Monitoring climb profile during an instrument departure (SID) - merged

what_next wrote:

Strictly speaking, with certified TAWS, warnings are just warnings (“CAUTION TERRAIN!”). One does not have to react to those other than wake up and have a look at the screen which will automatically display terrain data, even it it had been deselected. But the command “PULL UP!” must be followed instantly. Opinions (and SOPs of different companies) vary if that is also the case when one has visual contact.

As I am still interested in active (i.e. aural) terrain avoidance feature, I have been a bit more into difference between Synthetic Vision (SVT) and TAWS.
SVT includes some aural alerts, but the algorithm is more limited, and won’t take into consideration some significant dangerous conditions. Thus, in the end, you will rely on your interpretation of the 3D-view, and not on an instruction to follow.
That’s why, I tend (without experience :-) to consider the TAWS more as an active safety feature, and SVT as an awareness safety feature. Many users have said that they felt more confident during instrument approaches with it, but being more confident doesn’t mean you’re safer… I guess both increase safety, somehow, but even if less fancy or visible, TAWS is the one you really want to watch above your shoulder.

Here are the different terrain avoidance functions / algorithm, provided by the G1000 (this is from the handbook):

• Forward Looking Terrain Avoidance (FLTA) – which looks ahead of the aircraft along and below the aircraft’s lateral and vertical flight path and provides alerts if a potential Controlled Flight into Terrain (CFIT) threat exists
• Premature Descent Alert (PDA) – uses the aircraft’s current position and flight path information as determined from a suitable navigation source
  and airport database to determine if the aircraft is significantly below the normal approach path for the destination runway
• Excessive Descent Rate Alert (EDR) – when the aircraft is determined to be closing (descending) upon terrain at an excessive speed
• Negative Climb Rate Alert (NCR) – when the system detects the aircraft is losing altitude (closing upon terrain) after takeoff
• “Five-Hundred” Aural Alert – when the aircraft descends within 500 feet of the terrain or nearest runway elevation

SVT only provides the first function / algorithm: FLTA. Aural alerts are limited to: “Obstacle”, “Terrain”, with preceding “warning” or “caution”.
TAWS, with more functions / algorithms, adds more vocabulary: “Pull up”, “Sink rate”, “Don’t sink”, “Too low” and “Five hundreds”. Each is triggered in precise condition, and provides an order to follow.

That was my saturday penny