You might ask your cabin steward for a mattress pad or an extra duvet to provide a softer support for the back. As Jim C. has said - the issue is space and an air mattress can make things feel very cramped! If worse comes to worse consider a campers mattress pad or two - they roll up easily and won't take too much packing space!!! Place it under the mattress on the sofa bed forthe best effect - I've done it on a sofa bed at a friends house and it worked quite well!!