The system in an airliner is a bit more complex, some have 3 buttons (depends on aircraft type and configuration) for suppressing the alarm:

1 GLIDE SLOPE -if the approach is deliberately performed below G/S
2 GPWS flap override or OFF -when approach is performed with other than normal flaps configuration (reduced flaps landing) or landing gear problems
3 Terrain OFF -switch for system malfunctions (eg invalid position or disagreement), or turning off the enhanced mode for ditching, forced landing.. (kills the TAD and TCF functions -other basic GPWS modes remain active)

During night or IMC conditions, apply the escape procedure immediately. Do not delay reaction for diagnosis.

ok
 

So for the sake of clarity, the terrain warning system is NEVER turned off for normal operations...

I think the request raised here is not relevant to normal operation. The request is related to operating the airplane at non-standard airports surrounded by high terrain.

HONEYWELL: Pressing the TERRAIN INHIBIT switch inhibits TAD and TCF alerting and display, including Obstacles and Peaks when enabled. This is typically used when operating at an airport not in the terrain database. Selection of Terrain Inhibit does not cause the Terrain Inoperative or unavailable annunciation unless the aircraft is wired for this to occur. Terrain Inhibit requires manual deactivation.

BENDIX/KING: TERRAIN INHIBIT SWITCH: The purpose of Terrain Inhibit is to allow aircraft to operate without nuisance or unwanted warnings at airports that are not in the system database. Examples might be private airports or those with runways shorter than 2000 feet. Additionally, there may be some "VFR-only" airports where unique terrain features are in close proximity to the runway, and Terrain Inhibit may be used when operating in good VFR conditions. Terrain Inhibit should be NOT engaged for normal operations.
Note that the Terrain Icon shows a yellow exclamation point and the TAWS status shows TERR INHBT to indicate that warnings are inhibited.

Further more; HONEYWELL offers the following discretes:
Control discretes control EGPWS functions. These include EGPWS Test, Glideslope Cancel, Glideslope Inhibit or Glideslope Backcourse, Terrain (display) select, Terrain Inhibit, Flap Over-ride, Audio Inhibit, Altitude Callout Enable, Steep Approach Enable, and ILS Tuned discretes.

So it really comes down to the type of operations. If one often operates to airpots surrounded by high terrain; deactivation of the audio warnings will reduce distraction and I do understand the request. On the other hand, I completely understand the risks involved if that TERRAIN INHIBIT feature is misused.

And why did they not react? Why do some crews, even today, as shown by FDAP, not automatically react in night VMC or IMC as required?

My point was not GPWS as a distraction in the immediate case of Flying Tigers, but GPWS was fairly new and at the time and crews didn't trust it so they were conditioned to ignore alerts. In fact the crew canceled several of the alerts prior to impact. The GPWS was suppose to be the last chance to break the error chain and it did not. The design of a human interface requires deeper attention. Simply saying ignore alerts in VMC and don't in IMC is too simplistic for something warranting fuller understanding, especially when these technologies are just recently available to a wider aviation audience.

I believe a TERRAIN INHIBIT feature in most transport category aircraft, and mentioned by supik, is an important feature to have readily available with any GPWS/TAWS technology, and not deep in an interface menu.

We're not talking about airliners. We're talking about sport EAB airplanes under Part 91. Aside from the RVs I own an Aviat Husky and am partners in an new turbine SEAT fire bomber. You want to go insane hook up terrain warnings to unswitched audio. Same goes for traffic when flying formation. I see no sense in STC instructions assuming everybody is an airliner with full time aural anunciators. I say the alerting systems should follow a customized sterile cockpit rule based on the installed airplanes' mission profile. Every fire bomber I know either doesn't hook up the unswitched audio alerting or hooks it up to a switched selector on the audio panel, like com3 or ADF. STC instructions be danged.

There is an old joke where a twin landed gear up and somebody asked the seasoned pilot how it could have happened, and he responded that he was all dialed on the approach until all those flashing lights and bells made him loose his concentration. Not all pilots have the same makeup and some are more visual, some more auditory and others might need a poke in the ribs.

If someone flies their RV extensively in IMC under IFR rules then it would be advisable to have alerts available, but still at the option of the pilot. The other 90% of RV flying is VFR where unswitched audio alerts are fatiguing and can even freak out passengers on the intercom.

Jim

Jim understands what I'm saying...I spent 4 years flighting fire and the STC of tanking a 146...when the tank is armed it killed all aural alerts...gear, TCAS, GPWS, etc. The purpose was to prevent distractions but also prevent conditioning of the crew to ignoring these alerts.

I don't think anyone here is disagreeing that there should be an option of disabling alerts under certain flight conditions, as already exists on most if not all systems.

And the Flying Tiger accident is still not an example of GPWS causing or contributing to an accident. I'm unaware of any accident in any database which lists the presence of a GPWS alerting system as a contributing factor. Poor training yes. Lack of cockpit discipline yes. But not the simple fact that it was there.

My request in
 

My request in the G3X Wish List from previous year. Post nr246:

Quote:

Originally Posted by supik (Post 1298660) Optional remote TERRAIN MUTE Button/Switch to quickly mute nuisance Terrain Warnings when flying VMC in mountainous area or approach surrounded by terrain in VMC. Mute sound warning only, visual cues shall remain visible on map and synth vision. Normally, (if installed) this switch should be guarded.

Hello,

Just a reminder that there are already very quick and efficient ways to disable traffic and/or terrain alerts on a G3X Touch system if that is something you need to do on a particular flight.

Select the terrain or traffic page, press the Menu button, and enable/disable alerts for that type.

This is all explained in the Pilot Guide.

One the next power cycle, these alerts are automatically re-enabled at power-up.

Thanks,
Steve

The one I would like is a ?Trim-In-Motion? aural alert (I?m electric only trim.

I maybe can cheat a way around this by configuring Yellow+Alert a bunch of times in 1% ranges every 10%

+5 to -5 - T/O trim green
15%-16% Alert
25%-26% Alert
35-36 Alert
And so on for plus and minus.

The idea is I get a quick tone and CAS message of trim movement

Might work. Might not.