For anyone flying across the pond, AskaCFI.com has posted two queries regarding Q-routes: Can you use a Q-route below FL180? (written by Max Trescott) and a follow-up question entitled What the heck is a Q-route? (written by Paul Tocknell) that was asked by a reader who had read the first post. To address the second question, Paul backtracks and gives a useful backgrounder about the three types of airways found in the USA which are 1) VOR Federal airways, 2) Colored Federal Airways and 3) RNAV airways. As for RNAV airways, these types of airways have two types of routes: 1) Q-routes (high – 18,000 feet MSL and FL 450 inclusive) which are depicted on Enroute High Altitude Charts and 2) T-routes (low – 1,200 feet up to 17,999 feet MSL) which are depicted on Enroute Low Altitude Charts.