Turn your iPhone into an Altimeter Without Ads. Key Features: - Blue Sky with Moving Clouds - Accuracy Display - Current Position on Map - In-App Purchase: 16 Background Colors Please note: Walls, vehicle roofs, tall buildings and other obstructions can block line of sight to GPS satellites. To improve the accuracy, make sure that you maintain a clear view of the horizon in several directions. GPS accuracy varies depending on the number of visible GPS satellites. Locating all visible satellites can take several minutes, with accuracy gradually increasing over time.