[Milsurplus] [ARC5] OT: What is the purpose of the 4th pointer on my Kollsman 671CLU-4-038 pressure altimeter?

[Sheldon Daitch]

Looking at eBay item 351778486635, it makes sense, now.

The  orange triangle is a reference altitude marker and is set with the lower right know.

This unit is a high end altimeter system, and as noted, from a B737/747 system.  Looks like it is from the older systems, steam gauges as some pilots call them.

I've never flown an aircraft with that high end equipment, not on my budget, and I have to make some guesses.  I don't think the orange triangle marker is settable other than somewhere in the 1000 foot range, and usually set per one B-737 ops manual for the minimum descent altitude on an instrument approach.  I also suspect that altimeter pictured also has an output to an alerter in the  cockpit to tell the pilots they are at MDA.




73

Sheldon



________________________________
From: ARC5 <arc5-bounces at mailman.qth.net> on behalf of Clare Owens <clare.owens at gmail.com>
Sent: Tuesday, July 12, 2016 1:18 AM
To: Discussion of AN/ARC-5 military radio equipment.; armyradios at yahoogroups.com; Milsurplus
Subject: [ARC5] OT: What is the purpose of the 4th pointer on my Kollsman 671CLU-4-038 pressure altimeter?

Hi All,

The altimeter has the usual three pointers in its center, for 100/1000/10000 feet.  But it also has a little triangular pointer that rotates around the edge of the dial and moves at about the same speed as the 100 foot pointer.  When the three normal pointers are at zero, the one on the edge ia pointing to just a little below 6.8.  Seems odd and I can't find any reference to the edge pointer on line.

It looks like this unit needs to be recalibrated and I've found instructions for that.

The altimeter has the typical Navy "US with anchor" stamp on its back.

Any Navy aviators out there?

Thanks,

Clare

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