Looking through the lens, I thought 'Tachinid'. Thinking I might have found something remarkable (later I noticed that quite a few images exist on bugguide.net) I consulted the following references:
1) Cole & Schlinger, The Flies of Western North America (UC Press,1968), to get the genus.

2) A Cornell Univ.site, with images of T. pennipes: 1
The top image of an 'adult' looks similar to 'my' insect, including the orange leading wing edge, as well as the clear margin. The female shown at the foot of that page has a black abdominal tip (T4-6). The male shown to emerge from puparium looks all orange (though T6 isn't visible). Its wing -at least the underside- shows some orange not visible in the female.
Even though both male and female are dichoptic (eyes separated at the top), I wonder whether a slight sexual dimorphism exists in wing and abdominal coloration.

3) A French site (T. pennipes is reported from the Midi of France; introduced to southern Europe acc. to Paul Beuk ) shows a male/female photo (2), with only the male's abdomen clearly discernible. It also sports the orange leading wing edge (the female has some of that,too), and the all-orange abdomen.
So, perhaps this fly from Eaton Canyon is a male? I guess one would have to see alot more of this fly.