Are you allowed to use your DSI on a Airplane?

Yes you can use your ds on an airplane but some have no wifi so no internet

Use of the Nintendo DSi may be allowed in planes when wireless data transfer is not used or is switched off. An active wireless communication is shown by rapid flashing of the usage light on the Nintendo DSi.

Please always follow the specific security guidelines of the airline to avoid any disturbance of the plane's technology on board.