As a general rule, travel neck pillows don't offer any support, alignment, or comfort and are not recommended for travel. Even though neck pillows have existed for almost 100 years, there is no evidence, either personal or scientific, to suggest that these travel neck pillows have any efficacy.
If you know you're prone to aviation headaches, take a non-steroidal anti-inflammatory agent (i.e. ibuprofen) one to two hours before takeoff to get ahead of any inflammation or pain.
Normally airlines allow people to take their own pillows on board as it's useful to have when sleeping and such. However this is just something they allow rather than being a right. So the airline might not allow it on board and in case of a “rather large” size they might make you send it to the cargo haul.
Once you board a plane, you may be in for quite a long flight, depending on your destination. To make yourself comfortable for the next however many hours, you might want to make use of some of the amenities being offered to you, including the complimentary pillows and blankets that are often left on your seat.
The best neck pillows for travel are made from soft, breathable material that won't irritate your skin. Airplanes can get stuffy—especially if you're in the middle seat—so having a pillow made from a light, airy material will help keep you cool.
For the unlucky middle seat, he said to, “use a neck pillow, and lean slightly forward with arms folded or rest your head on the tray table with a cushion.” Finally, for the aisle seat, he suggests leaning slightly to the side using a neck pillow, but just make sure to not block the aisle way.