Blue and yellow, does anyone remember?

kgruber

kgruber

Final Approach
Joined
Jan 3, 2007
Messages
5,080
Location
Western Washington
Display Name
Display name:
Skywag
Is there anyone here who is old enough to remember why the old VOR/ILS indicators had blue and yellow markings.

images


I remember "We're in the blue!"
 
kgruber said:
Is there anyone here who is old enough to remember why the old VOR/ILS indicators had blue and yellow markings.

images


I remember "We're in the blue!"
Click to expand...

The charts still have the colors as represented by greyscale shading. It was to provide a pilot for a reference for normal and reverse sensing.

Now, can you tell me the names of the various L/F range station orientations? :rofl:
 
The charts still use the blue/yellow, clear/shading protocol. But no modern indicators do.

Oh well, I am old enough to have flown when AN ranges still existed, but never flew one. I grew up along with VOR. But seem to remember "A", "N", and "On the beam," from listening to my heros.
 
704967594_tp.jpg

And the two little extra triangular pointers on this altimeter are for... what, exactly?

dtuuri
 
I just learned something new. That's pretty cool stuff!
 
kgruber said:
Is there anyone here who is old enough to remember why the old VOR/ILS indicators had blue and yellow markings.

images


I remember "We're in the blue!"
Click to expand...

Most of the planes I trained in had ones that looked like that.
 
kgruber said:
Is there anyone here who is old enough to remember why the old VOR/ILS indicators had blue and yellow markings.
Click to expand...

Do you mean why were those particular colors chosen? Perhaps they showed up best under red cockpit lighting.
 
aterpster said:
Now, can you tell me the names of the various L/F range station orientations? :rofl:
Click to expand...

Do you mean the Morse letters of the airway beacons in sequence? WUVHRKDBGM, the memory aid was "When Undertaking Very Hard Routes Keep Direction By Good Methods." I never flew a LF airway but I have a lot of old books and charts.
 
This is the blue and yellow that I like!
 

Attachments

  • 20141109_144414.jpg
    20141109_144414.jpg
    1.5 MB · Views: 40
Last edited:
dtuuri said:
View attachment 38068

And the two little extra triangular pointers on this altimeter are for... what, exactly?

dtuuri
Click to expand...

Ok, I'm only givin' y'all one more chance to hijack this thread. I know some of ya still have this kind of altimeter and are puzzled by the function of the triangles, er, I think you are anyways. And there must be somebody who actually knows!

dtuuri
 
dtuuri said:
Ok, I'm only givin' y'all one more chance to hijack this thread. I know some of ya still have this kind of altimeter and are puzzled by the function of the triangles, er, I think you are anyways. And there must be somebody who actually knows!

dtuuri
Click to expand...

Altitude bug? :dunno:

I'm too young to know!
 
dtuuri said:
Ok, I'm only givin' y'all one more chance to hijack this thread. I know some of ya still have this kind of altimeter and are puzzled by the function of the triangles, er, I think you are anyways. And there must be somebody who actually knows!

dtuuri
Click to expand...

Here's a guess---

It looks like the little triangles are telling you the altitude difference between a standard day (29.92” Hg) and the pressure actually dialed into the altimeter’s window (29.5” Hg), i.e. 29.92" -29.5", or 0.42” Hg. Converted to altitude, that’s 420 feet.

The inward facing triangle is pointing at 4 (hundreds of feet) and the outward facing triangle is pointing at 2 (tens of feet).

The pressure altitude is 420 feet off of the indicated altitude, or vice versa.

Like this?:
Altimeter.jpg
 
Last edited:
register@teamandras.com said:
Here's a guess---

It looks like the little triangles are telling you the altitude difference between a standard day (29.92” Hg) and the pressure actually dialed into the altimeter’s window (29.5” Hg), i.e. 29.92" -29.5", or 0.42” Hg. Converted to altitude, that’s 420 feet.

The inward facing triangle is pointing at 4 (hundreds of feet) and the outward facing triangle is pointing at 2 (tens of feet).

The pressure altitude is 420 feet off of the indicated altitude, or vice versa.

Like this?:
Altimeter.jpg
Click to expand...

