How to fix loading issues after clicking "Fly" or "Ready to fly" button

The steps below are particularly useful when the sim freezes or crashes after clicking the "Fly" or "ready to Fly" button.

PROBLEM WITH PERIPHERALS OR CUSTOM PROFILES

1. Close Microsoft Flight Simulator
2. Unplug any peripherals you will not be using during your flight.
3. Uninstall or disable plug-ins such as FaceTrackNoIR or TrackIR.
4. Plug the peripherals you will be using
5. Launch the sim 
6. Go to Options > Controls Options
7. For each peripheral plugged into the sim with a custom profile, click on "Preset Manager" then "Delete" then press "Yes"
8. Click "Fly" and try again

If you're able to launch a flight after deleting the custom profiles of the peripherals, simply rebuild a custom profile from the default mapping or use the default mapping.

DELETE CORRUPTED FILES

Some corrupted files may be causing the issue.  To avoid doing a clean install, delete the following folders:

• SceneryIndexes
• SceneryCache
• DCE

Depending on your version these folders are nested by default inside the following folders:

MICROSOFT STORE VERSION

C:\Users\YourUsername\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache

C:\Users\YourUsername\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalState

STEAM VERSION 

C:\Users\YourUsername\AppData\Roaming\Microsoft Flight Simulator

RETAIL DISC VERSION

C:\Users\YourUsername\AppData\Local\MSFSPackages

NAVIGRAPH

If there is an issue with validating your Navigraph account, it will cause the sim to freeze upon loading. Uninstall Navigraph and use NavData Nav Center to remove the Navigraph database then try again. If the problem is fixed, reinstall Navigraph.

RESTORE THE SIM TO ITS VANILLA STATE AND TRY AGAIN

If you still experience a system freeze or CTD when clicking the "Fly" button despite deleting the custom profiles and uninstalling Navigraph, restore the sim to its vanilla state.