Setting the 0x200 flag in AdventureSettingsPacket should enable client-sided flight controls, and unsetting it should disable them.
The client still sends this flag when it enables flight controls on its side, but the server cannot switch the client's controls on and off using this flag. This used to work before ~1.0.4.

This is observable in vanilla by joining a multiplayer creative world, enabling flight controls, quitting and rejoining. On rejoin the client will spawn in its old mid-air position and then fall to the ground, and flight controls will not be enabled.

• Expected behaviour
  Setting this flag to 1 should enable flight controls, and setting it to 0 should disable them.

• Actual behaviour
  Nothing happens.

Tested on an LG G5 and LG G Flex 2 with 1.0.6.0.