EAI WebApp v2.8
Weather/ NOTAMs & E6B Tools

EAI Pilot Tools Web Application

This WebApp is an addition to our extensive site and focusses on the aviation calculators and weather tools we provide on our pre-flight information, weather and navigation pages but now aimed towards mobile devices.

Running as a WebApp means that these tools are easier to use, device independent (i.e. iOS, Android, Linux and Windows compatible) and some tools even work when you are not connected to the Internet!

The app is also installable on the home screen of your device, your browser will notify you if that is possible. With Apple's Safari you need to tap the share button to add the app to the home screen.

Online Tools

You will need a working Internet connection (LAN, 3/4/5G or Wifi) for these to work.


Notices for Airmen (women too) are an important piece of last minute aeronautical information to be obtained during the pre-flight phase. Our tool reads an user supplied comma / space separated list of ICAO airfield codes and retrieves their NOTAMs from the Defense Internet NOTAM Service (DINS).

Surface Analysis

We have a number of forecast surface analysis maps for several regions available. These maps open in a separate window on your device and are sourced from NAV Canada, Aviation Weather (US), Met Office (UK) and the Bureau of Meteorology of Australia.


Current weather through METAR and TAF forecast is sourced from aviationweather.gov and retrieved through Aviation Weather REST API (AVWX) where data is sanitized, translated, error corrected and certain fields added (for example: flight rules). It is restricted to one (1) airport per request to limit the amount of data shown on the page. If a station does not report a TAF, this field will be omitted and a message shown in the notification bar. Some meteorological data is saved for use in our other calculators.

The METAR/TAF are available in two formats: raw and translated. We also provide a color decoding table to assist you with assessing weather. An alert is shown should the AVWX server not respond within a certain time period.

Keep in mind: TAFs are updated every 6 hours (occasionally 3) and are valid up to 24 / 30 hours. METARs are normally generated every hour and, if required by circumstances, every 30 minutes (SPECI). They may also include a forecast TREND valid for 2 hours.

E6B Calculators

Pressure / Density Altitude

Most performance calculations start with determining the actual pressure altitude the aircraft is operating. This is referenced against the ISA 1013 hPa pressure level. The current pressure lapse rate is also taken into account for the conversion to density altitude.

To correct for the mostly non-standard temperature at the current pressure altitude, we apply a correction factor of 120 ft for every degree the OAT deviates from the ISA temp at that altitude.

The values of this and other calculators are saved on your device during the session and will be pre-filled in several other calculators, notably in the conversion tools for ease of use. Pressing 'Clear' in this calculator will erase the saved values.

Runway Cross / Headwind

All aircraft have a published demonstrated maximum crosswind limitation which is determined during the test and or certification flights of the aircraft. Pilots should adhere to this limit. This calculator shows crosswind and headwind component with regards to the selected runway heading and wind speed / direction. The crosswind will show colored warnings above 15 and 20 kts, headwind also shows a colored red warning in case of a tailwind (negative headwind) and when the crosswind angle exceeds 45° and 60°.

Weight / Mass & Balance

For quick W&B assessments we wrote this generic unit-less calculator for two and four seat aircraft. Just fill in the grey fields and use a point (.) for decimals and zero (0) for empty fields. This should work most of the time.

VFR Navigation Tools

These tools helps you with completing the navigation flight log. With calculators for estimated True Air Speed, a pre-flight Heading, Wind Correction Angles, Ground Speed and Course Deviation calculator. Complimented with a calculator to obtain the reverse: your Course and Ground Speed during flight.

Our Time, Speed & Distance tool calculates any combination of these. Helpful for fuel and diversion requirements. The Fuel Consumption tool is unit-less and is ideal for calculating fuel required per leg in minutes or hours flight time for your navigation log.

Conversion Tools

Converting among several speed & distance units, temperature, pressure and dew point vs humidity with cloud Level or fuel and weight conversions are usually done with a separate calculator, if you are familiar with the formulas and constants. Here we present our own neat little conversion tools.

In winter time, the combination of low temperatures and wind can be very dangerous for our bodies, the Wind Chill calculator and table from NOAA show this clearly. Do take precautions!

On the contrary, during summer time with temperatures above 26 °C or 79 °F and relative humidities above 40 % the heat felt is more harsh than it really is. The Heat Index calculator demonstrates this very obviously.

Technical Stuff

The pressure/ density calculators are based on the following formula's and constants:

Pressure Lapse Rate = 96 × ( T in Kelvin) / QNH

Pressure Altitude = Altitude + (1013 - QNH) × PLR

Density Altitude = Pressure Altitude + (OAT - ISATpa) × 120

Where: ISA QNH is 1013 hPa (29.92 inHg), Temperature is 15 °C at sea level, decreases with 2 °C/1000 ft and Celsius to Kelvin differs with 273 °C and pressure drops 1 inHg per 1000 ft.
These are based on the approximations used in aviation text books and exams. All calculations use celsius for temperature and hPA (hecto Pascal) for pressure as reference.

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