Thank you for flying Umbrasyl Airlines. We hope you enjoy the embrace of your seat and the atmosphere provided by our one-creature flight crew. Please settle in and hold your breath for 66 minutes as our very experienced pilot guides you straight to your destination.
Okay, but seriously. Thanks to the work of @MCBE117 and @Trograf on Twitter, we can estimate that the distance from the battle field to Gatshadow is approximately 20 miles (105.600 ft). Using the calculations of the fastest methods of travel (all with Dash actions):
Umbrasyl (as the dragon flies)
- 160 ft per round
- 1600 ft per minute
- 105,600 / 1600 = 66 minutes
Broom of Flying (as the broom flies)
- 100 ft per round
- 1000 ft per minute
- 105,600 / 1000 = 105.6 minutes
Keep in mind that this assumes that the map is entirely to scale. Based on past descriptions, Umbrasyl has crossed the distance in significantly less time, and it is probable the same will hold true tonight, as well.