Pivotal altitude, in one slide.
PivotalAltitude Pro is a one-screen iPhone app for eights on pylons. Slide to your groundspeed and read the altitude to fly, or let the phone's GPS fill it in.
Coming soon to the App Store for iPhone. A one-time purchase: no subscription, no account.
Try it
The same math the app uses: groundspeed squared, divided by 11.3.
880 ft above the ground
10 kt slower: 720 ft · 10 kt faster: 1,070 ft
What the app does
A groundspeed slider
Slide to your groundspeed in knots or mph and the pivotal altitude updates as you move it.
Fill it in live
Tap "Use GPS groundspeed" and the slider follows the phone's GPS, so the number changes as your groundspeed does.
Feet MSL, too
Add the ground elevation at the pylons, by hand or from GPS on the ground, and see what to hold on the altimeter.
The pitch rule
Pylon moves ahead of the wingtip: push forward and descend. Pylon moves behind: pull back and climb.
Why groundspeed is all it needs
Pivotal altitude is the height at which your line of sight along the wing stays fixed on the pylon through the turn. It depends on how fast you are moving over the ground and nothing else: not bank angle, not weight. Flying downwind your groundspeed is higher, so the pivotal altitude is higher and you climb; turning back into the wind it drops and you descend.
Privacy. The app collects nothing and makes no network requests. If you use the GPS button, your location is read on your phone and never leaves it. See the Privacy Policy.