N377RA Chinook is an aerial firefighter.
It is likely dropping off adsb due to low altitude terrain masking of transmitter.
The smaller Bell 407 is probably acting as on scene commander controlling the firefighting from a higher safer altitude.
https://aerialfiremag.com/2024/01/11/helitak-firefighting-equipment-receives-stc-for-ft-11k-ch-47-aerial-firefighting-tank/