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#22
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Andrew Sarangan wrote: This is some good info about MSA that I did not realize. But I am still a bit confused. The AIM says that MSA provides 1000 ft clearance over all obstacles, implying that it satisfies the minimum IFR altitudes (in non-mountainous areas). Is this statement incorrect? Also, if the MSA is not accurate for IFR, how much extra work is it anyway to produce a chart with an MSA that conforms to IFR standards? The numbers are already available from the enroute charts, so it can't be that difficult, right? The AIM parrots the cartographic standard set forth for MSAs. What I explained is the reality of how they are constructed. They are intended for emergency use, and with today's technology their value for that use is questionable. In any case, the altitude you really want is the center's minimum instrument altitude sectors on a moving map. Or, approach control's MVA sectors on a moving map when in a TRACON's airspace. Those are coming, because the FAA recently relented and agreed to release them (well, the MVAs anyway). It will be a while though. |
#23
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J Haggerty wrote: MSA's do not ensure NAVAID or radio reception, and may even contain sectors that are known areas of no signal coverage. They just ensure 951 feet of obstacle clearance within the specified distance from the NAVAID. True, except 951 is no longer permitted per AFS-420. No more rounding down on TERPs ROC. |
#24
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MSA's do not ensure NAVAID or radio reception, and may even contain
sectors that are known areas of no signal coverage. They just ensure 951 feet of obstacle clearance within the specified distance from the NAVAID. JPH Andrew Sarangan wrote: wrote in message ... Andrew Sarangan wrote: I realize that that is what the AIM says, but why are they to be used for emergencies only? I always interpreted the MSA as the minimum altitude to use when flying off-feeder routes (direct to the IAF), sort of like the OROCA when flying off-airways. In many countries MSAs are operational altitudes. They are not in the United States. And, in a designated mountainous area you are required by 91.177 to have 2,000 feet vertically or 4 miles laterally when off a published route or segment. MSAs are not IFR altitudes, routes, or segments. I agree that MSA does not satisfy the altitudes in mountainous areas. But in nonmountainous areas MSA does satisfy the altitude requirements. What am I missing here? |
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