Source: Elines 

Recently there has been some confusion about the usage of cabin jumpseats on weight restricted flights. Section 3.A of our JCBA was implemented October 4, 2016. When a cabin jumpseat is available, but the aircraft is weight restricted, cabin jumpseat authority will not be denied to any Flight Attendant, regardless of pre-merger affiliation. The number of Flight Attendants utilizing cabin jumpseats on weight restricted flights is limited to the number of available cabin jumpseats, and should never be denied due to the flight being weight restricted, provided all listing and check in protocols have been met.

Follow proper protocol when listing for a flight. Flight Attendants must check in for the cabin jumpseat no later than 30 minutes prior to scheduled departure. Flight Attendants who have met the 30-minute check-in shall be awarded available cabin jumpseats. In instances where self-service electronic means are not available, Flight Attendants shall have the ability to list and check in with Customer Service Representatives (CSR) no later than scheduled departure. 

For additional information please see your Local Council Representatives.