Here is a link that I think should be required reading for Drone pilots if you dont have prior GPS training from FAA/Govt pilot training

GPS is not an infalible and all be all navigational system

its a single tool in a whole list of navigational aids and in real aircraft only provide a piece of a navigational solution... its never blindly trusted.. and for good reason.

https://www.gps.gov/systems/gps/performance/accuracy/

thank you , good reading .

Thank you, excellent document.

Very good reading, should definitely posted STICKY!

Thanks for sharing,
Wolferl

Interesting reading.. thanks for sharing this with us !

Great stuff and sobering read regarding degradation by obstacles, thanks!

a big takeaway here ... and the FAA doesn't even mandate it specifically for 107 commercial ops although they allude broadly will accomplish checklists.. is that a drone pilot should most definitely check GPS notams as part of a 'pre-flight' for a given area/day

I also check the space weather pages to get and idea of geo storm intensities..

some of the newer drone checklist apps do quite a lot with weather, winds aloft not just surface, Kp factor AND the predicted reduction of satellite lock based on that Kp.. have not found one that references GPS notams though.. I think they just use predicted GPS ephemeris data to estimate the visible satellites overhead at a given time but doesn't necessarily know the health of those satellites ..

anywho .. its just scratching the surface of GPS.. a good drone pilot that doesn't want to have fly aways should do a deeper dive into how GPS and MEMS gyros / compasses work...

DeuceDriv3r Posted at 2018-10-18 09:11
a big takeaway here ... and the FAA doesn't even mandate it specifically for 107 commercial ops although they allude broadly will accomplish checklists.. is that a drone pilot should most definitely check GPS notams as part of a 'pre-flight' for a given area/day

I also check the space weather pages to get and idea of geo storm intensities..

For the record, the Spark uses GLONASS and GPS.  It might also use the Chinese version of GPS.  It uses them all at the same time.  That is why the Spark expects to see a minimum of 12 satellites over head.  12 would be a crazy amount of GPS satellites to see from one point on earth.   

Gunship9 Posted at 2018-10-18 09:23
For the record, the Spark uses GLONASS and GPS.  It might also use the Chinese version of GPS.  It uses them all at the same time.  That is why the Spark expects to see a minimum of 12 satellites over head.  12 would be a crazy amount of GPS satellites to see from one point on earth.

true .. but that doesn't change the fact that GPS/Glonass or what ICAO terms GNSS notams should be checked


it also doesn't materially change the effects that are discussed on the GPS page referenced.. as with most russian and chinese tech.. it was stolen from the US so it works mostly the same way.. although GPS is still more accurate than Glonass except in some of the much higher polar areas..

a drone operator still must be acutely aware since there is NO OTHER nav source unlike a real aircraft that has pure inertial positioning, and ground based navaids..

Hmmm I have a day off tomorrow, weather looks good, but a KP of 2 and have forecast app says don't fly with 11.8 says. Would you guys fly? Only plan close in vlos flights. What do you think ? Thanks for advice.

djiuser_6skJaeLno6Ca Posted at 2018-10-18 10:28
Hmmm I have a day off tomorrow, weather looks good, but a KP of 2 and have forecast app says don't fly with 11.8 says. Would you guys fly? Only plan close in vlos flights. What do you think ? Thanks for advice.

a Kp of 2 is pretty low

general consensus is sats 12+  

I have found that once in the air, if I am not around tall trees and can use sats that are 10-20 degrees above the horizon that sats are usually above the forecast number once airborne

if you are LOS and can see it clearly enough to at least station keep until sats come back it should be ok