Flight Day/Night Calculator

Flight Day/Night Calculator is a precision offline tool for calculating exact day and night flight time. Built by an airline pilot for pilots at every stage, from first night cross-country to complex long-range operations at high latitudes, it delivers the accuracy and confidence your logbook demands. Why This App? Aviation authorities require accurate day and night flight time splits, but calculating them precisely is genuinely difficult without specialised tools. The sun’s position changes continuously along your route, and day/night boundaries shift with latitude, season, altitude, and groundspeed. Most pilots rely on rough estimates or extrapolate from departure and arrival sun events. Many logbook apps do the same, which leads to significant inaccuracies on longer flights or operations near the poles. Flight Day/Night Calculator makes professional-grade accuracy simple. It performs minute-by-minute position tracking with embedded astronomy algorithms, working completely offline. No guesswork. No manual plotting. Just accurate results you can log with confidence. How It Works The app computes your aircraft’s position every minute using your departure, destination, and optional waypoints (up to 20). At each point it determines the sun’s elevation angle to classify day and night using internationally recognised civil twilight definitions. You can optionally display nautical and astronomical twilight phases, and calculate sunrise and sunset at sea level or corrected for cruise altitude, without affecting regulatory day/night totals. The History view stores the export text for your most recent flights, allowing quick reference to previously calculated results exactly as generated. Location Lookup Search any airport or position and instantly view sunrise, sunset, morning civil twilight (MCT), evening civil twilight (ECT), and complete twilight information for any date. Location Lookup also supports Custom Location entries for ad-hoc positions; these are lookup-only and do not replace airports in the main calculator. This makes it ideal for planning reference and sun-event comparison, allowing pilots to validate expected conditions at both ends of a route, fully offline. Key Features - Direct ICAO entry with airport name confirmation, or full offline airport search - Location Lookup with sunrise, sunset, MCT, ECT, and complete twilight information for any date - Optional waypoints (up to 20) for realistic routing, or fast great-circle mode - Block time (OOOI) or airborne-only calculations with accurate taxi handling - Optional local time entry with manual UTC offset selection for predictable, DST-safe inputs - Accurate worldwide day and night calculation using civil twilight definitions - Optional nautical and astronomical twilight display - Altitude-adjusted sunrise and sunset for cruise flight levels - Customisable logbook notes included in exports - History of recent flights, storing export text exactly as generated - Results in both hours:minutes and decimal hours - Detailed transition events with exact times and coordinates - Distance and average groundspeed always displayed - Input validation to prevent unrealistic or impossible entries - Fully offline with no sign-in, no data collection, and no network requirements - Optimised for iPhone and iPad with a clean pilot-focused design - Full support for Light and Dark mode Designed to Complement Your Logbook Flight Day/Night Calculator works alongside your existing logbook or logbook app, providing reliable day and night splits you can trust. Whether you are building hours toward commercial ratings, maintaining night currency, or logging long-range international flights, this app helps you maintain the level of accuracy your logbook deserves.