 3 coordinated-airport badge, in Active Flights brand emerald on near-black.
·Scheduling

Airport slots and the schedule: a plain guide to coordination (WASG basics)

At the world's busiest airports you can't just publish a flight — you need a slot. Here's how slot coordination works, the three airport levels, and why the schedule and the slot book have to agree.

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A validation panel listing schedule issues, some flagged as real errors and some acknowledged as known conventions, in Active Flights brand amber on near-black.
·SSIM

The data-quality edge cases that break schedule parsers

A field guide to the real-world quirks in SSIM feeds — time modes, overnight arrivals, DST, operational suffixes, season edges — that turn a 'simple' fixed-width parser into a maintenance treadmill.

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A connection timeline showing an inbound flight, a connection gap measured against the minimum connect time, and an outbound flight, in Active Flights brand amber on near-black.
·Scheduling

Minimum Connect Time (MCT): the hardest number in scheduling

MCT decides whether a connection is sellable — and it's conditional, per-airport, and lives outside the schedule file. Here's why this one number is so easy to get wrong, and what it takes to get it right.

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Schedule-change action-code chips — NEW, CNL, TIM, EQT — flowing from a schedule to downstream systems, in Active Flights brand blue on near-black.
·SSIM

SSM and ASM: how schedule changes actually travel

A schedule is published once, then changed constantly. SSM and ASM are the IATA messages that carry those changes — bulk and ad-hoc — with action codes like NEW, CNL, TIM and EQT. Here's how they work.

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A stack of five labelled SSIM record-type rows — a header, a carrier record, a flight leg, a segment record, and a trailer — in Active Flights brand blue on near-black.
·SSIM

SSIM Chapter 7 record types, explained: reading a schedule file end to end

A field-level walk through the SSIM record types — header, carrier, flight leg, segment data, and trailer — with a sample file, the fields that matter, and the gotchas that bite parsers.

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One flight represented by a marketing carrier code and a separate operating carrier code, showing the split between who sells and who flies, in Active Flights brand cyan on near-black.
·Scheduling

Codeshares, wet leases, and operating carriers: reading who really flies

The flight number you book isn't always the airline that flies you. Here's the difference between marketing and operating carriers, codeshares, and wet/dry leases — and how it all shows up in the schedule.

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A raw fixed-width SSIM record line decoding into labelled structured fields, in Active Flights brand cyan on near-black.
·SSIM

What is IATA SSIM? A plain-English guide to the format that runs airline schedules

SSIM is how the airline industry exchanges its schedules — a fixed-width, 200-byte text format that's deceptively simple and genuinely hard to get right. Here's what it is and why it matters.

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