Q 1: Is it permissible
for a wife to travel alone by plane for three hours not accompanied by a Mahram (spouse or permanently unmarriageable relative)?
It should be noted that there are no female doctors in the country where her husband works so they may help her with delivery. The main reason for her travel is to deliver at the hands of female doctors in the country of her family.
In such a case, the husband or one of her Mahrams has to travel with her. (Part No. 17; Page No. 309) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.