EGPWS - Terrain Versus Obstacle

[SR71]

Can someone enlighten me as to whether the difference between an aural TERRAIN, TERRAIN, PULL UP warning and an OBSTACLE, OBSTACLE, PULL UP warning merely relates to the nature of the object the system perceives as responsible for the impending collision?

i.e., if it was a mountain, the warning would be of the first kind, but if it was a mast or tower, it'd be the second?

[alf5071h]

SR71, the TERRAIN and OBSTACLE warnings are independent and relate to the nature of the threat. Thus, whichever item is sensed first, it provides the caution and alerting messages. i.e. CAUTION TERRAIN (amber) and TERRAIN TERRAIN PULL UP (red) for terrain, or CAUTION OBSTACLE (amber) or OBSTACLE OBSTACLE PULL UP (red) for obstacles. I assume that an OBSTACLE PULL UP could follow a CAUTION TERRAIN it the aircraft’s manoeuvre and relative geometry to the obstacle were appropriate.
More details are available in the EGPWS pilot guides, Mk V & VII. Other pilot guides are available in this link.

The above only applies to those systems that have the obstacle database and alerting function activated. At a recent operator’s conference, Honeywell reported that they supply all of the required changes free of charge, but that the major airframe manufacturers are charging for the ‘Mod’ (changes to the books?). Airbus reports a significant reduction in their charges to aid safety.

Rumour has it that the first large aircraft has been saved by an ‘obstacle’ callout. The free downloadable EGPWS obstacle database is here. This link also give details of the obstacles in the database, the world wide terrain coverage, all airports, and all runways that the system recognises; very impressive.
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Unless specifically authorized everything else is forbidden.

[Blacksheep]

At a recent operator’s conference, Honeywell reported that they supply all of the required changes free of charge, but that the major airframe manufacturers are charging for the ‘Mod’ (changes to the books?). Airbus reports a significant reduction in their charges to aid safety.

Equipment vendors such as Honeywell, Thales or Rockwell Collins often do provide system support data free-of-charge, but the problem is airframe manufacturers then charge a substantial fee for including this data into the aircraft manuals. In the past, new systems would be installed using airframe manufacturers' service bulletins that included aircraft MM revisions. Since the US Congress acted outside FARs to mandate TCAS directly, it became increasingly common for aircraft manufacturers to refuse to issue an SB. Operators must then negotiate with the equipment manufacturer for a Supplementary Type Certificate to cover installation into the aircraft. In this cae, Technical Data supplied as approved drawings must be re-published as a support manual.

It is possible for operators to publish the data themselves, as supplementary manuals to the AMM, but this is far from ideal. Especially in an environment where most technical manuals are published in digital format and it is necessary to provide cross-reference links.

It would be going too far to suggest that manufaqcturers do not care about safety, but there is no doubt that mandatory actions have become a lucrative source of revenue from a captive market. The Pork Barrel rolls on, long live democracy.

[Engineer]

“Obstacles” is a feature utilizing an obstacle database for
obstacle conflict alerting and display. EGPWS caution and
warning visual and audio alerts are provided when a conflict
is detected. Additionally, when TAD is enabled, Obstacles are
graphically displayed similar to terrain. This feature is an
option, enabled by program pins during installation.