Dear Irish Steve,
Interesting question. Alot of students have done their dissertations on the subject and variants of this subject. I have a lot of files on my computer but have to dig them out. Here are some links to some good reading on the subject.
Regarding a study done just on multicultural and multilingual flight crews I will try to find the exact study for you.
A lot of incidents and accidents have happened with the lack of language proficiency and difference in culture as a link in the chain. The Helios accident was reported of the German captain and Cypriot F/O having difficulty understanding each others' types of English which, supposedly, led to the Captain "ignoring" the F/O. This is what the journalists said. We know that due to hypoxia it could be another story, not necessarily linguistic. However, his German English and the F/O's Cypriot English could have played a role in not solving the problem.
As My Name's Turkish writes below, this is also a cultural problem in some cases. Learning language and culture are two different paths...
Here are some links, as I find more I'll pass them on.
Best,
PE
http://www.highbeam.com/library/docF...D=1G1:20873101
http://homepage.psy.utexas.edu/homep.../HelmreichLAB/ Sexton, B.J., & Helmreich, R.L. (2003). Using language in the cockpit: Relationships with workload and performance. In R. Dietrich (Ed.), Communication in High Risk Environments (pp. 57-73). Berlin: Humboldt Universitat zu Berlin.
http://www.hf.faa.gov/docs/508/docs/...uageYr1rpt.pdf