Intersection Station elevation question

[+LSUFan]

As usual, when Jim/Holograph posts his monthly statistics, after I look at the maps, I seem to always end up looking at the extreme stations while on his site.

 

I keep looking at the highest elevation benchmarks for Louisiana, and noticed something today that I haven't really studied........so I brought my questions to the experts here.

 

The highest benchmark in LA is the Gentry LookoutTower CQ2886 and the point intersected is the TOP CENTER OF A 6-FOOT SQUARE CABIN SUPPORTED BY A 4-LEGGED STEEL STRUCTURE WITH AN OVERALL

HEIGHT OF 80 FEET. It's scaled height is 512 feet. It has adjusted horizontal coordinates.

 

Now the second highest point is Gentry triangulation station CQ2887

This station is down on the ground near the Gentry LOT. However it's elevation (vertcon)is 511 feet....or one foot less than the 80 foot high Gentry LOT

 

In obtaining the elevation for the Gentry LOT, would they have just measured the ground level that the LOT sits on? I don't guess I have enough experience with intersection stations to have ever really looked at how the elevation information is derived for them. I just thought it was real curious the there was only 1 foot difference between the two........even though one of the points is 80+ feet above the other.

 

I'm just guessing that difference is because the LOT has scaled elevation numbers (which just coincidentally put it within a foot heighth of the other), but would welcome any guru knowledge about this. Thanks

Edited September 14, 2011 by LSUFan

[southpawaz]

Per the data sheet:

 

CQ2886.The orthometric height was scaled from a topographic map.

[+LSUFan]

Per the data sheet:

 

CQ2886.The orthometric height was scaled from a topographic map.

 

Is it safe to assume they took the elevation of the base of the LOT on the topo map, and didn't add the 80 foot to it......and/or does the term orthometric tie it to the surface of the earth?

 

Thanks

[southpawaz]

Yes I think it's safe to say that they did not take the height of the tower into account. Looking at the topo map I would put the height of the ground at the tower somewhere between 510 and 520 feet (not used to seeing 10' contour lines!).

[+LSUFan]

Thanks southpawaz. I am 99.9% percent sure this LOT is not there anymore. It is almost across the road from where you park to access the trail to Mount Driskill (the highest point in LA). As many times as I have went up Driskill with geocaching friends, I believe I would have noticed a fire tower nearby. I think there are just cell phone towers there now, but will definitely make sure the next go around. I think I looked one time, but may be confusing this with another one.

 

I might be able to search for the Gentry triangulation station though, depending on if there is access. It's probably fenced off.

Edited September 15, 2011 by LSUFan

[+frex3wv]

I can't really add much to this specifically, however a good look in the area will make it pretty clear if the structure still stands! Replaced by modern communication towers??? I wouldn't be suprised. I went looking for an old airway beacon and found modern towers in the place where it once stood. I was bummed - BUT.... it made the elusive and rare one I DID find THAT much more meaningful to me!

[+EdrickV]

I can't really add much to this specifically, however a good look in the area will make it pretty clear if the structure still stands! Replaced by modern communication towers??? I wouldn't be suprised. I went looking for an old airway beacon and found modern towers in the place where it once stood. I was bummed - BUT.... it made the elusive and rare one I DID find THAT much more meaningful to me!

 

Supposedly there are only 14-19 airway beacons still in existence, and they're in western Montana.

 

http://en.wikipedia.org/wiki/Airway_beacon

http://www.mdt.mt.gov/aviation/beacons.shtml

[+frex3wv]

EdrickV - I know we are not trying to hijack this thread - but just to be careful = this is the last post by me on aiway beacons on THIS thread - BUT - the article you posted said 14 were still operational. You CAN find decommissioned ones still standing ( i did ) but they are few and far between. (looked for 2 others in addition to the one I found - they were gone!)

[kayakbird]

 

Supposedly there are only 14-19 airway beacons still in existence, and they're in western Montana.

 

 

I used some of these to stay out of the icing layers when I was a Freight Dog flying canceled checks out of HLN in 1988-1997.

