On PHB P 182 it mentions that "While traveling at a fast pace, characters take a - 5 penalty to their passive Wisdom (Perception) scores to notice hidden threats.". It also has a chart for travel pace:
Pace Distance Traveled per... Effect Minute Hour Day Fast 400 ft 4 miles 30 miles -5 penalty to passive Wisdom (Perception) Normal 300 ft 3 miles 24 miles — Slow 200 ft 2 miles 18 miles Able to use stealth
However it also says "Certain special mounts, such as a pegasus or griffon, or special vehicles, such as a carpet of flying, allow you to travel more swiftly."
Does the "Fast" pace on the chart apply to all travel (air, land, sea), and if not, what is the Fast Pace for flying travel. If it matters, assume a base fly speed of 50ft.
If possible, looking for RAW answers and please note references or attach citations. Thx.