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The atmosphere has no hard boundary — it grows progressively thinner as altitude increases. At 33,000 feet the bulk of all weather systems lie well below you. At 51,000 feet — the cruise altitude of the Gulfstream G700 — the air surrounding the jet exerts less than a quarter of the pressure found at sea level.
What the eye perceives: the sky shifts from light blue to deep navy, approaching black. Stars become visible in daylight under clear conditions. Passengers aboard commercial airliners who have only ever seen a pale blue horizon will notice the difference immediately. Above FL400 the dark cap above the pale atmospheric haze becomes clearly defined.
Altitude Comparison
Three models routinely reach altitudes that are entirely out of reach for commercial airliners.
Deep dives into altitude, physics and the on-board experience.
Aviation & Space
Elon Musk (SpaceX), Jeff Bezos (Blue Origin) and Richard Branson (Virgin Galactic) share one thing: they have opened the door to space — and they all travel on private jets. Bezos flew above the Karman Line in 2021 aboard New Shepard. Branson reached 53 miles on VSS Unity nine days earlier. Meanwhile, Musk regularly flies a Gulfstream G650ER — the very same aircraft that cruises at FL510.
Explore Billionaire JetsThe Gulfstream G700 reaches FL516 — 51,700 feet or 15,727 meters. That is the highest certified cruise altitude of any civilian aircraft in regular service. By comparison, commercial airliners typically operate between FL330 and FL380.
The Karman Line — the internationally recognized boundary of outer space — sits at 100 km (328,000 ft). The G700 at FL516 is at 15.7 km (51,700 ft): roughly 84 km below. Yet it already sits above 99 percent of all atmospheric mass.
From about 35,000 feet the curvature is perceivable under ideal conditions — provided you have a wide field of view and clear horizon visibility. At FL500 and above the effect is noticeably more pronounced. The sky also darkens to deep navy rather than the pale blue seen from airliner altitudes.
The top three: Gulfstream G700 (FL516, 51,700 ft), Bombardier Global 8000 (FL510, 51,000 ft) and Dassault Falcon 8X (FL510, 51,000 ft). All three fly well above the maximum cruise altitude of any commercial airliner.
Gulfstream G700 at FL516 — free quote, response within 15 minutes.
