Notes on SSIM, airline schedule data, and the tooling around it.https://activeflights.com/https://activeflights.com/blog/farnborough-2026-preview/https://activeflights.com/blog/farnborough-2026-preview/The Farnborough International Airshow (20–24 July 2026) will book billions in new aircraft orders. Those orders land on a backlog already stretching a decade — which means the real work happens later, in the schedule.Wed, 08 Jul 2026 00:00:00 GMThttps://activeflights.com/blog/iata-mid-2026-demand-dip/https://activeflights.com/blog/iata-mid-2026-demand-dip/In May 2026 global air travel demand actually fell year-on-year — yet load factors hit a record for the month. That apparent contradiction says a lot about how tight, and how regional, the 2026 network has become.Fri, 03 Jul 2026 00:00:00 GMThttps://activeflights.com/blog/aviation-software-spend-2026/https://activeflights.com/blog/aviation-software-spend-2026/Airlines and airports are set to spend around $46B on IT, with AI everywhere. Almost none of it targets the schedule-data layer every operation runs on. For investors, that gap is the interesting part.Thu, 02 Jul 2026 00:00:00 GMThttps://activeflights.com/blog/advanced-air-mobility-scheduling/https://activeflights.com/blog/advanced-air-mobility-scheduling/eVTOL aircraft are moving from concept to the airshow flight line. When electric air taxis start operating at scale, they'll bring a scheduling problem that looks familiar — just faster, denser, and newer.Wed, 01 Jul 2026 00:00:00 GMThttps://activeflights.com/blog/saf-refueleu-fuel-premium/https://activeflights.com/blog/saf-refueleu-fuel-premium/Europe's SAF mandate is ramping, sustainable fuel still costs three to four times conventional jet fuel, and supply sits at a handful of airports. That combination is quietly reshaping network economics — and adding another airport-level dataset to the schedule.Sat, 27 Jun 2026 00:00:00 GMThttps://activeflights.com/blog/investors-map-aviation-schedule-tooling/https://activeflights.com/blog/investors-map-aviation-schedule-tooling/A foundational layer, a durable standard, a recurring need — and almost everyone still building it in-house. Here's the investor's-eye view of schedule-data tooling: the buyers, the wedge, the moats, and the honest risks.Thu, 25 Jun 2026 00:00:00 GMThttps://activeflights.com/blog/modern-airline-retailing-ndc/https://activeflights.com/blog/modern-airline-retailing-ndc/The industry is slowly replacing the PNR/e-ticket/EMD trio with NDC offers and ONE Order. It's a real modernization of how flights are sold — but it doesn't change what everything is sold on top of: the schedule.Fri, 19 Jun 2026 00:00:00 GMThttps://activeflights.com/blog/2026-capacity-squeeze/https://activeflights.com/blog/2026-capacity-squeeze/Airlines are flying at record load factors on a ~3.9% net margin while new aircraft stay scarce. When every seat counts this much, the schedule is where efficiency is won or lost.Tue, 16 Jun 2026 00:00:00 GMThttps://activeflights.com/blog/why-now-2026-forces/https://activeflights.com/blog/why-now-2026-forces/Capacity discipline, a decade-long fleet backlog, a permanent fuel premium, and a slow distribution overhaul are all landing at once. Each, independently, raises the value of getting schedule data right.Fri, 12 Jun 2026 00:00:00 GMThttps://activeflights.com/blog/aircraft-rotations-tail-assignment/https://activeflights.com/blog/aircraft-rotations-tail-assignment/A schedule is a list of flights; an operation is a set of aircraft each flying a connected sequence. Turning one into the other — building rotations and checking they're physically possible — is where the schedule meets reality.Tue, 09 Jun 2026 00:00:00 GMThttps://activeflights.com/blog/schedule-data-platform-economics/https://activeflights.com/blog/schedule-data-platform-economics/Recurring need, near-zero marginal cost, high switching cost, and a position under the whole stack. The unit economics of a foundational schedule-data tool are quietly attractive — here's the shape of them.Fri, 05 Jun 2026 00:00:00 GMThttps://activeflights.com/blog/airline-software-stack/https://activeflights.com/blog/airline-software-stack/Airline technology is a layered stack, from passenger apps at the top to the data that everything runs on at the bottom. Schedule data is that bottom layer — and it's the least-invested-in part of the whole thing.Thu, 28 May 2026 00:00:00 GMThttps://activeflights.com/blog/aircraft-equipment-codes/https://activeflights.com/blog/aircraft-equipment-codes/The 'equipment' field in a schedule is a short code for an aircraft type — and there are two competing code systems for it. Knowing which is which, and mapping between them, is a small skill that prevents big mistakes.Tue, 26 May 2026 00:00:00 GMThttps://activeflights.com/blog/aircraft-backlog-reshaping-schedules/https://activeflights.com/blog/aircraft-backlog-reshaping-schedules/Order books stretch past 16,000 aircraft and deliveries run years late. When the fleet plan can't be trusted, the schedule becomes a moving target — and schedule agility becomes a competitive asset.Thu, 21 May 2026 00:00:00 GMThttps://activeflights.com/blog/data-infrastructure-moat/https://activeflights.com/blog/data-infrastructure-moat/In a foundational data tool, the