This looks like Joe's "The ADS-B-Receiver Project" (www.adsbreceiver.net), which I also run. This is a wonderful set of scripts which installs and sets up many ADSB packages typically from their sources on Github. It includes the Plane Finder Client software which it feeds in beast format from...
My new setup has been stable for over 12 hours, just checked this mornings peak traffic hour 06:00 GMT.
Plane Finder Radar: ADS-B Positions = 70699, Positionless Reports = 10769
Raspberry Pi 3 + FA RTL: ADS-B Positions = 72561, Positionless Reports = 19467
Both sharing the same antenna.
My PFR unit arrived today and is working. Installation could not have been simpler - the hardest bit was opening the box.
I have been feeding PF for a while using a F1OPA /F5ANN active antenna, a FA RTL dongle, and a RPi3. I am in a busy area not far from London Heathrow in the UK.
Are the planes disappearing below your horizon?
I live within 10 miles of Heathrow and loose most planes around 300 ft
If you are close to the airport then probably heightening your antenna may be the simplest solution.