EGPWS terrain display
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EGPWS terrain display
What is the general rule regarding the displaying of terrain/peaks mode on the MFD? A common practice seems to be that operators with egpws have the terrain on below MSA and if the weather radar is required then the PF has the radar on their MFD and the PNF has terrain displayed. Any thoughts as even different fleets within an airline have slightly different operating philosophies on the displaying of terrain.
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Personally, I use terrain feature only if it is a factor, eg take off/landing at LHR or JFK it is not a factor, therefore 'wx' provides more useful information of both sides of he flight desc. If it is a factor on climb or descent (or even in the cruise) then I like to see it displayed on one side, probably better on the pilot not flying's side, with PF displaying 'wx'.
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We have some airplanes in the fleet which have independent radar displays,and some which put it on the EHSI. When it's on the EHSI we can see either radar or terrain, but both. When we have a separate screen, we can see both. Some never fly with the terrain display. I find it useful, and keep it up when weather isn't the priority. The company is silent on the matter, so far as I know.
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We normally set terrrain on the PNF side and WX on the PF side but we are free to set whatever is the most sensible for the day.
Terrain should be shown on at least one display at all times after the descent briefing, and for all departures.
A significant point about CFIT is that you don’t know when terrain is significant; also, many CFIT accidents occur on relatively flat terrain during the final approach.
Furthermore, the terrain display can show obstacles, not necessarily associated with terrain.
EGPWS is a threat and error management device; the terrain display shows the threat, the alerts and warnings indicate an error which should be rectified immediately.
Ref: FSF ALAR Tool Kit report ‘Killers in Aviation’.
Incidents, for inf: Celebrating TAWS ‘Saves’: But lessons still to be learnt.
System upgrades, obstacles etc: Indispensable Upgrades.
A significant point about CFIT is that you don’t know when terrain is significant; also, many CFIT accidents occur on relatively flat terrain during the final approach.
Furthermore, the terrain display can show obstacles, not necessarily associated with terrain.
EGPWS is a threat and error management device; the terrain display shows the threat, the alerts and warnings indicate an error which should be rectified immediately.
Ref: FSF ALAR Tool Kit report ‘Killers in Aviation’.
“Sixty-seven percent of CFIT occurrences were in hilly or mountainous-terrain environments, and 29 percent were in areas of flat terrain. This suggests that significant terrain features are not necessarily a prerequisite for CFIT.”
“(c) Procedural errors, situational awareness errors and tactical decision errors were the dominant crew-error types, whereas those related to communication appear to be less of a problem. In the special case of landing (approach) phase accidents, virtually all the accidents involved a situational awareness error;
(d) The landing (descent) phase and landing (approach) phase accidents together accounted for almost 70 percent of all accidents, whereas the en route phase accounted for about 20 percent. Where data were known, 93 percent of the en route accidents were attributable to air taxi and regional operators;
(e) Major and air taxi operators suffered their greatest losses in the landing (approach) phase, and the regional operators encountered the largest percentage of accidents in the en route phase;
(f) Almost 60 percent of the 66 landing (approach) phase accidents where data were known involved aircraft flying nonprecision approaches. Twenty-five percent (17 cases) of all approaches were of the VOR/DIVIE type;
(g) Almost all landing (approach) phase accidents (90 percent) occurred within a radius of approximately 15 NM (17.25 statute miles/27.76 kilometers) from the runway threshold;
(h) In almost 40 percent of the landing (descent) phase and landing (approach) phase accidents, significant terrain features were absent in the vicinity of the airfield. This indicates that CFIT accidents do occur in areas without high terrain;
(i) In 30 accidents (one-fifth of the total sample), inadvertent VMC flight into IMC was a factor. Most of these accidents occurred in single-pilot operation flights, involving regional and air taxi operators. Seventeen of the 30 VJVIC-into-IMC accidents (56.7 percent) occurred in the en route phase.”
“(c) Procedural errors, situational awareness errors and tactical decision errors were the dominant crew-error types, whereas those related to communication appear to be less of a problem. In the special case of landing (approach) phase accidents, virtually all the accidents involved a situational awareness error;
(d) The landing (descent) phase and landing (approach) phase accidents together accounted for almost 70 percent of all accidents, whereas the en route phase accounted for about 20 percent. Where data were known, 93 percent of the en route accidents were attributable to air taxi and regional operators;
(e) Major and air taxi operators suffered their greatest losses in the landing (approach) phase, and the regional operators encountered the largest percentage of accidents in the en route phase;
(f) Almost 60 percent of the 66 landing (approach) phase accidents where data were known involved aircraft flying nonprecision approaches. Twenty-five percent (17 cases) of all approaches were of the VOR/DIVIE type;
(g) Almost all landing (approach) phase accidents (90 percent) occurred within a radius of approximately 15 NM (17.25 statute miles/27.76 kilometers) from the runway threshold;
(h) In almost 40 percent of the landing (descent) phase and landing (approach) phase accidents, significant terrain features were absent in the vicinity of the airfield. This indicates that CFIT accidents do occur in areas without high terrain;
(i) In 30 accidents (one-fifth of the total sample), inadvertent VMC flight into IMC was a factor. Most of these accidents occurred in single-pilot operation flights, involving regional and air taxi operators. Seventeen of the 30 VJVIC-into-IMC accidents (56.7 percent) occurred in the en route phase.”