defensibility isn't the interface — it's the domain encoded into the data layer, the trust that comes from determinism, and the gravity of being the thing everything else is built on.Tue, 19 May 2026 00:00:00 GMThttps://activeflights.com/blog/schedules-to-data-warehouse/https://activeflights.com/blog/schedules-to-data-warehouse/A fixed-width schedule file and an analytics warehouse want very different shapes. Getting from one to the other — typed, normalized, partitioned, columnar — is the unglamorous work that makes schedule data queryable at scale.Tue, 12 May 2026 00:00:00 GMThttps://activeflights.com/blog/ai-outside-determinism-inside-mcp/https://activeflights.com/blog/ai-outside-determinism-inside-mcp/Almost every airline is investing in AI — but you don't want a model guessing your schedule numbers. The right architecture puts a deterministic engine at the core and AI on the outside, via an open standard called MCP.Tue, 05 May 2026 00:00:00 GMThttps://activeflights.com/blog/vertical-saas-aviation/https://activeflights.com/blog/vertical-saas-aviation/Horizontal software is a knife fight. The durable value increasingly sits in vertical SaaS — deep, domain-specific tools for industries with real complexity. Aviation, and its schedule-data layer in particular, is a textbook example.Tue, 05 May 2026 00:00:00 GMThttps://activeflights.com/blog/time-zones-utc-dst-schedules/https://activeflights.com/blog/time-zones-utc-dst-schedules/Almost every serious schedule-data bug is, at bottom, a time bug. Local vs UTC, per-station offsets, and daylight-saving transitions turn a simple 'departure time' into one of the trickiest fields in the file.Tue, 28 Apr 2026 00:00:00 GMThttps://activeflights.com/blog/cost-of-getting-the-schedule-wrong/https://activeflights.com/blog/cost-of-getting-the-schedule-wrong/A schedule error is cheap to fix at the desk and expensive everywhere else. Because the schedule sits at the bottom of the stack, one wrong row propagates upward — into revenue, operations, and every automated system that trusted it.Tue, 21 Apr 2026 00:00:00 GMThttps://activeflights.com/blog/local-first-deterministic-tooling/https://activeflights.com/blog/local-first-deterministic-tooling/Two properties do most of the work in trustworthy schedule tooling: the data stays on your machine, and the same file always produces the same answer. Here's why both matter more than they sound.Tue, 21 Apr 2026 00:00:00 GMThttps://activeflights.com/blog/days-of-operation-period-expansion/https://activeflights.com/blog/days-of-operation-period-expansion/A single SSIM flight-leg line isn't one flight — it's a rule that expands into many. Getting that expansion exactly right, across days-of-operation, frequency, and season edges, is where a lot of quiet bugs live.Tue, 14 Apr 2026 00:00:00 GMThttps://activeflights.com/blog/deconfliction-overlapping-flights/https://activeflights.com/blog/deconfliction-overlapping-flights/A schedule can look perfect and still be impossible — an aircraft in two places at once, a turnaround that can't be made. Deconfliction is finding those conflicts at the desk instead of at the gate.Wed, 08 Apr 2026 00:00:00 GMThttps://activeflights.com/blog/build-vs-buy-ssim-parser/https://activeflights.com/blog/build-vs-buy-ssim-parser/Writing your own schedule parser looks cheap — one engineer, a week, done. The real cost is the maintenance treadmill that follows. Here's the total-cost-of-ownership case, honestly.Tue, 31 Mar 2026 00:00:00 GMThttps://activeflights.com/blog/seasonal-schedules-summer-winter/https://activeflights.com/blog/seasonal-schedules-summer-winter/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.Tue, 17 Mar 2026 00:00:00 GMThttps://activeflights.com/blog/airline-planning-cycle/https://activeflights.com/blog/airline-planning-cycle/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.Tue, 24 Feb 2026 00:00:00 GMThttps://activeflights.com/blog/airport-slots-and-the-schedule/https://activeflights.com/blog/airport-slots-and-the-schedule/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.Tue, 10 Feb 2026 00:00:00 GMThttps://activeflights.com/blog/data-quality-edge-cases/https://activeflights.com/blog/data-quality-edge-cases/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.Wed, 28 Jan 2026 00:00:00 GMThttps://activeflights.com/blog/minimum-connect-time-mct/https://activeflights.com/blog/minimum-connect-time-mct/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.Tue, 13 Jan 2026 00:00:00 GMThttps://activeflights.com/blog/ssm-asm-schedule-messaging/https://activeflights.com/blog/ssm-asm-schedule-messaging/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.Thu, 18 Dec 2025 00:00:00 GMThttps://activeflights.com/blog/ssim-record-types-explained/https://activeflights.com/blog/ssim-record-types-explained/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.Wed, 03 Dec 2025 00:00:00 GMThttps://activeflights.com/blog/codeshares-wet-leases-operating-carriers/https://activeflights.com/blog/codeshares-wet-leases-operating-carriers/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.Wed, 26 Nov 2025 00:00:00 GMThttps://activeflights.com/blog/what-is-iata-ssim/https://activeflights.com/blog/what-is-iata-ssim/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.Wed, 12 Nov 2025 00:00:00 GMT