Aviation: Summer Delays

Summer is the busiest travel season of the year – and also one of the most frustrating for airline passengers. Flight delays can feel unpredictable and endless, but they’re not random. We break down the most common reasons flights get delayed during the summer months, from weather patterns and air traffic congestion to staffing shortages and outdated infrastructure.

What the Data Really Says

• ✅ Air traffic flow management (ATFM) delays — including staffing, capacity, and weather — represented about 20–25% of all delays.
• ⚠️ Reactionary delays (knock-on effects from earlier flights) remain the single largest cause of delays.
• ✈️ Airline-related causes — such as ground handling, crew shortages, late aircraft rotation — are substantial and often underreported in public discourse.

Download our full Factsheet here.