Flight Day/Night Calculator

Flight Day/Night Calculator is an offline UTC-based tool for calculating day and night flight time. Built by an airline pilot for pilots, from first night cross-country to long-range operations at high latitudes, it produces clear, repeatable results for logbook use. The core A-to-B calculation engine is fully available in the free tier. Pro adds workflow tools and modelling refinements without changing the underlying calculation engine. Why This App? Day/night splits are difficult to calculate precisely because the sun’s position changes continuously along a route, with boundaries shifting by latitude, season, routing, and timing. The app makes this transparent and repeatable using an on-device airport database and embedded astronomy algorithms. No guesswork. No manual plotting. No sign-in. No data collection. Route Globe Route Globe provides an interactive 3D visualisation of your calculated flight, including route, aircraft position, day/night shading, and civil twilight. Free users can explore key snapshots and twilight transitions. Pro unlocks the full timeline for scrubbing and playback. Flight Track Import Pro users can import recorded flight tracks from supported CSV, TSV, timestamped GPX, and timestamped KML files. Files are analysed on device. The app proposes departure and arrival, estimates relevant flight times where possible, and reduces dense tracks to up to 20 representative waypoints with UTC timing. You review the proposed flight before applying it. Imported values remain editable, and calculation begins only when you tap Calculate. Import supports a single A-to-B flight. Return-to-origin flights, circuits, multiple flights in one file, or unusually complex tracks may not be representable. Imported times are best-effort estimates unless provided by the source. Flight Day/Night Calculator CSV exports can also be re-imported later, independently of in-app History. No tracker account, API connection, or upload is required. How It Works The app computes aircraft position minute by minute using your departure, destination, and optional Pro waypoints. At each point it determines sun elevation and classifies day and night using the standard civil twilight definition: sun at or above −6°. Results are UTC-authoritative. Pro users can optionally enter times using manually selected UTC offsets. No automatic timezone or DST detection is used. Nautical twilight, astronomical twilight, and altitude-adjusted sunrise/sunset are available in Pro. Day/night totals remain based on civil twilight. Free includes: * Direct A-to-B day/night calculation * Minute-by-minute civil twilight classification * Great-circle routing * Route Globe snapshots * Offline airport search and lookup * Custom coordinates * OOOI and airborne calculations * Distance and average groundspeed * Estimated Uncertainty * High-latitude cautions * Full results display Pro adds: * Flight Track Import * Full Route Globe timeline and playback * Up to 20 waypoints * Waypoint ATA refinement * Local Time Entry with manual UTC offsets * Altitude-adjusted sunrise and sunset * Nautical and astronomical twilight * History * Text and CSV export with CSV re-import * Logbook notes options * Advanced twilight controls Privacy & Offline Use Calculations, airport lookup, flight-track analysis, route processing, astronomy, results, and exports are performed on device. Imported files are selected by you and processed locally. Purchases, subscriptions, restores, and entitlement verification use Apple StoreKit. Subscription & Purchase Information Pro is available as Monthly, Annual, or Lifetime access. Pricing is shown in-app and may vary by region. Subscriptions renew automatically unless cancelled at least 24 hours before the end of the current period. Manage or cancel subscriptions in App Store settings. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/