On the 29th May 2013 we were treated to five GR4 Tornado passes, amongst other aircraft.
In this video I added the times and the locations for those not familiar with the routes the jets take.
The Mach Loop (also known as the Roundabout to USAF crews) is a flowed one way system. Fixed wind aircraft can only go in one direction, anti-clockwise, whilst rotary wing aircraft can go in either direction.
For the most part, on exiting the Bwlch pass, fixed wing pilots have four possible directions to choose from. They either turn left to Cad and go back into the Loop, they go straight on to Dolgellau, they turn right and head towards Bala Lake or they pull out.
If they choose the first option and turn left out of Bwlch they are likely to appear again through Bwlch a few minutes later. It takes fast jets around 3 minutes to complete a circuit of the Loop, depending on the route they take, a little longer for props. Generally jets only go round the Loop once or twice.