Vortex Ring - 'Settling with power'
The signs of a helicopter encountering settling with power are a vibration in the main rotor system followed by an increasing sink rate and a decrease or loss of cyclic authority, depending on the severity of the condition.[2] The failure of a helicopter pilot to recognize and react to the condition can allow high descent rates and impact with terrain, a frequently fatal accident.
This gets my vote, being overhead XMG at 14k without Oxygen does not.