The helicopters themselves have been seen in areas where UFOs were reported, in many countries. In some of the more interesting accounts, the mystery helicopters were seen with UFOs or shortly after UFOs were sighted.
In a documented Mystery Helicopter wave in England, accounts place oriental appearing occupants in a unidentified chopper. Slant-eyed, olive skinned, oriental seeming occupants have been a staple at the heart and at the periphery of UFO accounts for years, significant numbers of the infamous 'Men in Black' (MIBs) have a similar appearance, but very often the are seen as very pale and gaunt men who are sensitive to light.
In "Stigmata", (fall-winter 1978) Tom Adams outlines the most prominent speculative explanations, accounting for the mutilation helicopter link, including the following possibilities:
Mystery Helicopters and Mutilations
Normally the mystery helicopters belongs to the DELTA/NRO division. For a normal mutilation research mission they send one helicopter with a team of seven agents and two Remote Piloted Vehicle, (RPVs). The RPVs are small devices of look-a-like small saucers of three (3) feet in diameter and radio controlled.
Surveillance Devices
Airborne Remotely Operated Device, AROD(THE RPV)
NOTE: This vehicle was created by Aerojet Electro-Systems in California
The RPVs also carry a surveillance robot Airborne Remotely Operated Device (AROD). A flying pizza with a tail, three (3) feet across, carrying a high-tech video camera aboard. Also surveilling the surveillance device from above, is a device known as a High-Altitude Long-Endurance Drone (HALE).
HALE is designed to reach altitudes up to 100,000 feet. The device is powered by microwaves from the main helicopter.
The Hale(ADR 238F)
The Teledyne Ryan Aeronautical Corporation is responsible for the mysterious Helicopters or 'XH SHARKS', as they refer to them.
The TRA, SN-75(XH-75D)
I believe a cover-up of the capacity of this helicopter, is operating which overrides the real and total capacities and capabilities of this helicopter, but the following
is only what I've been able to learn, and may not be the total capacity and/or capabilities.
Some helicopters (XH-75D Type) also have a Gravitational Electromagnetic Projector to create a "Cocoon" around the helicopter as a disguise. A 360 degree global arc with a radius of fifty (50) feet, more or less, provides a photonic force-field.
A black Helicopter (XH-75D Type)
When activated, turns into a UFO, as shown below, with no inertia and no acceleration effects.
This provides 82% Higher protection against attacks.
When used during a normal Mutilation Research Mission, the XH-75D Type black helicopter carries a crew of seven agents, two (2) RPVs, and one (1) HALE drone.