It depends very much on the airline. Ask the crew nicely, keep it brief and quiet, and make sure it's outside meal service and sleep times. European airlines are fiercely protective of the cabin separation, whilst on some gulf and asian carriers it can seem like piccadilly circus at rush hour.

In 2026, you generally cannot visit someone in Business Class if you are traveling in Economy or Premium Economy. Airlines maintain a strict "cabin separation" policy to protect the privacy and premium experience of passengers who have paid significantly more for their tickets. Flight attendants use the "curtain" as a hard boundary; allowing passengers from the back to congregate in the aisles or galleys of the premium cabin creates security risks and disrupts the quiet atmosphere. Even if you are traveling with a family member who is "up front," the crew will usually ask the Business Class passenger to move back to the Economy section if you wish to speak or share a meal. A high-value "pro-tip" for 2026 is that some airlines like Emirates or Qatar Airways may allow a brief "social visit" if the Business Class passenger has a private suite and you are discreet, but you will never be permitted to sit in an empty premium seat or use the Business Class lavatories, as "cabin poaching" is a major point of friction for modern flight crews.