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Pro Altimeter - Barometric+GPS
Pro Altimeter - Barometric+GPS Vs. Pilot: Aviation Altimeter

Pro Altimeter - Barometric+GPS vs Pilot: Aviation Altimeter Usage & Stats

Pro Altimeter uses the high-fidelity barometric pressure sensor in iOS devices to measure and compute altitude. Pro Altimeter has a dead simple interface. Barometric altitude and GPS altitude are displayed in large easy to read numbers, showing units of both feet and meters, and giving realtime accuracy estimates from the hardware. At bottom are calibration and display mode buttons. The display offers a highly-readable daytime mode with black digits on an LCD-green background, and a reversed night mode that is easy on the eyes in dark conditions. That's it! Proper calibration is necessary to measure altitude from barometric pressure (this is why a pilot "dials in" the cockpit altimeter before taking off). Pro Altimeter offers four different methods for calibration -- choose the easiest and most convenient: 1. Use GPS altitude. This method correlates the measured local barometric pressure with the altitude measured by GPS. This method can be used when your device has a clear line of sight to the sky and a reliable GPS fix with good accuracy. 2. Manually enter altitude. This method correlates the measured local barometric pressure with known altitude from landmarks, elevation benchmarks, trail markers, topo maps, land surveys, etc. Altitude can be entered in feet or meters. 3. Manually enter pressure. If you have a weather station, weather report, or METAR report with equivalent sea level pressure for a nearby location, this can be used to correlate local barometric pressure to altitude. Pressure can be entered with units of inches Hg, kPa, or mb. 4. Check local airports. With the tap of a button, Pro Altimeter will locate the five closest airports within 100 miles (160km) of your present location anywhere in the world, and pull in METAR data. From that list of five, pick the airport of your choice and Pro Altimeter will import pressure data for calibration. Once calibrated, Pro Altimeter keeps track of the time since its last calibration. Because weather and local barometric pressure change over time, the app will warn you when 6 hours have elapsed since the last calibration by flashing the "CALIBRATE" button. You should calibrate as frequently as practical -- for example, on a hike, calibrate whenever you pass a trail marker or elevation benchmark. But at a minimum, calibrate at least every 6 hours or whenever weather changes in your area. Pro Altimeter is intended for iOS devices with a built-in barometric pressure sensor (iPhone 6 and later, iPad Air 2 and later, iPad mini 4 and later, and iPad Pro). On older devices without a barometric pressure sensor, only GPS altitude and accuracy will be displayed. If you have an Apple Watch, check out the new Pro Altimeter for Watch and get all this same functionality on your wrist!

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Pilot: Aviation Altimeter

"Used this app last weekend. Was within +/-40 feet of my Garmin for the 2.5 hours flight. (FAA standard: +/-75 feet)"--- Xploring Alaska, bush pilot. "Very Impressive. It was pretty much spot on with my indicated altitude. According to the FAA refs, since the reading is within 75 feet of my altimeter, it pretty much IS spot on. This app would make a great emergency backup in case of an altimeter/ pitot-static system failure." --- Brian, private pilot and owner of a Piper Cherokee. "That's why I was surprised. At 35,000 feet, it was measuring the cabin altitude, which is what a real altimeter would measure inside the plane [...] Tonight it worked just perfect, I recorded it as we were climbing and the cabin altitude as well." --- David, Airbus captain. ------------------------------- 1. Just Like Professional Aviation It is a real pressure altimeter using the built-in air pressure sensor (barometer) in your iPhone. Pressure altimeters, also used in professional aviation, are among the most accurate types of altimeters. Here is simple way to test out the app--- open it in an elevator to see how fast and accurately it responses! 2. Why a Pressure Altimeter? A pressure altimeter is incomparable to some apps that determine your altitude by using only ASTER and/or GPS. GPS is not accurate in determining true altitude, which often results in ~100m (~300ft) error; while ASTER is a library of elevation maps of the Earth. It is a map rather than a true altitude-measuring device. Being a map library, ASTER is problematic when you are not on the ground surface of the Earth— for example in an underground cave, inside a high-rise building, on a hot-air balloon…etc. 3. A True Altitude-Measuring Device It uses your iPhone’s barometer (air pressure sensor) to detect the surrounding air pressure hence determine your altitude. The principle is that the higher the altitude, the lower the air pressure (in other words: the higher the altitude, the thinner the air which makes it hard to breathe; the lower the altitude, the more “abundant the air is”). That’s how air pressure is used to determine altitude. 4. Accurate Like the Real Thing Since air pressure at the same location with the same altitude varies everyday due to different weather conditions, the variation would cause a small error in altitude reading. It is negligible for leisure users but crucial for pilots (and serious nerds). Therefore, in real airplanes as well as in our app, there is a feature for you to adjust the air pressure compensation. You may find more instructions inside the app. ------------------------------- *Disclaimer* This app is only for leisure entertainment purpose. Although it is designed and engineered for best accuracy, this is NOT a FAA certified flying instrument hence it should NEVER be used for flying or other high-risk activities such as skydiving, hang gliding, hot-air-ballooning etc… Always use certified instruments for the high-risk activities, do not use this app as a replacement. Meanwhile, we hope you enjoy the pocket-sized aviation altimeter!