I've got a pretty good view to the north-east from my location to the north of Heathrow. I've set up some markers on the map to help me visually identify the aircraft inbound and outbound. These 4 red radial lines mark my field of view to the left and right and the 2 lines between these correspond to 2 prominent chimney pots on nearby buildings. So, I watch the aircraft on the RB screen and when they cross or approach these lines, it's over to the window to visually identify the aircraft through the binos. Very simple, but it works very well :-) It's a bit more cloudy today, but I'm still seeing some traffic through the gaps. Note that I've used the altitude filter to only see traffic below 15,000 ft and normally the radial lines are not this bright, but I've changed the colour to make them easier to see in the screen shot.