At cruise altitude, the geometric horizon is further away — the sun is visible for longer after local ground-level sunset, and becomes visible earlier before ground-level sunrise.

Ground sunrise and sunset are calculated using the NOAA Solar Calculator algorithm — a complete astronomical formula accounting for the equation of time, solar declination, and atmospheric refraction (0.833° correction). No internet required.

• Accurate to ±1–2 minutes globally
• Handles all latitudes including polar regions
• Accounts for atmospheric refraction

Strictly, Fajr (dawn) begins at astronomical dawn — typically 18° below the horizon — not at sunrise. This calculator displays sunrise as an approximation for Fajr, following the our procedure approach. Always cross-reference with an official Islamic prayer time source for religious precision.

Location uses your device's GPS — no internet required. Works at cruising altitude (aircraft GPS receivers operate independently of cellular/Wi-Fi).