Need a Ceruleum tank to do a FC airship exploration

[Waeksyn]

"Ishgardian Exploratory Missions
Players can also journey to the Diadem via Ishgardian airships. .... Each player of the party must have a mission ceruleum voucher in their possession, which can be purchased from the NPC Jaquoinie in the Pillars (X:14 Y:10) for gil. One voucher is required for each mission.

Seems to me that the best thing would have been to allow these Ishgardian ceruleum vouchers to also be used for the FC ships (and vice versa I suppose).