 

The below info was provided by Montana Aeronautics a couple of years ago and I logged a few before I quit doing spires (except for DEVILS TOWER TOP CENTER). Tried to format the below in neat columns, but the site compressed it again. Contact me off forum if you would like an Excel file.

 

kayakbird

 

AIRWAY, OBSTRUCTION AND AIRPORT BEACONS

OPERATED BY MONTANA AERONAUTICS DIVISION

 

BEACON GARMIN NAME LAT DDMMSS LONG DDDMMSS HEIGHT

Alberton ALBRTN 47° 1.5’ 470130 114° 29’ 1142900 55 feet

Avon AVON 46° 33.5’ 463330 112° 38’ 1123800 90 feet

Bonita B0NTIA 46° 34.5’ 463430 113° 37’ 1133700 55 feet

Bozeman Pass BZN PASS 45° 39’ 453900 110° 49’ 1194900 10 feet

Canyon Resort CNY RESORT 45° 4.5’ 450530 112° 48.5’ 1124830 90 feet

Hardy HARDY 47° 11’ 471100 111° 48’ 1114800 90 feet

Homestake Pass HMSTK PSS 45° 53.5’ 455330 112° 25’ 1122500 12 feet

McDonald Pass MAC PASS 46° 33’ 463300 112° 18.5’ 1121830 90 feet

Monida Pass MONIDA PSS 44° 33.5’ 443330 112° 22’ 1122200 55 feet

Mullen Pass MULLN PASS 47° 28’ 472800 115° 40’ 1154000 55 feet

Silver Bow SLVR BOW 46° 4’ 460400 112° 42’ 1124200 55 feet

Spokane SP0KANE 46° 32.0’ 463200 111° 43.0’ 1114300 55 feet

Stoney Point STONEY PT 46° 51.2’ 465112 111° 58’ 1115800 55 feet

Strawberry STR BERRY 45° 58’ 455800 111° 20.2’ 1112012 55 feet

St. Regis ST REGIS 47° 16.5’ 471630 115° 1.5’ 1150130 55 feet

University Mountain U MOUNTAIN 46° 51.3’ 465118 113° 56.0’ 1135600 55 feet

Whitetail WHITETAIL 46° 5.2’ 460512 112° 9.0’ 1120900 25 feet

Wolf Creek WOLF CREEK 47° 1.5’ 470130 111° 58’ 1115800 55 feet

Dell Arprt DELL APRT 44° 44’ 444400 112° 44’ 1124400 55 feet

Lncln Arprt LNCLN APRT 46° 57’ 465700 112° 39’ 1123900 90 feet

[TillaMurphs]

 

I used some of these to stay out of the icing layers when I was a Freight Dog flying canceled checks out of HLN in 1988-1997.

 

 

Holy interspecies transformation Batman!

 

You used to be a dog and now you are a bird?

[kayakbird]

You used to be a dog and now you are a bird?

 

Use the reciprocal. And Yup, my Dad figured I was headed the one way long before the brothers made a million off the combination and I got a few non-combat hours in one.

 

Thanks for getting me away from my far out Lat/Long file for a few minutes - even tho it is great fun to DSWORLD the correction after using same to pin the DS #'s and then adding the AS FOUND position. 4.5% are greater than 6 seconds out and another 14.5% greater than two seconds.

MEL

[+LSUFan]

OK, all this talk about old airway beacons got me curious as I have seen some datasheets for them before in my local area. Normally I don't do many intersection stations, but the history of these was too tempting.

 

I used GSAK to filter them out and it appears there are about 5 of these old airmail route ones still listed in the NGS database for LA, and they are all on the Ft.Worth to Atlanta route, which passes right over me.

 

I used google earth/maps to see if I could see any structures but couldn't decide on what I was viewing on a few of them. I happened to be near three of them today........and you just know I had to take a personal gander (wouldn't you?).

 

None of the three were there (and I didn't really expect them to be). There is one that maybe is there. It is further west, but I will be that way later this week to check, and the power squadron submitted a found recovery report on it in 2003. The satellite view and street view show a three-legged tower, so this may not be a true one.

