The mystery helicopter issue — mulitiple flights per day have been going over the hills from Chantry Flat to Millard Canyon — seems to be solved.

We were forwarded an email from Graham Breakwell of the US Forest Service, who explains what's going on with all the chopper activity — it's Southern California Edison at work:

SCE are focused on inspecting/maintaining their road-inaccessible Transmission Towers in the Millard Canyon vicinity:

i) probably 10 days of flying, Monday – Friday. from 7am to 5 pm, between Wednesday 11th and Tuesday 31st July;

ii) Chantry (Big Santa Anita) for landing and refueling and Chaney Trail for hovering (70’ up?) and collecting personnel on a 75’ rope;

iii) One helicopter and 2 pilots;

iv) 3- 4 flights a day into Chaney Trail, each hover for <3 minutes and then deliver personnel to the tower. Helicopter at rest and refueling will be at Chantry;

v) Chaney Trail hovering site will have a water truck to water down the area which is between the two LAWC water tanks; and

vI) Have security personnel posted at: a) The meeting point of the dirt pathway/trail crossing Chaney Trail (at the bend/elbow in the road) below the lower water tank, and b) another on Mt Lowe Road at the upper tank where a road starts and then descends to join upper and lower tanks.

Now, if we could only get an explanation about the mystery booms …