O.M.I. Markers... where?
 

Hi, I have flown a hired aircraft that had the three light Outer, Middle and Inner Marker system fitted, but it did not activate on the route I flew.

I just wonder if there is anywhere in the UK that still uses this system, and do you need to switch it on, or tune it in, on the plane?

Most of them are gone now. I think Filton had a marker I seem to remember it scaring the poo out of me when it went off.

Its usually on but you have to have the intercom set up to hear the audio on your head set. I would suggest though you don't turn it on though and leave it. It can give you quite a fright if triggered and your not expecting it.

Offhand I can't think of any 75mhz fan markers still operating in the UK, with ILS' using DME nowadays.
But then I could be wrong!

I think I've seen them illuminate before while flying - can't for the life of me remember where though; and like Mad_Jock, it made me jump a bit too! I don't like unfamiliar lights flashing on the panel while flying.

Saw them way back in '74 at Brmingham and Ostende. I'm only guessing but I would think they're automatically switched on when you switch on the ILS receiver.

Correct...

Wrong. It is not connected in any way with the ILS receiver, and for a reason: besides ILS, marker beacons are used in NDB / 2NDB approaches, being collocated with the NDBs. Some countries (e.g. Russia) still have plenty of these. Last time I saw the marker light blink was at LKPD, they still have an active outer marker.

I think in most cases the receiver itself is permanently on, but its audio output can be turned on and off with one of the switches on the audio panel.

Cranfield's AIP entry says it still has an OM and MM.

Mostly gone !
 

For the VFR pilots the outer & middle markers are usually associated with an ILS system, the outer issued as a system check, as you get the audio and light you check that you are passing the correct altitude with the glide slope centered ( Go around if anything is not correct) the middle marker is almost always placed at the CAT 1 decision point and it should prompt you to see the approach lights or runway or go around.

history the inner marker was in the early days of ILS placed at the runway threshold, it those days there was no hard decision altitude and it was intended to help the pilot find the runway, this of course was found to be dangerouse to say the least and this practice was discontinued. Some inner markers could be found on airway centerlines, the last one I can remember was on Killiney hill just south of Dublin.

As said above DME has largely taken over from markers as the DME station can be securely placed on the airfield, Markers being placed about four miles from the threshold where very vulnerable to vandalism and theft of the wiring and electrical equipment and this is why at least at two airfields I know of they have been withdrawn in favoir of DME.

As said above Cranfield and Ostend still have markers and there are quite a few once you get outside Europe, there have been experiments using low powered voice transmissions on the marker frequency to warn aircraft on the ground that they are approaching the active runway holding point, this is intended only for CAT 3 operations.

I hope this has been helpfull !

Interesting. Did an approach at Cranfield on my IMCr re-test, didn't notice any markers going off, nothing mentioned about them by the examiner.

first off, outer and middle markers were at one time used with standard beam approaches, even before ILS approaches were widespread.

inner markers were and are still used in CAT 2 apchs.

Middle markers may also trigger glidepath extension in certain planes.

did your particular plane have a small switch indicating HI/LOW?NORMAL?

flip it to high and you will hear it better...it is also helpful in using this switch to know your position. high warns you that you are approaching the marker, then switch to low/normal and start your time when you hear/see the flashing light again.

the high low isn't volume, its sensitivity.

as to the number or location of marker beacons in england...why not ask each control tower you are near or radar facility? or ask an instrument flight instructor.

Doesn't say much for your accuracy.... :p :p :p

Cranfield still have an OM (co-located with CIT), but it was notammed as out-of-service recently.

A MM is listed on the plate, but I can't remember seeing it go off when doing IMCr.

R.

Kidlington used to have a non-standard marker on the 'NDB-DME 100 deg to Aerodrome' (which most of us remember as the NDB 09 approach before they closed 09-27, although we never landed off it anyway). It radiated the Morse letter 'K'. It marked a step-down fix on the approach, at which you should be not below 1250(980).

I see from the latest AIP chart that it's no longer there, and this is now a stepdown fix at 2.8d (so with no DME your minimum becomes 1250(980) but with DME it's 800(530) -that was always the case if you couldn't receive the marker).

Anyone know of any other non-standard markers i.e. not OM, MM or IM on an ILS?

Also this thread has prompted me to notice that at my home base, Benson, the MM has vanished - shows how much attention I'm paying on ILS approaches! Mind you with radar monitoring it was a bit pointless.

Tim

Tim the marker & NDB got taken out due to vandalism and was replaced my the DME.

Just seen a post on the Australian forum, where they are asking 'What is an ADF ?'
.

Aussie Direction Finder? :)

HTC

I think, as mentioned above by others in 2013, that there are indeed still markers at Cranfield. I flew an ILS into there on Friday night and heard some unexpected but clearly intentional tones in my headphones during the approach. It took me a few moments thought to remember about markers. Then again, I cannot see markers in the AIP entry.

NDB’s...... have they gone in Australia ?
 

About twenty years back I was on my way from Sydney to Townsville in a TB20 when just north of Brisbaine ( and having not much else to do ) I tuned the Bunderburg NDB as this was my next waypoint and about an hour and a half away.

To my complete surprise the ADF sprang into action pointing in the right direction with the morse ident loud & clear. Being more aquanted with the short range NDB,s in the U.K. I got out my copy of the Australian air pilot to discover the output of this NDB was 2000W !!........ I guess GPS has sent the NDB the same way as the radio range station.

There are some still about here. Our CAA in UK seems to be unwilling to hand out instrument ratings to anyone who can't do an ADF hold and approach so is reluctant to encourage this new fangled GPS stuff in case there are no ADFs to test for proper piloting skills.
[Slightly tongue in cheek ..... but I'm a bit worried there may be some truth in it]