Flight Control HD

The 'Most Aircraft on Screen' will be the point where you have filled up the airspace and so no more aircraft can be sent in. I got this whilst going for "Perfect Timing", as having not landed anything for 3 minutes, unsurprisingly the airspace got a little crowded. I'd recommend using a big airfield for this too (maps #6, #7 and #9 seem to be best) since the aircraft seem a lot easier to control when you have more airspace to work with. After the warning has popped up for the 20th time, your trophy will pop!