On 13/11/2020 17:44, michael adams wrote:
All real arborists will be secured by ropes from above and wouldn't
be seen dead, anywhere near a ladder.

Plenty still use ladders to access the crown,


Either literally or metaphorically.
You throw a rope between an overhead branch and the trunk and climb up the
secured rope, using one or more pairs of ascenders. Ratcheted devices
for feet and hands. Then secure yourself on a higher branch on the way
up, and repeat as often as necessary.

It's actually quite unusual to need a throw line (light twine with a bag
weighted with lead shot) to access the crown). on a take down spikes and
strops is the preferred method on our team (we're a bit long in the
tooth with the supervisor being 64 and climber 42, I'm a geriatric brash
dragger when needed).

The climber usually uses a doubled rope technique and a positioning
device called a zig zag, the supervisor still uses a prussic knot on a
doubled rope.

Single rope technique is used by a lot of young climbers but after
access they will often use doubled rope for positioning plus a strop for
safety.

A single rope tied at the base for access doubles the stress on the
anchor point in the tree.

What you describe is the standard doubled rope technique for access but
the use of foot and knee ascenders is only needed for single rope technique.