New global and high visibility service, without IPv6 service. The future is apparently briefly visiting the elsewhere.
As the CIA has already nicely cleared the issue for travelers, if something is done at an aircraft, is is not really a concern of any jurisdiction. Please enjoy the total freedom of an airborne wifi network, semi-responsively.
For quality IP6 connectivity, you also need to accept the multicast address space in INPUT chain, or at least parts of it. Good old ICMP is also nice, your policy allowing:
ip6tables -A INPUT -d ff00::/8 -j ACCEPT # Multicasts are necessary and nice
ip6tables -A INPUT -p icmpv6 -j ACCEPT # ICMPs make us all quite happy
For example, the IPv6 replacement of IPv4 ARP is performed using IPv6 link-local multicast, among other thingies.
Firewall policies on (even the upstream) links must understand the IPv6 specific requirements for accepting inbound multicasts for the fullest IPv6 experience.
When your local ISP still does not offer native IPv6 addressing and traffic, a good way to start using IPv6 is to get a free 6to4-tunnel from Hurricane Electric .