Single pilot aircraft flown by two crew?

[Johnno1981]

Hi

I have a question about flying as captain on a single pilot aircraft flown by two crew, for example a Twotter or Kingair. Do you need to have an Atpl to do this, what are the licence requirements under JAR and do they differ between ICAO states?

I'm asking because I am looking into the possibility of getting a job as co-pilot on an aircraft like the Twotter or Kingair and was wandering what the requirements for upgrade to Captain would be?

Thanks