I was researching worldwide airway designations when I stumbled upon this airway in Brazil: G678 with an MEA of 15,000 feet and a distance of 594 NM (nautical miles) between navaids.
It's drawn between the BSI and ATF VOR's. Mid-airway around S12°50.12' W52°4.38'.
Flying at 15,000' with BSI at elev ~3500', the line-of-sight is 166 NM. And as far as I know a high altitude VOR reaches out to 130 NM, maybe more, but certainly not 300 NM, right?
The "G" designation is for a non-area navigation route per ICAO annex 11. So it's a non-RNAV route. It's even colored black (vs. blue) on skyvector.
A, B, G, R for routes which form part of the regional networks of ATS routes and are not area navigation routes.
So, how can it be flown?