>type aircraft have capability to detect depth/tunnels?
Ground penetrating radar has limited depth, but gravity mapping shows density (or lack therdof) to much greater depths. There's also commercial products available to find caves, cavities, and bunkers: https:// www.okmmetaldetectors.com/en/okm-detectors/cavity-voids-detectors/
Rumors abound about satellite capabilities but there's certainly airborne capabilities. In the 1990's large areas of the intermountain west were overflown by formations of military helicopters five or six abreast in grid patterns for weeks/months at a time, sometimes accompanied by sub hunter aircraft trailing long antennae. They often flew at night, but not all flights were in the dark.
t. witness