Receipts
Everything on the main page is computed from public, verifiable sources. This page is the itemized proof: where each pixel, number and sound comes from, what it cost, and how fast it loads. Measured 2026-08-27.
Live data
| Positions | OpenSky Network — opensky-network.org, registered API (OAuth2). One global state fetch per 30 s cache window, 4 credits each; measured 669 ms authenticated, feed lag ≈ 19 s. ADS-B positions are public radio broadcasts from the aircraft themselves. |
| Filter | DAL callsigns only — Delta mainline. Delta Connection regionals (SkyWest, Endeavor, Republic) are deliberately excluded for brand clarity; that is why flight-tracking apps show roughly twice the number on our board. |
| Routes | adsbdb.com — community callsign→route database; measured p50 200 ms, 100% resolution on a 50-flight live sample, of which ~56% passed our great-circle sanity check. Routes that fail the check are treated as unresolved: a dot without an arc, never a wrong arc. Route-based stats are computed on the tracked subset and labeled as such. |
| Freshness | The updated Xs ago counter is computed against the upstream feed timestamp — CDN cache age included. It cannot understate the data's age. |
| Dawn finale | The accelerated sunrise is the one simulated moment in the piece, and it says so on screen: time ×3600 (6 real hours in 6 seconds). It returns to true time before the board comes back. |
Imagery & type
| Earth (day) | NASA Visible Earth — Blue Marble Next Generation (source), public domain. Processed to 4096×2048 AVIF, 371 KB. |
| Earth (night) | NASA Visible Earth — Black Marble 2016 (source), public domain. 4096×2048 AVIF, 127 KB. The day/night terminator is computed client-side from the clock — it is right now's terminator. |
| Display face | Clash Display — Fontshare, ITF Free Font License ($0 commercial). |
| Data face | JetBrains Mono — SIL Open Font License. |
| Frame face | Switzer (Reasoned Web brand, opening/closing only) — Fontshare FFL. |
Sound
| Split-flap clacks | Synthesized in WebAudio at runtime — band-passed noise transient plus a low mechanical thock, voice-capped so a cascade never becomes a machine gun. No samples, no licenses, fully deterministic code. |
| Narration | Synthetic voice — "Russ", ElevenLabs licensed library, commercial plan. Three moments only — the declaration, the reveal, the close (122 KB total, captions always on, the no-sound path stays complete). Never a clone or imitation of any real person. |
Measured budgets
| Critical path | 233 KB gzipped (HTML 1.6 + CSS 2.4 + JS 127.6 + fonts 101.5) — budget ≤600 KB. TTI on Chrome DevTools "Slow 4G" ≈ 1.5 s. |
| Textures | 498 KB AVIF (both hemispheres of imagery) — streamed behind the context letter. |
| First full load | ≈731 KB — budget ≤4 MB. |
| Rendering | One draw call for all aircraft (instanced sprites), one for all arcs. WebGL only for the globe; the board, letter and chapters are DOM. |
The keynote this evokes
On January 7, 2025, Delta Air Lines opened CES from inside Sphere, Las Vegas — the first CES keynote staged there, for the airline's centennial. Coverage: Delta News Hub · Event Marketer · full keynote video. This piece is an independent study that evokes that event's premise with 100% original content — no Delta footage, logos, slogans, livery or trade dress are used.
Independent concept demonstration. Not affiliated with, sponsored, or endorsed by Delta Air Lines. "Delta" is used descriptively to refer to publicly broadcast flight data. Standing takedown: on any objection, this page comes down the same day. Built by Reasoned Web.