Marker Beacons and Compass Locators

[safepilot24]

Can an experienced pilot provide some insight on why a compass locator is co-located with a marker beacon? I.E, what is the significance of doing this, when marker beacons work just fine?

Also, I understand the power ouput of a marker beacon is not more than 3 watts. Is the average power output of an NDB around 400 watts?

Purpose of the outer marker: On precision approaches, to either serve as an altitude check if you are right on the glide slope, or passage of the marker occurs right around glide slope intercept. On non-precision approaches, it basically is there to serve as the FAF, beginning of final approach segment. Correct?

Much appreciated.

 

[100LL... Again!]

The compass locator can be used as an FAF from which you may fly the approach on your own navigation.

Think about it: there is no way to navigate directly to a marker beacon, right?

If I recall correctly, way back years ago if the OM was out of service, minimums were raised slightly. There turned out to be no good reason for this, so it was changed.

Incidentally, many Canadian ILS's have the slope intercept point a long way before the OM.

Several approaches in the US have an ILS with no compass locator, no marker beacons, no DME, and no crossing radial. Just a slope intercept altitude. This is all that is required.

 

[pilotman2105]

100LL is on the money for that one.

Regarding the different power output for NDBs, there are power outputs (and maybe service volumes) of NDBs. Check the AIM.