.....
The South Vietnamese even fought an actual
naval battle with the PRC in 1974 over the still-disputed Paracel Islands in the South China Sea. North Vietnam reiterated the Vietnamese claim on the islands in 1976.
.
Ah yes, the forever disputed Paracel Islands (and the Spratleys too).
We occasionally flew from Yankee Station in the Gulf of Tonkin, to Cubi Pt. in the PI. near the hostile islands.
Sometimes we flew on wing with aircraft that had some 'better navigation' than we. But most of the time we were alone in the F-4s, and it was therefore pure dead-reckoning over-water navigation to Cubi that stressed our max range. But the main thing we feared (aside from not finding the Phillipines on a long, DR flight) was passing too close to the Paracel Islands.
It made no difference if the Vietnamese or the Chinese were there, they alway fired on us if we cut the corner too close. It was a very dangerous place to fly near if you unfortunately, "cut the corner."
So we flew, time/distance southerly, until we thought we were clear of the islands, then we turned toward the PI. The hoped-for massive "towering Q" on the nose was always a relief, because it reassured us our DR course was roughly correct and on track. (Massive buildups were prevelant over land in the South Pacific, much more so than over open sea. Ergo, thunderheads on the nose indicated (hopefully) land, until we could finally come within TACAN range to confirm, and to adjust course to Cubi Pt. Only then could we rest easier.
... and start thinking about San Magoos, etc.