World Affairs Board - View Single Post - USS New Jersey in Lebanon Channeling Thread

Shipwreck · 03-20-2008, 06:43 AM

Quote:

Dispersion Of Shells In Lebanon

This posting is in response to Dr. Elder's comments about NEW JERSEY's accuracy buried in a posting deep in what has turned out to be the most active posting for sometime.

As Dr. Elder has correctly identified they were significant degradation to some of the powder lots used by 'Big Jay'. This resulted in extreme variations in Initial Velocities (IVs) which subsequently yielded "Shot Groups" similar to a shotgun pattern.

However, all powder lots were not seriously effected and there were NGF missions that resulted in "Target Destroyed". I believe AP gave us the story of somebody leaving for a cup of coffee that resulted in a fire mission which inadvertently resulted in destroying an enemy target that was supposed to "off limits". What a shame.

The purpose of this posting is to inform the "community" of a little known fact that I became aware of last year that is extremely relevant.

While attending a National Imagery and Mapping Agency (NIMA) Mapping, Charting, and Geodesy (MC&G) course, the instructor informed me of the various DATUMS and MAP PROJECTION SYSTEMS that are in place, that are used to map and navigate the earth. He specifically addressed the REQUIREMENT that before doing anything, as a matter of Standard Operating Procedure (SOP) that all personnel, when working with more than one person, you ensure that everybody is working off the same Sheet of music. In this case he is referring to the same MAP SHEET.

Specifically, in Lebanon, while "Calling-for-Fire", the ground units were issued maps of the Local Area. These maps used the NORTH AFRICAN MAP PROJECTION SYSTEM. Because it only maps a small sample of the earth, it is extremely accurate. The NEW JERSEY was using either a NORTH AMERICAN MAP PROJECTION SYSTEM or the WORLD GEODETIC SYSTEM - 72 (he didn't specify which).

Analysis of the difference, in distance, of the exact same coordinate, between the two maps, using two entirely different mapping methodologies was and still is 800 METERS!!!!!!!

This, in conjunction with powder inconsistencies, explains much since analysis of most of NEW JERSEY's NGFS missions were UNOBSERVED and UNADJUSTED.

GOD Bless the Vets!

Tracy A. Ralphs
Program Director, USNFSA

Link

The response I posted in another thread :

Quote:

Originally Posted by Shipwreck

2. Regardless the validity of Tracy Ralphs' *Common Map Sheet* theory, the average shift between WGS (World Geodetic System) and local geodetic datums, if unaccounted for, would only negatively affect accuracy (i.e. difference between MPI and desired aimpoint) and has NO impact whatsoever on precision (i.e. dispersion of individual shots vs MPI).

IOW, the suggested misuse of datums and grids has NOTHING to do with the excessive dispersion observed with USS New Jersey's gunnery off Beirut.

3. In Lebanon, USS New Jersey indeed used WGS-72 (World Geodetic System 1972) coordinates, while USMC (and US Army ) personnel ashore used 1:50,000 topo maps on ED-50 (European Datum 1950) coordinates. The average shift between WGS-72 and ED-50 is around 175 meters for continental Europe and 200 meters for Lebanon (+ Iraq, Israel, Jordan, Kuwait, Lebanon, Saudi Arabia, Syria).

IOW, even if unaccounted for, the difference in geodetic datums for Lebanon(WGS-72 vs ED-50) DOES NOT translate into a difference of 800 meters as Tracy Ralphs suggests.

4. Since multiple datums are a frequent situation on the battlefield, it is a key priority for the NGLO to make sure that these datums are not being misused and differences are properly accounted for.

While there may have been some *confusion* at the beginning of USS New Jersey's deployment off Beirut (possibly affecting her first 16-inch mission on 14 December 1983), the suggested theory by which differences in datums remained unaccounted for until 8 February 1984 (i.e. the day when the battleship fired 288 x 16-inch shells and problems with excessive dispersion became obvious) is PURE FANTASY.

Besides USS New Jersey, it's worth noting that several cruisers, destroyers and frigates provided accurate and effective NGFS with their 5-inch *pop-guns* on many occasions during our intervention in Lebanon.