Q. Dear Rabbi. Can someone traveling in a plane and sitting next to two non-Jews can he drink beer together with them?

A. Based on Talmud Avoda Zarah (31b), Shulchan Aruch (Y.D. 114) rules that a Jew should not drink beer together with Gentiles, to avoid promoting assimilation and intermarriage.

However, Poskim permit when the drinking together is only by coincidence (Derech Aray) and not as an established party or similar (See Chochmas Adam 66: 14).
They also are lenient when it would also avoid enmity and create ill feelings. (See Psokim Uteshuvos 114).
Horav Shlomo Miller’s Shlit’a opinion is similar.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller, Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit’a