US Servers
12:30pm UTC, 6:30am CST M-F
8pm UTC, 2pm CST Everyday
5pm UTC, 11am CST Usually fails except once in a blue moon a guild shows up and runs it.
Check “LFG > Central Tyria > World Bosses” for a TT Taxi 30 minutes before the times listed.
I am not affiliated with the guilds so I didn’t mention names.
I’m sure there are later times that don’t fail but these are the ones I go to regularly.
*Note: Game-created portals say "Interact," and player-created portals say "Use Portal.”