This is where having the terrain database and the G1000+syn vis etc helps. Not only will you get an audio warning but you will also be able to see the terrain and a possible vector to get the most space you can on both map and PFD. On the G1000 map page it will show yellow and red flashing areas that are at risk from or above your altitiude.
You can also silence the alert with a button rather than pulling the CB which is not a good thing to have to do as it is easy to forget to reset it.
Interesting article on GPWS and CFIT accidents: Celebrating TAWS ‘Saves’: But lessons still to be learnt
While I have no knowledge of the equipment in this aircraft, it is worth considering that the twin Comanche that went down in Nice two years ago was well equipped (described a a 'glass cockpit' with additionally a yoke mounted GPS with two GPS having Terrain Alerting). It seems that either the devices are not plumbed in to give sufficient warning (mine doesn't link to the audio so relies on catching your eye by flicking the display to the terrain page) or pilots are not responding effectively.
In the following video I do an approach through the cloud desk at Courchevel after having circled the airfield to check that the runway was clear to land (tower was closed that day). Due to a thin cloud layer I did an alternative downwind/base approach and at 1 minute 45 seconds you see my PFD turning completely red, which is the synthetic vision in the Cirrus. Too bad I did not have a recording of what I would hear at that time in my ears, but that would be something like "pull up! pull up! terrain! terrain!" and would be very hard to miss. The synthetic vision feature just shows you the mountains around you and it would be hard to miss, but of course it is not something to rely on for basic navigation.
[Fixed - see my post below - Peter]
This thread prompted me to read the manual for the Honeywell KMH-880 EGPWS system in my aircraft. Very interesting. Happy to answer any specific questions on how they work or in what circumstances they activate.
For example: It blends GPS altitude with uncorrected barometric altitude to get a reference altitude for comparison to its database. That altitude can also take a temperature input. It uses a look ahead function to see obstacles or terrain 1 minute from the aircraft when it gives a caution. At 30 seconds it gives a warning. Also when within 5nm of a known runway you get a Runway field clearance floor. Penetration of this floor also gives a warning. It is 300ft between 5 and 2.5 miles and then descends to 0 at 1 mile.
You also get a sink rate or pull up warning. At 1000ft the sink rate warning comes if ROD is about 3000ft/min and if it is 5000fpm it will be pull up pull up. At 500ft they both activate at about 1800ft/min.
You also get a don't sink warning after takeoff if you have a rate of descent which adjusts with altitude above field.
You can get a check altitude warning which can alert to a blocked pitot.
You also get the well known 500 to go alert when within 5nm of a known runway.
Jason,
This thread prompted me to read the manual for the Honeywell KMH-880 EGPWS system in my aircraft.
I assume your TAWS-B was installed at the Factory as one of the Meridian listed options (Piper Meridian Specs 2013).
Am I correct in assuming that one can order a KMH-880 EGPWS ($12,000 ?) only as an add-on to the KTA-870 (Traffic Advisory System) (priced at $48,000 in 2013)?
Or, is the "$12,000" TWAS-B option listed in these specs simply the standard Garmin (for G1000) terrain awareness functionality ungraded to meet TWAS Class-B system requirements (remote warning annunciators/audio interface)?
I don't know but I have never seen one seperate from the traffic system. People always seem to have both.
From here
yappmeister wrote:
Plus if you have the terrain alerting check it can be done over the water
That’s something (TAWS) I hadn’t even thought of. Having checked the pricing I think I will continue to not think of it!
TAWS-B should be enough :-)
PetitCessnaVoyageur wrote:
TAWS-B should be enough
OK – I’ve now learned the difference between TAWS-A and TAWS-B, but it’s still beyond my budget:
