The current NZ regulations just say 5000m. Australia the same. The "all directions" requirement, however, is implicit.
But I have just twigged as to what your argument might be. Is it that when they levelled out at 2000/1500 feet, they could see well over 5000m ahead? So when they were miles away from the mountain and if a black helicopter came around from the base, they would have seen it easily? Is that it?