It may surprise some just how much protection there is. This is TERPS but I would think PAN OPS is similar:
What surprised me the most when I first read up on holds was the amount of protected space on the non-holding side.
PANS-OPS is indeed similar, but distinguishes between a holding area and an entry area. (Maybe TERPS does too, it just wasn’t mentioned in the video.) Once the aircraft is established in the hold, only the smaller holding area needs to be protected.
In fact, PANS-OPS provides quite a bit more protected space than TERPS.
In general, a hold needs to be big enough for a 747, so it’s no surprise that the protected area is as big as this, and I think most people are surprised it goes all around to that extent.
This was the explanation I got when doing the IR, as to why we are almost never put into a hold: because it mobilizes too much air.
A slight detour on vectors, and playing with airspeeds for jets, is much less expensive and very simple operationally.