Peter R. wrote:



At airports without radar coverage for the approach, only one aircraft will
be cleared for the published approach at a time. Other aircraft inbound
will be placed in a hold well outside of the approach until the aircraft on
approach cancels IFR, either in the air or on the ground.
At some locations timed approaches permit more than one approach at a
time, provided the holding pattern meets criteria and the missed
approach does not conflict with the inbound tracks.

Timed approaches were once used a lot, then over time diminished in
their use, and now they are on the increase again.