Grid Mora

[PC12Cowboy]

MORA and Grid Mora which charting uses this and whats its definition???
Thanks

 

[DC8 Flyer]

Its been a while, forgive me it its not 100% correct.


Grid MORA (minimum off route altitude) on VFR sectionals shows the highest altitude of an obstacle, rounded up a 100 feet or so, in that grid. This is the one NOT to use as a minimum altitude.

Grid MORA on IFR low enroute charts is shows the same thing as the VFR chart except now it is 1000' above the highest obstacle. This is the altitude you use to come up with a MEA for doing off route navigation. Note, you can also break out a VFR sectional draw your course, measure 4 miles either side and use an altitude 1000' above the highest obstacle there and usually get a much lower MEA, BUT ATC usually doesn't like that.

Route MORA. I have never seen or used one, but in the JEPP glossary it is a route that can be activated by ATC, is 5 miles wide? and is usually between two fixes, not necessarily navaids. It provides the same as a MEA 1000 in non mts and 2000 in mts. This one is kinda weird, like I said never used or seen one, but I do remember it being in the glossary of the JEPP plates.

Hope this helps!

 

[PC12Cowboy]

so its a OROCA...lol...ok different terms....thanks,,,,
so MORA isnt in the back of the FAR/AIM by jeppesen...so it is a jepp term?
<suffering from oldtimers me thinks, lol

 

[bafanguy]

PC12,


MORA is a Jepps-invented term/altitude. I don't know if they still have it on their website, but Jepps produced a series of articles on the interpretation/use/symbology of Jepps enroute and approach charts...called "The Chart Clinic". Still the best basic source of info I've seen. Jim Terpstra at Jepps told me they were thinking of putting it out as a book; don't know if they did. Article #11 deals with MORA's.

If you can find these articles, all your questions will get answered...right from the source.

 

[JetBlast2000]

MORA and Grid Mora which charting uses this and whats its definition???
Thanks

MORA and Grid MORA refer to IFR charts. MORA gives obstacle clearance 10nm either side of an airway for mountainous and non-mountainous terrain (1000/2000ft). Grid Mora gives 1k-obstacle clearance below 5k and 2k above. This number located inside a lat/long grid and is either magenta for alt. above 14k or green for alt below 14k (I think I’ve got the colors right). On a VFR chart that number in the grid is called the MEF (max field elev.). It provides 100ft above man made objects and 300ft above natural objects rounded up to the nearest 100ft.

 

[Singlecoil]

Its been a while, forgive me it its not 100% correct.


Grid MORA (minimum off route altitude) on VFR sectionals shows the highest altitude of an obstacle, rounded up a 100 feet or so, in that grid. This is the one NOT to use as a minimum altitude.

Not to nitpick, but I can add a little there. On the sectionals they are called Max Elevation Figures or MEF. For the value, it depends on whether the obstacle is man-made or natural. For man-made obstacles, they round up to the next 100 feet, then add another 100 feet. For natural ones, like mountains, they round up to the next 100 feet, then add 300 feet.
The way it was described to me was that someone could build a 199 foot tower on a mountain and not have to notify anyone, so they add in another 200 foot fudge factor. For man-made obstacles, they have to notify the powers that be if they make it any taller than what was previously reported.

For example, Mt. Rainier is 14,411. The MEF on the sectional (and I'm going from memory here) is 14,800. Round up to 14,500, then add 300 feet. I'm sure you can find a MEF based on a radio tower, lets say the tower is 807 feet. The MEF would be 1000 feet. Round up to 900 and add 100.

Grid MORA's on the enroute charts are derived by adding 1000 to the MEF's for a grid in non-mountainous areas, or 2000 to the MEF's in designated mountainous terrain.

 

[DC8 Flyer]

Awesome! Thanks for clarifying that. Learn something new everyday.