I would also like to see this feature, and an associated audible alarm option for aircraft within a chosen distance and below a chosen altitude. This would be a very useful option for UAV pilots as a warning of nearby aircraft.

+1 for me!!

@robsymax @Bdavy92960 @JonMurphy
Hello,

I have created a dev branch that implements a distance slider to filter the display of aircraft.
Pull request #249 is open however the raw files can be downloaded from the public_html directory of my dev branch here : https://github.com/oam7575/dump1090/tree/dev-distance-filter

If you would like to manually upgrade your installation do the following.
Backup
Backup these files from your current installation

• index.html
• config.js
• planeObject.js
• script.js
• style.css

Upgrade
Replace the listed files with the versions in my dev branch.

Hello, @robsymax @Bdavy92960 @JonMurphy

Distance and Altitude alert beeps have been implemented in my pull request #250.
#250 also includes the distance slider previously implemented in #249.

As per my previous comment, you can manually upgrade your installation by downloading the raw files from the public_html folder of my branch : https://github.com/oam7575/dump1090/tree/dev-distance_alert_altitude_alert

Note : The changes for the alert beeps are in a separate branch