The CAA's 'Aviation Trends' report revealed that only 55 per cent of Blue Islands' flights were on time between April and June this year.
This analysis covered the top 20 largest airlines in the UK, with a flight considered 'on-time' if it arrives or departs within 15 minutes of its scheduled time.
Blue Islands stated that its poor punctuality was due to operational issues, industry-wide supply chain problems, and the late delivery of aircraft.
The airline reported a significant improvement in August, with 74 per cent of its flights arriving on time, while Scottish regional airline Loganair was found to be the most reliable overall.