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 at every stage, 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. Optional Pro features add workflow tools and modelling refinements without changing the underlying calculation engine. Why This App? Accurate 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. Flight Day/Night Calculator makes the process transparent and repeatable. Calculations and airport lookup work offline 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, showing the route, aircraft position, day/night shading, and civil twilight throughout the flight. Free users can explore take-off, midpoint, landing, and civil twilight transitions. Pro unlocks the full timeline, allowing you to scrub through the flight or play it back over the globe. Route Globe visualises the same calculation and does not alter the underlying day/night results. 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. The app does not use automatic timezone or DST detection. Nautical twilight, astronomical twilight, and altitude-adjusted sunrise/sunset are available in Pro. Regulatory 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 at key points and civil twilight transitions * Offline airport search and lookup * Custom coordinate entry * Block time (OOOI) and airborne calculations * Distance and average groundspeed * Estimated Uncertainty * High-latitude cautions * Input validation * Full results display Pro adds: * Full Route Globe timeline and playback * Up to 20 waypoints * Waypoint ATA timing refinement * Local Time Entry using manual UTC offsets * Altitude-adjusted sunrise and sunset * Nautical and astronomical twilight * History access * Text and CSV export * Logbook notes options * Advanced twilight display controls Key Features * UTC-based calculations, results, and exports * Interactive 3D Route Globe * Offline airport database * Search by ICAO, IATA, local identifier, or name * Custom departure, arrival, and location coordinates * Detailed transition events with times and coordinates * Results in hours:minutes and decimal hours * Estimated Uncertainty for twilight sensitivity * Validation for implausible route and waypoint timing * Designed for iPhone and iPad, including Split View * Light and Dark Mode support Privacy & Offline Use Calculations, airport lookup, route processing, astronomy, results, and exports are performed on device. No account is required and the app does not collect personal data. Purchases, subscriptions, restores, and entitlement verification are handled through 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/