Will a helicopter search help find a lost dog?

My dog disappeared at Owens River Gorge near Bishop, CA. She is a black 40 lb dog, 17 years old and deaf. She gets around very well but she is more clumsy than she used to be and had a stroke a few months ago (that she recover from well). I have searched everywhere for her but can find no sign of her. The area where she was lost is mostly, flat arid land with lots of very low shrubs but no trees, with some cliffs and gullies. I'm worried that she may have fallen down a cliff in a place where I can't see her. I am thinking about hiring a helicopter to search for her, but not sure if that will be effective since she is black and blends in with the rocks and shadows in the landscape. Does anyone have experience with search and rescue using a helicopter? Any ideas for how to better search in this kind of terrain? (I have already done all the usual with posting flyers, newspapers and radio announcements, contacting shelters, etc). Thanks!