Airlines love plummeting oil prices, right? Not always. The fall in the price of the black stuff may mean cheaper fuel in the long run, but it’s also resulted in a headache for Portuguese carrier TAP SGPS SA. TAP flies frequently in Angola, but the Angolan kwanza has slumped along with oil prices. So TAP doesn’t want to be stranded with a load of kwanzas. So this week it announced on its website that fliers temporarily won’t be able to buy tickets in Angola—unless the trip starts there. One dollar now buys almost 105 kwanzas, an increase of more than 7% over the last six months, brought on by a nearly 55% fall in the price of both Brent crude and WTI light sweet crude over the same period. Earlier this week, the Angolan cabinet presented a revised 2015 budget to Parliament in which it trimmed its assumed oil […]