E6B Calc: questions pilots ask before installing

Yes. Free to download, no ads, and every calculation, conversion, clock, timer and the keypad are free with no daily cap. E6B Pro is one optional purchase, not a subscription, and it adds unlimited METAR/TAF decoding, unlimited use of the analogue wind wheel, unlimited exam sessions, more than one aircraft in weight and balance, your full history and two widgets.

Yes. Every calculator and the METAR/TAF decoder run on the device, no connection needed. The internet only gets involved for the App Store purchase itself, iCloud sync and the support email draft.

No. You copy a report from your briefing source and paste it into the METAR & TAF Decoder, which decodes it offline. The widgets do not fetch weather either: they read the home field observation you typed.

It runs the ICAO standard atmosphere equations, not the classroom 120 ft per °C rule, and rounds to the nearest 10 ft. Garbage in, garbage out though: it is only as good as the altimeter setting and OAT you type, and it assumes dry air.

Humid air is slightly less dense than dry air at the same pressure and temperature, so humidity does raise density altitude a little. E6B Calc does not model it: there is no humidity or dew point input on the Density Altitude screen, so on a very humid day treat the answer as slightly optimistic.

It starts from calibrated airspeed. Run your IAS through the airspeed calibration table in your POH to get CAS, then enter CAS with altitude, altimeter setting and temperature. From there it uses compressible-flow equations, so it stays accurate at jet speeds where the simple slide-rule method drifts.

Nobody can promise that. What you may bring into a testing centre is between the testing centre and the FAA, and phones usually get a no. Exam mode is for practice, and for the places where a calculator app is actually allowed: it hides saved history and the METAR decoder, but it does not lock the phone or make it an approved device.

No. It is a planning aid and is not certified for navigation. Cross-check every figure with your POH/AFM, approved charts and official briefings; the pilot in command remains responsible.

No, and that's deliberate. Two airframes of the same model almost never weigh the same once you account for the paint, the avionics swap, the extra battery. You type empty weight, arms, stations and the CG envelope from your own weighing report and POH once, then keep reusing that profile. Free keeps one aircraft.

It never uses location. Coordinates for great-circle distance and sun times are typed by hand, and the app requests no permissions at all: no location, camera, microphone, contacts or tracking.

Yes. Settings > Units of measurement switches the altimeter setting between inHg and hPa, speed between kt, km/h and mph, distance between nm, km and sm, temperature between °C and °F, and fuel between US gallons, litres and imperial gallons. Weight and balance uses its own lb/in or kg/cm choice per aircraft.

The METAR decoder gives 3 free visits that decode a report, and a report that fails to decode costs nothing. The Analogue E6B gives 3 free opens. After that those two screens ask for E6B Pro, while the digital Wind Triangle and every other calculator stay free.

No. It is one payment through the App Store, with a Restore purchase button on the purchase screen and in Settings if you reinstall or move to a new device. The price is shown in your local currency before you buy.

No. There is an iPhone and iPad app and a companion Apple Watch app. There is no Mac app and no Android version.

It has four screens: Crosswind, Density Altitude, Time · Speed · Distance and History. It calculates on the watch with the Digital Crown and can save results to the history you see on your iPhone. There are no watch complications.

Calculations are saved on the device when you leave a calculator with a complete answer, and synced through your private iCloud if you are signed in. Clear history in Settings deletes them everywhere. There is no export, share or print option.

Because numbers are what you type in a flight computer. The keypad has large keys, a plus/minus key that works before or during entry, a decimal point, Clear field, Next field and Done. The iOS keyboard only appears for text such as an aircraft name.