System upgrades, obstacles etc: Indispensable Upgrades.
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I have the TERR ALWAYS ON, whenever WX radar is not deemed necessary - as per the old rule of using one's all available equipment. While not essential in cruise, it adds a bit to the overall situational awarness...
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We have different displays for Terrain. In the Peak mode it is very usefull throughout the flight since you see with one glance how high the highest terrain is below you, very very usefull indeed if you have to get down in a hurry.
Policy is to use Terrain on on both displays from the preflight checklist on, however we are free to switch to radar whenever we like, it is advised to keep one screen in terrain though for departure or arrival, but we are free to deviate from that.
Policy is to use Terrain on on both displays from the preflight checklist on, however we are free to switch to radar whenever we like, it is advised to keep one screen in terrain though for departure or arrival, but we are free to deviate from that.
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Safetypee, thanks for the info. You're right, the ground is equally hard whether it is flat or peaked! The error chain often starts when you are unaware of what you are getting yourself into until it is too late.
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Our SOP is that terrain stays on the MFD at all times for reasons previously stated and wx is on each PFD. Wx depictions are independent between the two PFDs as well.
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Unfortunately our aircraft, as with most EFIS aircraft can only display terrain or wx on the MFD individually and no wx/terrain can be displayed on the PFD.
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We've got terrain on ND during descent in our SOP's as im sure all of you guys would. However, i tried looking deeper as to when exactly its supposed to be displayed and i drew my own conclusion when the it says during descent adjustment (FCOM 3.03.17). It makes sense to have it during the course of the flight so as to better evaluate descent strategies during single engine ops in cruise. However having said that i always believe one needs to be aware of minimum flight levels en-route on the day. In my company we always adopt the STANDARD strategy on 95% of our routes (OBSTACLE on the remaining high terrain airways). So, standard strategy always clears us of the lowest flight level accross the country, hence we are not encouraged to have it on in cruise. Instead, we usually have two different range settings on the PF and PNF sides for the Wx radar.
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If you have the ability to utilise both WX and Terrain at the same time, I find it incredulous that anyone would wish to select Terrain OFF at any time in flight.
Terrain serves a practical and essential purpose on every overland phase of flight, and on every departure and landing. As previously mentioned, Terrain is programmed to respond to obstacles as well as terrain, and furthermore is designed to incorporate warnings in the event of approaches that are displaced from the "norm" when terrain (or obstacles) may pose a risk to continued flight.
If the capability is there to use the equipment simultaneously with WX radar, any SOP;s should, IMHO reflect this as an essential requirement for all operations.
Terrain serves a practical and essential purpose on every overland phase of flight, and on every departure and landing. As previously mentioned, Terrain is programmed to respond to obstacles as well as terrain, and furthermore is designed to incorporate warnings in the event of approaches that are displaced from the "norm" when terrain (or obstacles) may pose a risk to continued flight.
If the capability is there to use the equipment simultaneously with WX radar, any SOP;s should, IMHO reflect this as an essential requirement for all operations.
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safetypee,
Our terrain displays turns on if it detects any dangerous situation, even when manually switched off. So we only use it as an extra awareness when operating in mountainous areas. No need to have it on always, when terrain is not a factor.
Our terrain displays turns on if it detects any dangerous situation, even when manually switched off. So we only use it as an extra awareness when operating in mountainous areas. No need to have it on always, when terrain is not a factor.
PA38-Pilot, the visual pop-up feature of EGPWS is one of the great alerting systems, and together with the audio alerts/warnings is an excellent attention grabbing device.
As for display selection procedure, its your choice. However, some of the incidents linked in #6 suggest that crews were ‘surprised’ by the sudden awareness of terrain, and in at least one instance did not believe the warning system. An advantage of using the terrain display is that it adds to situation awareness; it provides a capability to ‘look ahead’ and avoid the stress of sudden surprises.
With the use of ‘Peaks’ mode, the display should not be overly cluttered; at lower altitudes any terrain ‘clutter’ is probably good background information that is required for an in-depth understanding of the situation.
“… when terrain is not a factor”, presuming that you take off and land on every flight, then terrain is always a factor; … if you don’t ‘land’ then terrain is definitely a factor.
As for display selection procedure, its your choice. However, some of the incidents linked in #6 suggest that crews were ‘surprised’ by the sudden awareness of terrain, and in at least one instance did not believe the warning system. An advantage of using the terrain display is that it adds to situation awareness; it provides a capability to ‘look ahead’ and avoid the stress of sudden surprises.
With the use of ‘Peaks’ mode, the display should not be overly cluttered; at lower altitudes any terrain ‘clutter’ is probably good background information that is required for an in-depth understanding of the situation.
“… when terrain is not a factor”, presuming that you take off and land on every flight, then terrain is always a factor; … if you don’t ‘land’ then terrain is definitely a factor.
