1. Delayed departure
1.1. check-in
1.1.1. poor queue management
1.1.1.1. limited staff
1.1.1.1.1. hire more staff
1.1.1.2. unskilled staff
1.1.1.2.1. training required
1.1.2. systems not working
1.1.2.1. temporary
1.1.2.1.1. add backup systems
1.1.2.2. permanent
1.1.2.2.1. upgrade legacy systems
1.2. security clearance
1.2.1. limited number of gates
1.2.2. unskilled or slow staff
1.2.2.1. train staff
1.2.3. limited staff
1.2.3.1. hire more staff
1.2.4. faulty equipment
1.2.4.1. upgrade technology
1.3. boarding
1.3.1. crew arrived late
1.3.2. passengers arrived late
1.3.2.1. connecting flight passengers
1.3.2.1.1. previous flight got delayed
1.3.2.1.2. previous flight was on time
1.3.2.2. direct flight passengers
1.3.2.2.1. implement strict boarding time procedures
1.3.3. flight arrived late
1.4. aircraft preparation
1.4.1. fueling
1.4.1.1. Improve co-ordination between teams
1.4.2. catering
1.4.3. cargo loading
1.4.4. safety check
1.4.5. cleaning
1.5. delayed takeoff
1.5.1. Bad weather
1.5.2. Runway issues
1.5.3. technical glitches
2. On time departure but delayed arrival
2.1. Bad weather
2.2. runway issues
2.2.1. congested runway
2.2.1.1. improve scheduling
2.2.2. technical fault at runway
2.2.2.1. ensure proper maintenance
2.3. Delay by ATC
2.4. Medical emergencies on flight
2.4.1. proper first aid facilities
2.5. Security issues - hijacking, terrorism
2.5.1. security needs to be improved