REFINEMENTS/CORRECTIONS
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On reflection, it is disappointing how, on several occasions, I have pointed at something but have been slightly wrong in the detail and yet did not receive positive correction where the point turned out to be near enough – missing the opportunity to advance understanding. I am sure that regular readers of this thread will recognize this as I present the updates.
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I have long suggested that the a/c was referring to a navaid/ beacon that misled them – just look at how the following parameters fit the hypothetical scenario of an ad hoc trial/ demo of the new beaut ARS-6 and PRC 112 combo simulating an RV with an ejected pilot or an SF soldier:
(I have used input from others more conversant with ATC procedures and a procedural document for NATO CSAR of the mid 90s.)
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CALLSIGN
ZD576 was using the callsign F4J40.
The use of a tactical callsign suggests something like QRA and so would be appropriate for an a/c looking for, say, an ejected pilot who was using a PLB (eg the PRC 112) - as there is no record of an actual ejection in the area at the time, this would have to have been an exercise.
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INTERCOM SELECTION
The handling pilot’s intercom was found to be on UHF Guard (emergency)
From a 1998 doc,
Joint Pub 3-50.21
Chap IV Sec. 3. Search and Locating Methods
“Electronic Search. Initial radio contact with isolated personnel usually
occurs on an emergency (Guard) frequency …”
and the PRC system is UHF.
The same section goes on to describe rather well how the system operates and in particular that “…the AN/ARS-6 computes slant range and direction to the radio being queried.”.
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SQUAWK
ZD576 had the code 7760 selected.
From the same doc as above, regarding a helo in CSAR:
“Situational awareness can be further enhanced by succinct communications and code word procedural guidance, the proper display of transponder IFF mode 1 or 3 squawks …”
Thus, if such an exercise was going on, an SSR code other than 7000 would have been expected.
Whether 7760 had specific meaning (in other systems 7760 can have the meaning “Ground Transponders Tests/ Trials”) or it was an innocuous choice from the domestic code allocation (at the time this was the practice where confusion was unlikely as there was a shortage of codes for specific tasks) is a moot point – this scenario gives a possible explanation for the code not being 7000 that is more reasonable than a frenzied attempt to select emergency or that impact caused the movement of the selectors.
Further, they said in one call that they were doing something but unfortunately the verb was not distinct enough to be recognised in isolation – possibly, this could be recognised by someone familiar with code words.