Military appears to be testing system to disrupt GPS over wide area. Large spread GPS outage in CA and southwest

Hi Mr. Wiley:
I presume you are a "flyer" (meaning someone who rides in BACK of a "Part 121" provider), and thus, for lack of understanding about what we do in aviation, are frightened at the possibilities you raise.

Let me assure you that you "flyers" are perfectly safe. We who drive airplanes around have any number of ways to avoid the kind of danger you propose.

I am not entirely sure I understand what you mean by "FL120". Are you concerned about people driving airplanes around at something called Flight Level Twelve Thousand Feet" around the SIerra Nevada? Or did you mean "Flight Level One Hundred Twenty Thousand Feet...?

If you meant 120,000 ft., don't worry....the highest peak out here in the south-west is Mt. Whitney...around 14,000 ft. So in that case, you are perfectly safe.

If you meant twelve thousand feet...again..don't worry...we in the aviation community have all manner of rules, regulations, and proceedures for "IFR" ( presumably you meant INSTRUMENT FLIGHT RULES ?) We have things called "charts" - these can either be paper or electronic that are independent of the GPS system. They tell us what "MINIMUM OBSTRUTION CLEARANCE" altitudes are in any given sector. Over the Sierra Nevada, for example, those MOS's are high enough over the highest peaks to keep you perfectly safe!

So - absent the VERY statistically rare case ( dosnt seem to happen any more what with more people flying IFR and knowing what they are doing)...you are perfectly safe.

As far as a shut-down of the entire GPS system in any given sector...- yes...that will happen later this month for a short time for a test of GPS security... - but it dosnt happen without weeks of prior warning. We have what we call "NOTICES TO AIRMEN" which we are required by law to check.

Of course there is the remote possibility of a electrical failure on board an aircraft, disabling the GPS receivers in that aircraft.

Again..not to worry....I cannot imagine ANY responsible "airplane driver" operating IFR without multiple back-ups. For example..even in my own modestly equipped aircraft, I have two separate VOR / ILS receivers in addition to my Garmin 750 GPS "moving map" / ADS-B display.

Everyone I know carries a "hand-held back-up" I carry a hand-held Garmin 500 (look that up on Garmin's "site".....may put your mind to ease about how things work in aviation ) AND I carry an I Pad. Which gives me all manner of information independent of the GPS (although obviously the info. is more complete when it is receiving GPS).

So again...not to worry...we have totally independent systems NOT dependent on an aircraft's electrical system and/or GPS.