Marker Becon Radio

When is it that you must have a marker becon radio?

Most ILS approaches today have eliminated marker beacons as an element of the approach. These were used to provide positional reference along the localizer. Most precision approaches today allow GPS, VOR or DME fixes to establish position. The long term intent is to do away with ground based reference totally (VOR, NBD, Localizer) and replace these with precision GPS. Ultimately, this will likely save the government a great deal in terms of station maintenance and at the same time, will allow approachs at locations where they don't curently exist and/or make more precise approaches at current instrument airports. If you're looking at investing in a marker beacon receiver, don't bother.

No MB for me

Thanks, Terry.

I'm just a VFR guy at this point. Maybe some day get my IFR rating.

A friend said that I must have an MB radio if I am going to do ILS approaches. In all my reading on the forums, I had not heard much about marker becon radios or even knew the requirement if there was one.

(My panel will include Dynon D-100, SL30, GNC 300XL)

Audio panel

Hi Sam,
As Terry pointed out, they are used during an ILS approach. They operate on 75Mhz and transmit straight up and you know when you're over the outer marker, around 5 miles from the threshold. This is usually the point at which the approach descent starts as you follow the glideslope needle.

Most audio panels have a built in marker beacon and lights because it's such a simple, one frequency unit.

Regards,

Sam:
There is no requirement for a beacon receiver in order to fly IFR. Currently on ILS approachs there is a requirement for positional fixes which can be satisfied by a beacon receiver (undergoing phase-out as I indicated earlier) or some other means. If you have no means to verify position, the approach can still be flown, but essentially becomes a non-precision approach. I encourage you to get the instrument ticket as it will not only broaden your AC usage and increase your weather knowledge, it will also help you to become more precise in your every day flying.
Terry

Sam,]

I disagree with Terry, but it's a bit of a legalistic issue rather than a practical one.

Unless your GPS is certified IFR and you keep the data base updated, it isn't legal for approaches. Since none of us pay any attention to that...

Lacking a MBR, there are substitutions that can be made but the approach minimums may be degraded. Best substitute is a co-located NDB, but I'll just bet a dollar to a hole in a donut you're not installing an ADF! Radar is a great substitute if you really need a position fix. Usually you just fly the LOC until intercepting the GS and track it. But you are giving up a bit of data. (Then there's always sneaking a peek at your hand-held GPS to see when you cross the OM.)

Here's the gotcha. For a full ILS approach, you also need an inner marker. There is no substitute for an IM, and the books are silent about the affect of no IM. Without it, I must conclude that the ILS approach isn't legal and it reverts to non-precision LOC. Again, I don't think anybody really gives a Rhett Butler; track the GS until Decision Height. That's my reading of the FARs and AIM, because I considered the same question as you for the first RV.

A cheap way to get a MBR is a kit offered by RST Engineering. Don't overlook the extra complexity of installation.

John Siebold

RV7ator said:

Sam,]


Here's the gotcha. For a full ILS approach, you also need an inner marker. There is no substitute for an IM, and the books are silent about the affect of no IM. Without it, I must conclude that the ILS approach isn't legal and it reverts to non-precision LOC. Again, I don't think anybody really gives a Rhett Butler; track the GS until Decision Height. That's my reading of the FARs and AIM, because I considered the same question as you for the first RV.

John Siebold

Click to expand...

Not a lot of airports have an IM installed on the ILS. Not needed for a "full" (cat I) ILS. In fact, there are plenty of ILS approaches without an OM or MM installed. There just needs to be a way to determine position on the approach, but a VOR intersection or DME fix will work. The approaches to LAX runways 6 and 7 are an example. The OM would be about 7 miles out in the Pacific Ocean.

John Clark
RV8 N18U
KSBA

That's true, John. Not all approaches are the same. What I'm addressing are the fringe aspects (in the same league as the definition of "congested area"). F'rinstance, where I frequent, the missed requires an ADF. If it's charted, like an IM, do you comply or simply not tell anybody? Pretty unlikely anyone's ever going to care, and an MBR is not always, but sometimes, a requirement, if not simply an aid (sure beats frantic button pushing if you're single nav looking for a VOR cross-fix).

John Siebold

John:
You have referred to "required" equipment. Please see FARs concerning required receivers. Not sure if you are instrument rated or if you are planning to acquire and use this rating, but the important part of my earlier posting was that much of what we have used to date is being phased out and replaced by GPS. If you receive Jepp or NOS updates, you will see literally dozens of new non-precision GPS approachs added with every issue as well as the beginnings of precision GPS. My recommendation was to not bother with MB receiver -its dying. If you're going to fly in the system today and in the future, you're going to need GPS and it's going to have to be certified and updated. As the the "requirement" to have an IM receiver on board to fly a precision approach, not so. Please see FARs.