G'day,
There is a lot of overlap in the definition of an external threat and an environmental threat. External threats does seem to be the more usual term but CAAP 5-59 mentions the word "environmental" and gives specific examples and if they turned up in the exam I'd think CASA would call those examples environmental threats. Here's what can be extracted from the CAAP and other sources.
EXTERNAL THREATS: adverse weather; weight and balance; density altitude; runway length; other traffic; high terrain or obstacles; or the condition of the aircraft.
ENVIRONMENTAL THREATS: Weather (turbulence, ice, wind); Aerodromes (congestion, complex surface navigation, poor signage/markings) ; ATC (non-standard phraseology, complex clearances, poor English language); and Terrain (mountains, valleys, built up areas)
As you can see there's a lot of overlap. Environmental threats seem to relate more directly to the immediate environment in which the aircraft operates whereas external threats is a more generalised. I just checked the CAAP again and they describe an environmental threat as:
"Environmental threats occur outside the control of the aircraft operator due to the environment in which the
operations take place and have to be managed by the pilot
in the available time. " (emphasis is mine)
This has a sense of immediacy about it. Bad weather is an external threat but turbulence, icing, wind would be environmental threats while the pilot is dealing with them. An unfamiliar aerodrome is an external threat but a confusing collection of taxiway signs while you are taxiing at that aerodrome would qualify as an environmental threat.
Organisational and internal threats on the other hand are different.
Internal threats are threats the flight crew bring with them to the cockpit environment. I like to think of it as anything that is going on inside the pilot's skin either physiologically, psychologically or associated with their skill set. So, a hangover is an internal threat, lack of recency in an internal threat, depression is an internal threat.
An organisational threat on the other hand is a threat associated with the actions or inactions of the operator responsible for flight operations. The classic examples are in CAAP 5-59 and include things like issuing out of date charts to pilots, tight schedules for flight sectors etc. Organisational threats are often also latent meaning they are like an accident waiting to happen. Tight scheduling for example is an organisational threat (it has to do with how flight operations are organised) but it is also a latent threat since tight scheduling may one day lead to a pilot rushing a checklist and committing an error.
My recommendation is read CAAP 5-59 Sections 13 and 14 very thoroughly
and make sure you have it with you in the exam (CAAP 5-59 is not part of the allowed materials in any CASA exam
). Once you understand the concepts and can apply them it might help to use a highlighter to mark the specific examples in those sections so you can spot them easily while revising. Specific examples from the CAAP are the ones that crop up often in the exam.
Good luck!
Cheers,
Rich