The KochChart Density Altitude Software Tool

News!

KochChart version 4.0.5 has added a new "Air Data" tab. This tab is a table showing some of the input and output values used in making the density altitude (and other) calculations. The table will automatically update if a valid station is selected on the Koch tab, a METAR has been retrieved and the "Auto-Update" feature is enabled.

KochChart version 4.0.4 has added "Auto-Update". Now you can leave your Koch chart, your Altitude chart and your Carburetor Ice Potential chart open, and the graphics (along with the Koch tab) will be auto-updated at an interval of your choosing (provided a valid station METAR can be retrieved).

KochChart version 4.0.3 has added a chart indicating the potential for carburetor icing. This chart is based on the carburetor icing probability chart published by the Civil Aviation Safety Authority (CASA) of Australia.

How does this chart differ from the "new" U.S. NTSB chart? Not a bit. Well, they used different colors, but it appears they adopted the CASA chart. The FAA also has a couple of versions of carburetor icing charts. One is in their "Winter Flying Tips" pub and the other is in the Special Airworthiness Information Bulletin (SAIB) CE-09-35. These charts, when the axes are converted to those of the CASA and NTSB charts, are seen to be different, but not drastically so. The trends are the same. See the comparison below. Click on any chart to enlarge it.

KochChart version 4 has been released! The new version allows the user to export the charts and values from a session as a .pdf file, which can then be sent to your email-enabled device.

Introduction

Welcome! This site is your source for the KochChart educational software tool. This tool compares various estimating methods (including, but not limited to, the Koch Chart) for assessing the impact of density altitude on take-off and rate-of-climb performance. In addition, the tool can estimate the effects of wind, runway slope and runway surface on take-off distance.

This is a free educational tool created to raise awareness about the significant effects density altitude has on aircraft performance. These effects are especially important for pilots flying at high-elevation airports.

Why the name 'KochChart'? This program started as a relatively simple digital version of the venerable Koch Chart nomograph (the roots of which are somewhat obscure). The user would type in key parameters (air temperature and pressure altitude) to produce the chart. But eventually automated METAR collection, others' estimating methods (besides Koch), tables, comparison graphs, and even carburetor ice potential were included.

The algorithms for density altitude effects used in this software were originally developed for light, single-engine, normally aspirated (i.e., not-turbocharged) piston aircraft. They are not applicable to other types of aircraft.

Downloads

You can download the KochChart software at this page. Look for the release with Latest badge after the release name.

Currently, the software is only available for the Windows OS.

Instructions

You can view an instructional video here:

And the software was also featured in a Colorado Pilot's Association webinar, which included a detailed demonstration of the software. It can be viewed here (the software discussion starts at around the 32-minute point in the video):
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KochChart Disclaimer and License Agreement - Not for Flight Planning

By using the software, you agree to the following terms:

Educational Use Only: This software is provided for instructional and educational purposes only. It does not meet the requirements of Federal Aviation Regulation (FAR) section 91.103 "Preflight Action" or any other regulation.
No Operational Use: This tool is not approved for flight planning or operational decision-making. Pilots must always consult their official Airplane Flight Manual (AFM) or Pilot's Operating Handbook (POH) for performance calculations.
License Terms: This software is free for personal, non-commercial use. Redistribution, modification, or commercial use is prohibited without prior written consent from the author.
No Warranty: This software is provided "as is," without any warranties or guarantees of accuracy, saftey, or fitness for any purpose. Use at your own risk.

Supporting KochChart

The KochChart software is free, but if you would care to make a donation to its maintenance and future improvements, you can do so here. There is absolutely no obligation to do so. I hope you enjoy the software, and gain a better appreciation for the effects of density altitude on aircraft performance.
--Jim Greer

Questions and Feedback

Have a question or feedback? Contact me via GitHub
...or use the Contact Form below.