I was thinking the same thing, but that arrow at the top is pointing to 40 feet, not 20. ;)
 
See discussion of "reference markers" here. (Also called "reference marks" there.)
As I understand it, you set the little guys to QFE and your altimeter should read 0 upon landing.
(At the airport, the tower or FBO would set a similar instrument to show 0, and broadcast on the radio the altitude indicated by the reference markers as the "QFE setting", similar to the current way of reading inches of mercury units inside the Kollsman window and setting either "0" (for QFE) or field elevation (for QNH) on the big pointers.)
(Discussion on this thread.)
 
Last edited:
RotorDude said:
See discussion of "reference markers" here. (Also called "reference marks" there.)
As I understand it, you set the little guys to QFE and your altimeter should read 0 upon landing.
(At the airport, the tower or FBO would set a similar instrument to show 0, and broadcast on the radio the altitude indicated by the reference markers as the "QFE setting", similar to the current way of reading inches of mercury units inside the Kollsman window and setting either "0" (for QFE) or field elevation (for QNH) on the big pointers.)
(Discussion on this thread.)
Click to expand...

I'm not sure those references help me understand. I "know" from an old crusty WWII pilot/CFI that the reference marks had everything to do with QFE, but I can't remember what he said (over 40 years ago!). I "think" the triangles go the opposite direction from the hands. I can probably deduce the procedure they used to get QFE if this is right:
  • The picture could be of an altimeter at SL with a local setting supposed to be at 30.25.
  • If the hands were turned from SL down to pressure altitude of 29.92, then the triangles would show zero.
  • If the hands were turned further to where they are in the photo (below SL), the triangles would go the other way up to where they are shown.
Agreed so far? Anybody?

dtuuri
 
Last edited:
dtuuri said:
I'm not sure those references help me understand. I "know" from an old crusty WWII pilot/CFI that the reference marks had everything to do with QFE, but I can't remember what he said (over 40 years ago!). I "think" the triangles go the opposite direction from the hands. I can probably deduce the procedure they used to get QFE if this is right:
  • The picture could be of an altimeter at SL with a local setting supposed to be 30.25.
  • If the hands were turned from SL down to pressure altitude of 29.92, then the triangles would show zero.
  • If the hands were turned further to where they are in the photo (below SL), the triangles would go the other way up to where they are shown.
Agreed so far? Anybody?

dtuuri
Click to expand...

Here is the way I understand it.
1. The little pointers represent small replicas of the big hands, in that the bigger (outer) shows 100's of feet, and the smaller (inner) 1000's.
2. The little pointers are interconnected (via internal gearing) to the Kollsman setting (but go in opposite direction to the big hands when you turn the setting knob), and are *not* affected by altitude/pressure -- therefore they are essentially indicating the same information as the Kollsman setting, in different units.
3. Based on the above, focusing on the Kollsman and the little pointers, we see that Kollsman in the photo is telling us we are approx. 0.4" Hg below SL ISA pressure (29.92 - 0.40 = 29.52" Hg), and this matches the little pointers (bigger pointer showing 400' *above* SL, smaller pointer showing the same in the 1000's scale).
4. Now we don't know two important things: what height was this photo taken (but let's assume near SL), and is the unit calibrated (let's assume it is).

So based on the assumptions in #4, here is one hypothetical scenario about this particular unit:
The unit was placed at SL, where the prevailing pressure was 29.52" Hg, so the unit read 0 feet (on the big hands) at that point, and the Kollsman read 29.52. The small pointers at that point indicated 400 feet.
If the tower announced to an aircraft with a similar unit, "QFE 400 feet", and the pilot set that in his instrument on the little pointers, since his unit works the same as the ground unit, it should indicate 0 ft (on the big hands) upon landing.
Now, if after setting the Kollsman to that value the local air pressure at the airport changed to 30.68" Hg (i.e. high pressure system moved in), the big hands would indicate -760 ft, as they do in the photo (assuming no further corrections to the unit).
In other words, to greatly simplify everything, this operates just like a normal modern altimeter, *except* it has an extra pair of small pointers that are mechanically interconnected to the Kollsman setting (only).
Another way of looking at it is the small pointers tell us how high we need to be above ground in a standard atmosphere to get the current ground level pressure.
The only advantage I can see is to perhaps allow wider setting range than the Kollsman window allows (+/- 5" vs +/- 1" ?), but that would be perhaps in the eye of a hurricane or otherwise unusual weather systems (see here for some records: http://www.crh.noaa.gov/dlh/?n=101026_pressurerecords ).
 