 

I now need to say it's all frex3wv's and EdrickV's fault.

Edited September 19, 2011 by LSUFan

[+frex3wv]

Since this IS LSU's thread - I feel by responding I am not hijacking - so.....

 

the one I found is my fav. find of all time - KEEP LOOKING! Few things are more rare to find.

 

You will notice no disk associated with these - the intersection is normally the light at the top.

 

Here is something else to consider when you look for these......... 1) before them they used BONFIRES set by the public to fly at night - so these were HUGE in the air navigation world 2) If you don't find the tower - you MAY find a concrete arrow - also very rare and a HUGE find. 3) if the location is adjusted - you should be easily able to tell if you have found it - walk to where your gps tells you to go - either it is there, gone, or replaced by a clearly newer tower.

 

Hope this helps.......... and if you find one.........................

[+LSUFan]

- walk to where your gps tells you to go - either it is there, gone, or replaced by a clearly newer tower.

 

Hope this helps.......... and if you find one.........................

 

Ok, I am firmly placing the blame for my obsession for finding one of these on you now, frex3wv.

 

When I look at CQ3244 on google maps, I can see a four-legged tower, and it looks real similar to the ones in the history links provided. However, there also seems to be more mast above the platform, which I guess could have been added later. I will be over that way in a few days and take a looksee. It is all fenced in, so I won't be able to get but so close.

 

[+EdrickV]

I looked airway beacons up on Wikipedia not too long ago because I'd passed by an area where one was supposed to be in a car and there wasn't any obvious sign of it. (Did not actually go looking for it, and I'm pretty sure that if there was anything left of it, it would be on private property and probably a ruin since the area where it should have been is full of trees now.

 

And I guess I should have said that (aside from those Montana ones) they were all supposedly shut down, which of course doesn't mean they were destroyed.

 

Edit: Missed a bunch of posts while I was in the middle of making mine, and getting sidetracked. That picture does look like the style tower they used, I'm thinking after it was shut down maybe it was changed into something else. One thing I'd considered is that maybe it was also a Radio Range station, but if so the other towers apparently are gone. The square fenced in area kinda looks like pictures in Wikipedia. But I don't know if any of those stations would have been used for both. Also not sure if the building is original or not.

 

If you go out there and there happens to be a big arrow attached to the tower, then that would be a good indicator that it's likely the original tower. (Arrow doesn't show in the Wikipedia version of the diagram, but somewhere I saw a larger one that showed it.)

Edited September 20, 2011 by EdrickV

[AZcachemeister]

ES1047 is still there!

[+frex3wv]

I gladly accept your blame - you will be glad we encouraged you when you DO find one.

 

My suggestion is to do a forums search on airway and you will find ALOT to read.........

Edited September 20, 2011 by frex3wv

[andylphoto]

Per the data sheet:

 

CQ2886.The orthometric height was scaled from a topographic map.

 

Is it safe to assume they took the elevation of the base of the LOT on the topo map, and didn't add the 80 foot to it......and/or does the term orthometric tie it to the surface of the earth?

 

Thanks

 

It's probably safe to assume on this station, given the replies (I didn't look.) However, don't necessarily assume this is a safe assumption for every intersection station.

 

In Michigan's top 10 by elevation, there are several towers. Highest stations number 7 and 8 are a (now destroyed) lookout tower and a nearby triangulation station disk, (RL1514 and RL1515) both published with identical altitudes, at ground level. Same with stations number 9 and 10 (RL1652 and RL1653).

 

However, highest station number 2 is a different story. It is a TV mast, AH5424. It also contains the same line:

 

AH5424.The orthometric height was scaled from a topographic map.

 

The scaled elevation is 1886 feet, but the topo map shows the tower positioned near the 750 foot contour. The ASR data for this particular tower shows the structure height at 343 meters, with the overall tower height above sea level at 573 meters, or 1880 feet.

 

Not sure where the 1886 came from, but it's not ground level in any case.

Edited October 12, 2011 by andylphoto