Circuit training question
I'm trying to understand how they developed the "3 second per 100 feet" rule for timing the turn to base from passing the runway threshold on the downwind leg. I'm finding that I'm way too high once I turn to final.
Flying the downwind leg at 1500 AGL, the formula tells me I turn after 45 seconds. Considering that I need to be at 4.5 miles DME turning to final at 1500 AGL, this would mean I need to be flying at 313 kts (or 360 MPH) if I'm to be 4.5 miles beyond the threshold in 45 seconds. But my average gear down flaps 15 speed is probably 150 kts, so it feels like I should be applying a 6 second per 100 feet rule, no?
Appreciate the help!