Question: who is responsible for determining if an aircraft is airworthy
[{'answer': 'a national aviation authority'}, {'provenance': [{'wikipedia_id': '8530637', 'title': 'Airworthiness', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 282, 'bleu_score': 0.788267242172898, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15849143199462441260}, 'section': 'Section::::Abstract.'}]}]