Some airlines are refusing to carry Mac Book Pro 15" laptops if purchased between September 2015 & February 2017. According to Apple the batteries can overheat with the potential to ignite. Some airlines allow them to be carried in the hold luggage only, others in hand luggage only, but they must remain switched off during the flight. Others have banned them completely. If you are travelling with a Mac Book Pro purchased in this time frame, it would be wise to check the regulations of the airline you are travelling with prior to your travel date. While Apple is replacing faulty batteries, Airlines require proof of new battery.