Last edited:
Here's an explanation straight from the inventor's mouth. According to Paul Kollsman’s 1931 reissue patent no. RE18306 (page 4, lines 110-127):

An important use of the instrument occurs when the aviator desires to descend for landing. He then obtains, as by radio message, shortly before landing, the barometric pressure at the landing field expressed in feet altitude, and sets the reference mark accordingly. Assume that the altitude corresponding to the barometric pressure at the landing field is 300 feet. Then the reference mark 41 may move counterclockwise, to the scale numeral 7, and the pointers including pointer 22 may move counterclockwise. The pointer then will indicate the altitude above the field and will read zero when landing. The aviator is thus assured of an accurate landing guide, especially under conditions of poor visibility as in fog or at night.
Click to expand...

Kollsman_Patent_Fig3.jpg
 
register@teamandras.com said:
Here's an explanation straight from the inventor's mouth. According to Paul Kollsman’s 1931 reissue patent no. RE18306 (page 4, lines 110-127):



Kollsman_Patent_Fig3.jpg
Click to expand...

This makes sense. According to this, the "altimeter setting" envisioned by Kollsman in this patent is in "feet altitude", not inches Hg (or pressure).
The little pointers do in fact give us "feet altitude", e.g. 400 feet UP when the pressure is 29.52, so the polarity makes sense.
The old altimeters were perhaps designed to allow for both pressure and altitude based settings, and over time the latter became deprecated.
Kind of ironic, because today we associate Kollsman with that little window and the inches Hg setting, but perhaps he added that later.
 
RotorDude said:
My suspicion is that this unit has been tampered with, since the Kollsman setting indicates "220 feet" low, while the little pointers are reading -870 feet.
The big hands reading is irrelevant, since it depends on the current pressure.
The other unit, OTOH, seems pretty much dead on.
Click to expand...

I dunno, it fits my logic so far. I haven't yet studied the above references and posts, but while I'm at it, here's one from January 1948 Flying Mag.

dtuuri
 
IIRC the markers get set to field elevation and will line up as QFE when QNH is set in the window rather than having the needles at zero with a QFE setting.
 
Henning said:
IIRC the markers get set to field elevation and will line up as QFE when QNH is set in the window rather than having the needles at zero with a QFE setting.
Click to expand...

If you set QNH in the Kollsman window, that will change the markers, so what you suggest can't work.
If you set the markers (using the Kollsman window) to field elevation, the Kollsman will never change, regardless of the ambient pressure.
Also, field elevation can easily exceed several thousand feet, while the Kollsman and little pointers will likely get pegged at +/- 1000 feet (or +/- 1" Hg).
 
Here's some insight as to how the altimeters were set to "field pressure" using the Kollsman window to read QFE. Before takeoff (and before this procedure), I guess they simply set the altimeter hands to zero and read the "field pressure altitude" off the reference triangles as "xxx feet above/below" the standard datum of 29.92 and cross-checked it with the station manager's result via radio. If it was deemed airworthy, before landing they'd get a new field pressure altitude reading from the destination manager. Sound reasonable? :dunno:
1.17 Other Information
The following are excerpts from Eastern Air Lines' manual:

"Eastern A i r Lines DC-9 Flight Operations Procedures - Altime t e r s

Altimeters on standard EAL installations are a No. 1(upper) and a No. 2 (lower) for the captain and a No. 1 for the f i r s t officer.

"An altimeter check w i l l be made at station of origin and a t each crew or aircraft change as follows:

1. No. 1 altimeters, set barometric scale to Field Pressure setting (Kollsman) as reported by ground station; check variation of altitude indication from zero.

2. No. 2 altimeter, set barometric scale to most recently reported sea level altimeter setting for the field; check variation of check variation of altitude indication from field elevation."

"In-Range contact w i l l be made directly with the station of intended landing about 15 minutes out and below 18,000 feet in order to obtain:

1. Field pressure (QFE) in feet and millibars, and altimeter setting (QNH) from the ground station.

2. The flight w i l l respond with No. 1 altimeter setting in inches Hg.

3. The ground station w i l l verify altimeter setting and provide fuel information."
​
This was from the crash report of Eastern Flight #212 on 9/11/74 at Charlotte.

dtuuri
 
Last edited:
RotorDude said:
My suspicion is that this unit has been tampered with, since the Kollsman setting indicates "220 feet" low, while the little pointers are reading -870 feet.
Click to expand...
The little pointers read -135 feet, no?

dtuuri
 
I love those old "Flying" magazines. I used to sit down in the bowels of the Suzzallo Library at the UW, in the Science Reading Room. They had bound books of all Flying Magazine from inception.

