EAI WebApp v3.5
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 (32!) are easier to use, device independent (i.e. iOS, Android, Linux and Windows compatible) and some 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.

Navigating the app is easy: to go back to the main page touch the name of the app in the dark grey bar at the top. To go back one page touch the copyright notice or use the 'back' button at the bottom of each page. There is also a button to go back to the home page.

Online Tools

You will need a working Internet connection (LAN, 3/4/5G or WiFi) for these to be able to get current data.


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).

Airport Data

Airport information is sourced from ourairports.com and we show frequencies and runways to be used as pre-flight nice-to-know info. Keep in mind that the relevant AIPs are leading. Our database is updated daily.

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. These charts give you the big picture of weather in these areas.

Station METAR / TAF

Current weather through METAR and TAF forecast is sourced from aviationweather.gov (ADDS) and also retrieved through Aviation Weather REST API (AVWX.REST) where data is sanitized, translated, error corrected and certain fields added (for example: flight rules, pressure/ density altitude and relative humidity). We also cache recent data on our server, just in case the data is requested again before it expires.

It is restricted to one (1) airport per request to limit the amount of data shown on the page. This tool is ideal for a quick weather check at an airport of interest. Take note of the day number we add to the METAR and TAF line, this helps to see if a report was cached or not.

Meteorological data is saved (and timestamped) for use in our other calculators and when you return to this page; pressing 'Clear' will erase those saved values from your browser. Some airports do not publish weather data, in these cases you will only get station information. 'Show Nearest Stations' takes you to the form to request these and their current flight rule status.

Please keep in mind: TAFs are updated every 6 hours (occasionally 3) and are valid up to 24 / 30 hours for an area 5 statute miles around the station. 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.

METAR/TAF reports are available in two formats: raw and translated. We also provide the standard color decoding table to assist you with assessing weather. Please note that these colored flight rules only evaluates cloud base and visibility.

Note that '(expired)' will be shown for stations with cached/ old METARs/ TAFs. Should a station not report any METAR or TAF you will see a message in the notification bar.

Wind Warning!

When winds are 20 kts or higher or when gusts or wind shear is expected, the flight rules tags will be shown with a black border and yellow text. The wind element will also be printed in bold.
Example:  VFR  BECMG 2103/2105 23025G37KT.

We have created this unique feature (we are the first with this type of visualization) to help pilots determine unfavorable wind conditions which are not considered in the flight rules category.


This option will show the flight categories for the past 24 hours. Gives an indication if conditions are improving or deteriorating at the station. The colored bar shows present(left) to past(right), the length of the bar depends on the number of METARs published by the station in the last 24 hours (this varies).

Nearby Stations

This tool locates the nearest stations based on ICAO identifier or latitude/ longitude coordinates (use decimal notation: DD.dd). The list is limited to ten (10) stations and it shows full name, country and distance to given ICAO or LAT/LON coordinates.

Area Weather

In addition to the nearest station information we now provide their current METAR flight rule status. This means that you can easily see actual weather around your location or requested station.

Flight Path Weather

This tool provides you with current weather along your route. It needs weather stations and a distance between 10 and 99 NM from the flight path, should your airport not have weather reporting pick the closest one that does. METAR data from the last hour will be fetched within that corridor.

E6B Calculators

The values of these 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.

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 (29.92 inHg) pressure level. The current pressure lapse rate is also taken into account for the conversion to density altitude. Should you have requested a METAR beforehand those values will be shown here including the station ID. Tapping that ID brings you back to the METAR/TAF page.

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

We have also provided a calculator to obtain the actual altitude you are flying.

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 prefilled values shown in the ID are taken from the last METAR/TAF you requested.

The crosswind will show colored warnings above 15 / 20 kts, headwind shows warnings at 20 / 25 kts and it also shows a colored red alert in case of a tailwind (negative headwind). Also, when the crosswind angle exceeds 45° / 60°  you will also see warnings.

Weight / Mass & Balance

For quick W/M & 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 leave the zero (0) for any empty fields. This should work most of the time. Landing weight and balance has been added too.

VFR Navigation Tools

These tools assist you with completing the navigation flight log. With calculators for precision True Air Speed which includes distance to horizon and Mach number, 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. We also included a Coriolis calculator as this really does affect our flight too, as little as it may be.

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.

Atmospheric/ Conversion Tools

Converting among several power, speed & distance units, temperature, pressure and dew point vs humidity with wet bulb, cloud bases, freezing level in clouds, actual mixing ratio (defined as the mass of the water vapor to the mass of dry air), barometric pressure altitude, potential & kinetic energy, fuel (Jet/ AV & MOgas) and weight conversions are usually done with an aviation calculator, if you are familiar with the formulas and physics constants. Here we present our own neat little tools for atmospheric and standard aviation conversions.

In winter time, the combination of low temperatures (below 5 °C, 40 °F) and higher winds (above 5 kts/ mph) can be very dangerous for our skin and body, the Wind Chill calculator and table from NOAA show this clearly. Do take precautions!

On the contrary, during summer with temperatures above 26 °C / 79 °F and relative humidities above 40 % the warmth 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: International Standard Atmosphere (ISA) QNH is 1013 hPa (29.92 inHg, 760 mmHg), temperature is 15 °C (288 K, 59 °F) at sea level, decreases with 2 °C/1000 ft altitude gain and Celsius to Kelvin differs with 273 °C and pressure drops 1 inHg per 1000 ft.
Dry adiabatic lapse rate is 3 °C/1000 ft, saturated adiabatic is 2 °C/1000 ft, dew point is 0.5 °C/1000 ft. The dry air (relative humidity 0 %) density is 1.225 kg/m3 and the speed of sound is 340.294 m/s.

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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