Transcript Document
U.S. AIR FORCE AUXILIARY
ES Aircrew 2009 Update Training
US National Grid Awareness
Lt. Col. Stan Kegel Minnesota Wing April 2009
Agenda
Our goal today: – Become familiar with the US National Grid (USNG) In short, what is it?
How does it relate to other common grid and coordinate systems?
In what situations does it work well?
Where did this requirement come from?
Who must use it and when?
What complications exist? This course is only and introduction and is not intended to fully teach the ability to use USNG in navigation
What is USNG?
A GRID System – – – – – Each numbered grid describes a square area (not a point like Lat/Long) Supports grids of many scales, from 100 km down to 1 meter (or, theoretically even smaller) Flat, square coordinate system Seamless with respect to political boundaries Truncated (abbreviated) form can be used often (when context tells us what part of the country is relevant) Based on UTM (Universal Transverse Mercator) Coordinates – USGS topographic map “Grid North” refers to the UTM (and USNG) coordinate system
USNG & MGRS
MGRS – Military Grid Reference System – NATO Standard USNG is nearly the same as MGRS – – – Declared a separate standard so each can be free to change to meet the needs of its audience in the future Right now completely equivalent if the NAD83/WGS84 datum is used Differences in notation if other datums are used One of its benefits of the adoption of the USNG standard is that military personnel essentially already know it (and they are often acting in support of catastrophic incidents)
UTM Basics – Big Pictures
UTM “zones” every 6 degrees of longitude Latitude band every 8 degrees of latitude “Grid zone designation” (GZD) – A combination of zone and latitude band Each “grid zone” has its own map projection.
– Most of Minnesota is in grid zone
15T U
48°N
T
40°N
S
32°N
R UTM/USNG Grid Zone Designations
126° 120° 114° 108° 102° 96° 90° 84° 78° 72° 66° 24°N
10 11 12
08/27/98
13 14 15 16 17 18 19
UTM Basics – Coordinates
A Northern Hemisphere UTM Location is given as… – – – Grid Zone “Easting” Measurement (in meters) east/west of the central meridian of the zone The central meridian is given a value of 500,000 meters to avoid negative numbers Numbers greater than 500,000 are east of central meridian “Northing” Measurement (in meters) north of the equator Example: 15 511196 4982565 (Point on St Paul, Lake Elmo Airport)
USNG Grids – Differences from UTM
Grid zones broken up into “100,000 m Squares” – Caveat: On the edges of the Grid zone, the 100,000 m squares are not square.
Each “Square” is given a two letter “ID” The IDs are arranged so that the same ID occurs only a few times in the country and always a long way away – This allows for “truncated” grid references (i.e. omitting the GZD and the 100,000 m Square ID) The use of 100,000 m Squares means that we don’t need the first 2 digits of the UTM Northing and the 1 st digit of the UTM Easting, so these digits are omitted from USNG grid coordinates
USNG Grid Coordinates
In full form, given as… – – – Grid Zone Designation 100,000 m Square ID Easting and Northing numbers Always with same number of digits for each part The number of digits defines the grid size/precision – – – – Four digits: Six digits: Eight digits: Ten digits: 23 06 233 065 2337 0651 23371 06519 Locating a point within a 1,000-m square Locating a point within a 100-m square (football field size) Locating a point within a 10-m square (modest size home) Locating a point within a 1-m square (parking space size) Example: 15T WK 11196 82565 (Point on St Paul Lake Elmo Airport) Truncated form omits GZD and 100,000 m Square ID
Comparing Coordinates
St Paul Lake Elmo Airport
– UTM : 15 511196 4982565 – – USNG : Lat/Long: 15T WK 11196 82565 44 59.78’ N 92 51.48’ W
St Paul Downtown Airport
– UTM : 15 494689 4976117 – – USNG : Lat/Long: 15T VK 94689 76117 44 56.30’ N 93 04.03’ W
USNG – Minnesota
USNG – Big Picture View
Strengths
For terrestrial navigation – Not for aeronautical/maritime use Works best over relatively small areas – The land can be modeled reasonably as a flat area when working in small areas
Who is driving this, and why?
NSARC – National SAR Committee (DOD, DHS, et. al.) – – Addressing Katrina SAR Issues: How do SAR Responders navigate when landmarks are destroyed Need for a grid system for SAR planning (resource deconfliction, etc.) Practical difficulties using Latitude and Longitude for terrestrial small area navigation.
USNG: What scenarios are driving this?
“Catastrophic Incident” SAR – Think Hurricane Katrina – Think 35W Bridge Collapse
Catastrophic Incident SAR NSARC Georeferencing Matrix
Georeference System User Land SAR Responders [2] Aeronautical SAR Responders [3] Air Space De-confliction [4] Land SAR Responder/Aeronautical SAR Responder Interface [5] Incident Command: Air SAR Coordination Land SAR Coordination Area organization and accountability [6] USNG Primary
Secondary N/A
Primary
Secondary
Primary
Secondary
Latitude/Longitude DD-MM.mmm [1]
Secondary
Primary Primary
Secondary
Primary
Secondary Tertiary
GARS
N/A Tertiary N/A N/A N/A N/A
Primary
NSARC Georeferencing Matrix Footnotes
1.
2.
3.
During CIS operations, Lat/Long will be in one standard format:
DD-MM.mmm
Land SAR Responders must use USNG; however a good familiarity with lat/long is necessary to ensure effective interface between land and air SAR responders Air SAR Responders will use Lat/Long
NSARC Georeferencing Matrix Footnotes
4.
5.
6.
Air space deconfliction: only in Lat/Long Air SAR Responders working with land SAR responders have primary responsibility of coordinating SAR using USNG Both need to know USNG and Lat/Long GARS (Global Area Reference System): used for CIS response leadership situational awareness
What about Lat/Long?
Couldn’t a grid system be built on that?
Lat/Long: – Great system for larger area navigation but… Distances not easy to figure out – – How far is 1 degree of longitude?
Shorter distances get even more awkward. (How far is 0.1 minutes of longitude?) Difficult to accurately plot positions (or grids) based on Lat/Long with using a topo map In small areas, it is easier to think in terms of linear distances (feet, meters, kilometers, miles, etc.) – Example: Go 100 m east, then 200 m north
Would a scrolling-map GPS device solve the problem?
GPS devices are great for providing position info … in a variety of possible display formats Lat/Long (DD MM.mmm, DD MM SS.s, …) UTM USNG etc.
They are horrible maps, however
Complications to expect
UTM/USNG awkward at and near grid zone boundaries