No. Personal barometers containing mercury and must not be taken on a plane. Aneroid barometers do not contain mercury and are allowed
Government employees may travel with specialised equipment that contain hazardous substances, including barometers containing mercury. If this applies to you please contact your airline before you travel as their approval will be required and in most cases the pilot is required to be informed.
Mercury is a poison and if taken on board a plane present as a significant risk to passengers and crew.
You will be asked to relinquish all dangerous or prohibited items found in your carry-on luggage. If you refuse:
AvSec X-ray bags going onto aircraft to ensure there is nothing dangerous in them.
If you want to retrieve an item that has been removed, please contact your airline as soon as possible. The airline will dispose of items within three to seven days, so the sooner you make contact, the better your chance of having the items returned to you. For more information, see: