Anonymous ID: fdb75a Dec. 31, 2017, 9:30 p.m. No.220704 🗄️.is 🔗kun >>0706 >>220576 Why some flights drop off radar and why flight information might be incomplete. Older planes have out-dated transponders. https:// www.flightradar24.com/blog/ how-we-track-flights-with-mlat/