Weather: thunderstorms, turbulence, icing, wind shear, cross/tailwind, very low/high temperatures.
ATC: traffic congestion, TCAS RA/TA, ATC command, ATC error, ATC language difficulty, ATC non-standard phraseology, ATC runway change, ATIS communication, units of measurement (QFE/meters).
Airport: contaminated/short runway; contaminated taxiway, lack of/confusing/faded signage/markings, birds, aids U/S, complex surface navigation procedures, airport constructions.
Terrain: High ground, slope, lack of references, "black hole".
Other: similar call-signs.
Operational pressure: delays, late arrivals, equipment changes.
Aircraft: aircraft malfunction, automation event/anomaly, MEL/CDL.
Cabin: flight attendant error, cabin event distraction, interruption, cabin door security.
Maintenance: maintenance event/error.
Ground: ground handling event, de-icing, ground crew error.
Dispatch: dispatch paperwork event/error.
Documentation: manual error, chart error.
Other: crew scheduling event
Manual handling/flight controls: vertical/lateral and/or speed deviations, incorrect flaps/speedbrakes, thrust reverser or power settings.
Automation: incorrect altitude, speed, heading, autothrottle settings, incorrect mode executed, or incorrect entries.
Systems/radio/instruments: incorrect packs, incorrect anti-icing, incorrect altimeter, incorrect fuel switches settings, incorrect speed bug, incorrect radio frequency dialled.
Ground navigation: attempting to turn down wrong taxiway/runway, taxi too fast, failure to hold short, missed taxiway/runway.