Observed her entering & exiting her burrow (exiting by rearing out), flying about 50 cm away from the burrow on a diagonal, taking her ~ 30 cm from the ground. She then turned around, flying back to the burrow to repeat the same exercise.
It took me a while before I realized that she carried excavated material, dropped it away from the burrow, then returned to excavate some more. I spent about 30 instructive minutes watching what she was doing. Now I'm eager to read some more about these fascinating insects.
When looking at the specimen, saw the feathery palps forming a basket of sorts, I realized that I must have a Pterocheilus (I recalled what I had learned from Richard Vernier's comments a few years ago).
The feathery palps are evidently being used, basket-like, to carry excavated material away from the burrow.
The burrow is located in a sandy bank of Coyote Wash.