No wonder I was almost always barely squeaking by! Oh wait!!......girls had some affect as well!
 
dtuuri said:
Here's some insight as to how the altimeters were set to "field pressure" using the Kollsman window to read QFE. Before takeoff, I guess they simply set the altimeter hands to zero and read the "field pressure altitude" off the reference triangles as "xxx feet above/below" the standard datum of 29.92 and cross-checked it with the station manager's result via radio. If it was deemed airworthy, before landing they'd get a new field pressure altitude reading from the destination manager. Sound reasonable? :dunno:
1.17 Other Information
The following are excerpts from Eastern Air Lines' manual:
"Eastern A i r Lines DC-9 Flight Operations Procedures - A l t i m-
-e t e r s (upper) and a No. 2 (lower) for the captain and a No. 1 for the f i r s t officer. Altimeters on standard EAL installations are a No. 1 "An altimeter check w i l l be nude at station of origin and a t each crew or aircraft change as follows:
1. No. 1 altimeters, set barometric scale to Field Pressure setting (Kollsman) as reported by ground station; check variation of altitude indication from zero.
2. No. 2 altimeter, set barometric scale to most recently reported sea level altimeter setting for the field; check variation of check variation of altitude indication from field elevation."​
This was from the crash report of Eastern Flight #212 on 9/11/74 at Charlotte.

dtuuri
Click to expand...

Sounds like #1 altimeter is set to QFE, and #2 to QNH.
Then verify sanity of both.
Not sure about the "altimeter check will be nude at station" reference. :)
Maybe a clue to the accident cause? :hairraise:
 
RotorDude said:
Not sure about the "altimeter check will be nude at station" reference. :)
Click to expand...
Meh. The copy/paste was giving me fits from that old report. Try reading now. It looks like they got the "feet" version for landing as well as millibars (which I suppose they couldn't set?) and then read back the Kollsman reading in inches Hg which the station manager verifed. Ya think?

dtuuri
 
dtuuri said:
The little pointers read -135 feet, no?

dtuuri
Click to expand...

Yes, sorry, I misread that. The little pointers are reading -135 feet, as you say.
But according to the Kollsman window, they should be reading -(30.14-29.92)*1000, which works out to -220 feet. So that's still off by 85 feet, probably outside tolerance (this is a mechanical linkage to the Kollsman setting AFAIK, not connected to the aneroid).
 
dtuuri said:
Meh. The copy/paste was giving me fits from that old report. Try reading now. It looks like they got the "feet" version for landing as well as millibars (which I suppose they couldn't set?) and then read back the Kollsman reading in inches Hg which the station manager verifed. Ya think?

dtuuri
Click to expand...

Yes, sounds right. I am also unclear about the millibars, since I assume their Kollsman was in inches. Maybe they just verified the millibars against a table, as another sanity check. I can imagine that flying non-precision approaches to low minimums (IIRC down to 300' AGL on range-based approaches) with scratchy radios, you'd want to be triple-sure about that setting.
 
dtuuri said:
I dunno, it fits my logic so far. I haven't yet studied the above references and posts, but while I'm at it, here's one from January 1948 Flying Mag.

dtuuri
Click to expand...

What a great article.

It was a bit tough to jump around in that viewer, so in case anybody else wants to read it with less effort, here's a link to download it as one combined PDF:

http://goo.gl/Ua1FCX
 
register@teamandras.com said:
What a great article.

It was a bit tough to jump around in that viewer, so in case anybody else wants to read it with less effort, here's a link to download it as one combined PDF:

http://goo.gl/Ua1FCX
Click to expand...

Thank you so much for that! :) I'll savor every word later today. I can see where the principles involved may be somewhat lost on pilots these days. This looks like a terrific review. For instance, I had to puzzle out why setting the hands to zero would render ambient pressure. Probably hadn't thought about it in several decades.

dtuuri
 
dtuuri said:
Thank you so much for that! :) I'll savor every word later today. I can see where the principles involved may be somewhat lost on pilots these days. This looks like a terrific review. For instance, I had to puzzle out why setting the hands to zero would render ambient pressure. Probably hadn't thought about it in several decades.

dtuuri
Click to expand...

This trick would only work at near-SL fields, and not in flight, since AFAIK the Kollsman correction is typically limited to +/- 1000' or so.
 
Last edited:
You must log in or register to reply here.
Back
Top