kijangnim “Peaks mode is more an Enroute function, whereas Obstacle is more a TMA function”
Yes, or alternatively:
Peaks mode is threat avoidance (planning) and obstacle mode is error recovery (as for terrain modes)
EGPWS may likened to a threat and error detector, and an error avoidance/recovery instrument, thus from either view there are good arguments for displaying terrain (peaks) when planning (briefing) and flying all departures and arrivals.
PEI_3721 Re non standard atmosphere correction (#8). As I understand, EGPWS uses geometric altitude within the warning logic to provide ‘corrected’ warnings, maintaining the integrity of the ‘error detector/recovery’ system. However, EGPWS does not correct any of the normal altimeters etc; this is still a crew responsibility. This is particularly important with FMS/VNAV approaches, for which the majority are based on pressure altitude.
EGPWS may provide a display of geometric altitude (“true altitude”) depending on certification rules/installations. Also some systems may have an altimeter comparator alert when pressure and geometric differ by a certain value – another, much needed error detector function well before any terrain alert/warning.