"FLIGHT SIMULATOR":
5 unbroken double unders
10 unbroken double unders
15 unbroken double unders
20 unbroken double unders
25 unbroken double unders
30 unbroken double unders
35 unbroken double unders
40 unbroken double unders
45 unbroken double unders
50 unbroken double unders
45 unbroken double unders
40 unbroken double unders
35 unbroken double unders
30 unbroken double unders
25 unbroken double unders
20 unbroken double unders
15 unbroken double unders
10 unbroken double unders
5 unbroken double unders

You MUST stop in between sets (the rope must stop).
Once you miss at one level three times in a row, work back down the ladder.

Notes: I did this with singles. Tripped up once on round of 45 on way back down ladder (at rep 44!). Total time was 7:58.