From ICAO language proficiency rating scale, Operational Level 4:
Pronunciation:
Pronunciation and stress influenced by the first language.
Structure:
Basic grammatical structures and sentence patterns used creatively and are usually well controlled.
Vocabulary:
Vocabulary range and accuracy sufficient to communicate effectively on common, concrete, and work related topics.
Fluency:
Produce stretches of language at an appropriate tempo.
Comprehension:
Comprehension mostly accurate on common, concrete, and work related topics
Interactions:
Responses immediate, appropriate, and informative. Initiate and maintain exchanges. Deal with apparent misunderstandings by checking, confirming, or clarifying.