sprucegoose
Creeeeak groooaan, click, sproing, sounds of memory booting up.
I suspect the answer may well be in the question.
Locator beacons MF L(lower power than) are subtly different to MF NDB and one can be easily confused with the other. The Locator ranks after the NDB in order of precision.
See Jepp Radio Aids AU21-22.
As I recall it, Locator beacons usually radiate at less than 50 watts and are used primarily to locate the aircraft near an aiport runway centreline prior to or as part of an approach, or as an LOM or Locator at a OM site as an IAF on a Localiser or ILS.
I suspect that those Locators that now appear to be bereft of any apparent proximity to a localiser/ILS (such as ARC and MEA at AMML)are the remnants of an ancient VAR system, but are still useful.
It is their lower power and usually low frequency which limits their usefulness as tracking aids unless 2 are colocated and can be used concurrently/contiguously or whatever.
AMML Twin Locator Rwy 17, ARC and MEA are only 5.6 miles apart
I also suspect that although the AIP appears silent on the matter directly, or I can't find it, it is implied in Track Keeping "only those aids which specifically define the relevant track must be used for tracking keeping", provides the requirement for them BOTH to be operating.
Further I seem to recall that under the IFR Minimum Required Nav Systems for RPT; and Charter/Airwork when using NDB's (Locators) as the primary means of navigation that two ADFs are required.
To satisfy the monitoring requirements each Locator being used during the approach must tuned and both monitored for operation.
Seems to me that therefore you need both Locators serviceable and 2 serviceable ADFs to legally conduct a Twin Locator.
BTW thanks it was great company the other night
