PAN-PAN (urgency) is more common in other countries. In the US, pilots typically "declare an emergency" which can be anything from a engine caution message, to

PAN-PAN (urgency) is more common in other countries. In the US, pilots typically "declare an emergency" which can be anything from a engine caution message, to a critical emergency, which would justify a MAYDAY call. Sometimes, pilots will upgrade a PAN-PAN to a MAYDAY if their situation gets worse. One reason for US pilots to only declare an emergency, and not "urgency" is when a pilot requests priority, FAA procedures sometime require Air Traffic Controllers to treat a priority or urgency as an emergency, even if the pilot does not expressly declare the emergency. Almost all airliners require 2 pilots. Unless they have a relief Captain, or fully qualified jumpseat pilot, they have to declare PAN-PAN (urgency) or emergency, when flown by a single rated pilot. The chief flight attendant (pursor) may assist in the cockpit, and frequently does sit in the cockpit seat, when either pilot uses the bathroom.