Modtran

Insufficient updates for developer products can cause Modtran to crash. Be sure to regularly install the latest software updates.

Restarting your computer can resolve numerous common problems, so it should be the initial step before changing any software-related settings.

Setting a default program by file type in Windows

1. Take the first step by right-clicking on your file. Next, select "Open With" and then choose "Choose another app" from the available options;
2. In the pop-up window, find and select the Modtran application from the available options;
3. Make sure the "Always use this app" checkbox is checked and click "OK" to confirm your choice as the default app for opening files.

Change the default app for a file type in Mac

1. Right-click or Control + left-click on the desired file to open a menu of available actions;
2. Select "Open in application" and click "Other";
3. At the bottom of the window, you will see the "Enable" menu. It is already set to the default option, "Recommended Programs";
4. In this menu, select "All Programs" and search for Modtran. Check the box next to "Always open in app" to make it the default option.