[Milsurplus] Landing Indicator?

[Mike Morrow]

Dave wrote:

>> Can someone tell me what this dual needle meter was used with, please?
>>
>> Westinghouse CAY-22318
>> Landing Indicator
>> Part of Model ZA Equipment

John wrote:

>The ZA system was the first operational all-weather landing aid.  The ZA 
>system used two receivers.  The first was the output from a 190-550 kHz 
>command reciver.  This output was filtered to get the 90 & 150 Hz modulation 
>for the course needle information.  The second receiver, a ZA 93 MHz 
>glideslope receiver, provided vertical needle indication. (see Gordon 
>Elliot's article, CQ, October, 1965, 34-37)

That's a real good description of the ZA.  The land-based portion was called the YB.  The commercial name for this system was the "Air-Track" system, and if you search the web for that and ZA, YB, and ILS you'll likely find a bit more info and history.

I've never been able to confirm this, but...I think the ZA developed into the ZAX, which developed into the AN/ARN-9, which used a similar (but not identical) cross-needle unit called the ID-24/ARN-9.

If you've ever read in AN/ARC-5 maintanance manuals a reference to the navigation receivers providing output to an instrument landing system, this is the ILS to which the manual refers, though I think it was likely the AN/ARN-9 and not the ZA.  The R-23 and 24/ARC-5 receivers have a special audio output connection, made to the ILS through the MX-19/ARC-5 front panel adapter box.

This USN system deservedly went into the dumpster of technical history due to the later development of a very different, much superior USAAF ILS, which used the RC-103 (BC-733) VHF localizer and AN/ARN-5 UHF glide slope receivers.

I'm hoping someday to find manuals for the YB and the AN/ARN-9.  Judging from what I've read in the ZA manual, the Air-Track was not a real easy system for the pilot to use compared to the USAAF's ILS.

Mike / KK5F