Marker Beacon ?

[whereamI]

Why is there a switch to select the sensitivity for your marker beacon reciever? It is a High/Low switch, which confuses me since the AIM specifically states your marker beacon reciever should always be set to the "Low" sensitivity setting. If this is the case, why the switch?

 

[EagleRJ]

If there's a high/low sensitivity switch, the reason you want to keep it in the low position is to limit your reception of the beacon to the time you are directly over it. By having the shortest reception time possible, you can be more accurate defining your missed approach point, for approaches that use it.

Not really sure why marker beacon receivers have a high sensitivity setting. The marker beacon's signal is broadcast vertically, so you can only receive it when you are more or less over it. It's probably a throwback to the days when airway radio beacons were in widespread use. In the high mode, you could still recieve the signal even at higher altitudes.

 

[KnowledgeSeeker]

That good guess about the high setting is correct...for use at altitude.

 

[whereamI]

Thanks

That kinda makes sense. I understand the reasoning for leaving the switch in the "Low" setting (ie. only recieve the signal for the prescribed distance of time on the approach), I was just curious as to why the he!! you would make a switch if it is always supposed to be on one setting. The plane I am flying is definitely not new, so it could be a throwback to the days of navigating via airway beacons and such.

 

[Kingairrick]

My switch stays in the low position all the time. However, the annunciator flashes every few minutes or so when I'm flying on airways (crossing over lots of airports.) I cruise in the high 20s/low 30s, so I'm not sure about the altitude answer.
As to the origional question....Anyone,... anyone,.... Bueler?...

 

[starvingcfi]

wow. high 20's/low 30's. must be nice. i hit 7000' yesterday. it was a rush.