Exploratory Mission

[Waeksyn]

As for FC transport to the Diadem, it was one Mission Ceruleum tank per airship. I'm 90% sure.

From the patch notes:

Free Company Exploratory Missions
When undertaking exploratory missions using a free company airship, players must form a party of at least two people. Players can also form an alliance of up to twenty-four players. There are no role requirements for entering The Diadem as an alliance. Each party or alliance member must have a tank of mission ceruleum in their possession, which can be purchased in exchange for company credits. One tank is required for each mission

Each person needs a tank of mission ceruleum.

[HakuroDK]

From the patch notes:

Each person needs a tank of mission ceruleum.

Well that's just silly.

[GatorWPB]

...and SE was worried about people being unhappy with the lockout? Devs should have realized what a problem this will be for small FCs without a huge bank of FC points. We spent a bunch just getting our airships.
and how does it even make sense that everyone would need a tank, not just the party leader?

[Moonleg]

From the patch notes:

Each person needs a tank of mission ceruleum.

The big question is whether that's a mistranslation from party LEADER rather than party MEMBER.