One site going to give you the real estimated flight time for this route.
GPS do not work over the oceans, as they are ground based.
All exploration that has been done by Flat-earthers confirms the accuracy of this map. I can not prove something on your behalf, you have to prove things yourself.
Flight Time
11 h and 9 m
Flights from Sao Paulo and Luanda take around 11 h and 9 m minutes, however this flight time can depend on other factors too
https://www.edreams.co.uk/flights/sao-paulo-luanda/SAO/LAD/#/
One site going to give you the real estimated flight time for this route.
GPS do not work over the oceans, as they are ground based.
All exploration that has been done by Flat-earthers confirms the accuracy of this map. I can not prove something on your behalf, you have to prove things yourself.