PAXboy. .. .Pan is a code word that is used t indicate a state of urgency as opposed to mayday which is a distress situation. If an acft capt used either in his/her transmissions then it indicates the degree of seriousness that the problem he/she is in.. .. .A couple of simple examples, an engine fire would initially warrant a mayday which could be downgraded to a Pan once the fire had been extinguished. AN engine failure in a single engined acft would be a Mayday untilthe acft had landed, where as an engine failure in a 4 engine would be a pan.. .. .Thes are only general comments and all situations are open to personnel interpretaions and experience. I did hear a rumour once that a 737 landed single engine without a word to ATC, but the controllers did notice a change in speed of the acft as it was enroute. I also educated a FO one day who was reluctant to relate a problem we were having to ATC because he thought it was embarrasing. Its not our fault when things go wrong mechanically with the acft but the way we handle it afterwards can affect the outcome.. .. .Hope I haven't bored you to tears.