Regal Flight Paths
The monarch butterfly which annually covers thousands of miles as it travels from Canada, across the US, to its winter quarters in Mexico.
Or
Royal Flight Path
The line from (about) West Bergholt to the Mall over BuckPal �.and beyond?
Answered over and over again in Q&P as Purple Airway
The Purple Corridor is the correct name but that doesn't fit the answer which requires two words of six letters each so most people doing the colours quiz have opted for airway .