Getting a < 75 Watt charger for a macbook pro due to flight constraints My MacBook Pro with Retina display (Mid 2012) charger has a rating of 85 Watts. 

I want to use it on a flight from Sydney to Los Angeles. (24 hours). (Airbus A380-800). 

You can plug in an AC adapter - but they have the following rule:


  The PC power is configured to provide a maximum of output of 75 watts. If the limit is exceeded by a user, which is possible on new version PCs the power to the user will be interrupted and can only be reset on the ground.


This means if I plug in my charger - I'll lock out my power supply for the remainder of the 24 hour flight. 

Can I get a lower wattage power adapter for my MacBook Pro?
Apple sells a 60W MagSafe2 Power Adapter for US$79.00 for the MacBook Pro with 13-inch Retina display. They also sell a 60W MagSafe Power Adapter.