SkySight Wave

SkySight Wave is an iPad app for the pilots of the Perlan Project — the glider that rides mountain waves up into the stratosphere in pursuit of the world altitude record. To climb a wave you first have to find it, and it shifts and changes as you go higher. The app turns SkySight's wave forecast into a map you can read in the cockpit, at whatever altitude you're flying. I built it in Swift, for somewhere with no signal at all.

The wave, level by level

A mountain wave isn't one fixed thing in the sky — it leans and drifts with altitude, so the band of lift sitting over one ridge down low can be well away from there higher up. SkySight forecasts that in layers, and the app let a pilot step through them: choose an altitude, and the map redrew to show where the wave was at that height, set against the glider's own position. The job was to turn a dense forecast into something you could read at a glance and act on, hands full, in the middle of a record attempt.

No signal where it flies

The Perlan flights happen over remote Patagonia, and then tens of thousands of feet above it, where there's no connection to lean on. So everything the app needed had to be aboard before launch. SkySight's charts were pulled down ahead of time and stored on the device, and the Mapbox base map was cached the same way, so the map and every wave layer on it kept working with no network to reach for. Nothing in the app could assume a signal once the canopy was closed.

No second chance

For a flight like that, the app is part of the plan as much as the safety margin — there's no refreshing it, and no calling the ground for a better answer. It had to be right the first time and fully offline, read through a pressure suit near the top of the atmosphere. I fly gliders myself, which made it one I was glad to get right.