Minimum Safe Altitude

[aviationdebrousse]

i have this nagging question about MSA. Consider that the MSA for a particular approach is around a VOR are the sectors bearing to the station or radials? The reason I ask this is because I was looking at a number of Approach Plates(Jeppesen) and the sectors if the MSA was referenced with a VOR indicated the bearing. In this chart would the MSA between bearing 180 and 270 be 15000?

Also if that's the case isn't it easier to describe then as R360 and R090 because Radials will be more precise than headings.


http://www.altairva-fs.com/training/images/Ayers/eyw.jpeg

[Boxshifter]

You are right the MSA is 15,000 ft in the sector mentioned.

Regarding use of bearings or radials please keep in mind that a MSA circle can be based also on NDB or a waypoint, e.g. the ARP is often used with RNAV approaches. So using bearings will always work.

[Intruder]

Also, look at it from a realistic point of view...

In the SE clockwise through NW sector, there is virtually nothing but ocean, and a bit of the city of Key West. The 1500' MSA makes perfect sense.

OTOH, in the NE sector, there is little but a few other keys and a bridge/causeway, EXCEPT a tethered balloon on Cudjoe Key that goes up to 14,000' or so. Therefore, the 15,000' MSA.

Also, the magnetic bearing from a VOR would overlie the radial, so there is no practical difference.

I would prefer that the MSA depiction show the outbound radial instead of an inbound bearing. However, since the depiction is on an approach chart, many people may tend to mentally place themselves with regard to inbound course/bearings. Hence (I assume) the use of the inbound bearing.

[aviationdebrousse]

i understand if the reference is the ARP or even the NDB. however in this example the chart specifically mentions a VOR.
I would prefer that the MSA depiction show the outbound radial instead of an inbound bearing

hence jst wondering why not specify radials to demarcate the sectors . tht way there is no ambiguity.

[fullyspooled]

edited due to misunderstanding

[aviationdebrousse]

Headings would be of no value to you ar all! As depicted on the chart shown, the sector identified with an MSA of 15,000 ft lies between QDM's of 180 and 270 degrees. (QDM being the magnetic bearing to the station, or fix being used as a reference point)It makes sense now. Never got around thinking along the lines of the QDM. Ofcourse the premise is that we are heading to the station and within the selected bearings To the station the MSA is 15000 feet.

Intruder guess that's what you were trying to tell me...jst took a lil time to sink in. thanks