It has often been discussed the necessity of being constinously aware of terrain when flying IFR.
This is abviously true for the arrival segment, but also en-route.
Icing, engine malfunction or stop, disorientation, incapacity to maintain level (orographic waves fo example) are few examples which come to mind.
We should indeed always know what altitude we can descend safely, hoping that temperature will raise above 0°C, level can be maintened or VMC conditions have been retrieved.
For the en-route segment, we should use altitudes available on IFR charts (Jeppesen):
Electronic devices or logs (such as the one generated through the autorouter) give us an MSA. The problem is I usally have 3 different values:
(Considering charts in the arrival sequence, I also took the habit to descend on vectors only with the georeferenced RADAR ALTITUDE CHARTS in sight, so that I can always crosscheck the clearance. But I don’t think it can be used in an efficient way en-route)
Another source of information could be GPWS. Recent snapshot from @Flyer59 showed values indicating altitudes of the terrain for the sector.
Then comes situational awareness tools such as Topo and Terrain functions on moving maps, Synthetic vision, or Oziexplorer, Peter often advertises us :-)
I guess those tools can provide some help in the worst cases, but they won’t tell you what altitude you can descend safely and you will request to the ATC.
In short, I would like to know what you are using en-route, to get at a glance the lower altitude you could descend safely, among all those (sometimes contradictory) informations we have.
Thanks !
PetitCessnaVoyageur wrote:
MSA on the autorouter log: what is it generated from ?
Shuttle mission terrain data, just like GRAMET. Below 5000ft, the MSA is 1000ft above the highest obstacle within a corridor of 5NM along the route, above 5000ft, it is 2000ft above the highest obstacle.
Just to add: MEA is usually not useful, since it is determined not only be terrain, but also by airspace structure.
In Sweden for example, you won’t find an airway below FL100, even in flat terrain. That because controlled airspace starts there.
achimha wrote:
Below 5000ft, the MSA is 1000ft above the highest obstacle within a corridor of 5NM along the route, above 5000ft, it is 2000ft above the highest obstacle.
Does this shuttle mission data actually include obstacles? I.e. if you have an antenna on a mountain top, does it take the tip of the antenna plus 2000 ft to be the minimum altitude?
Could you also use grid MORA for this?
Rwy20 wrote:
Does this shuttle mission data actually include obstacles? I.e. if you have an antenna on a mountain top, does it take the tip of the antenna plus 2000 ft to be the minimum altitude?I can’t imagine it does, but all significant obstacles should be in the relevant AIP and thus (in Europe) in the EAD database. Tools like SkyDemon have the obstacles and I guess they get it from EAD or other official sources.
@Achimha, does the Autorouter use that obstacle data?
Could you also use grid MORA for this?
Absolutely!
Airborne_Again wrote:
Absolutely!
We didn’t have much answers from the “pro”, but I guess they fly so high they don’t mind :-)
In real situation, I actually use the Grid Mora as the most valuable data: it is easy to find (with JeppFD, in seconds), and is correct for a “square region”.
Flying IFR, we never are on airways, so MEA and MOCA are of low value.
PetitCessnaVoyageur wrote:
Flying IFR, we never are on airways, so MEA and MOCA are of low value.
I think this would deserve further explanations. 
Actually my question was meant to be addressed to Achim and other autorouter folks, to read if they could usefully integrate grid MORA where they now use terrain height.
Airborne_Again wrote:
all significant obstacles should be in the relevant AIP and thus (in Europe) in the EAD database
should maybe, but they aren’t. I have 212 obstacle (areas) in my EAD dump, all of them are associated to some airport, and include things like glideslope antennae and RVR measurement equipment. So it’s useless for enroute.
Aviathor wrote:
I think this would deserve further explanations.
There is some exaggeration in my statement :-) But, as for my little experience, we often have shortcuts (I mainly fly south of France) which put us “off road”, when flying between FL100 and 150. In that case, I have no practical means to know if I am 3, 5 or 15nm off the track, so Grid Mora becomes much more useful to have a quick and safe information.
But I would be happy to know, how more experienced pilots, proceed to stay aware of surrounding terrain when IMC.
