Chapter 18, Annex O MAGNETIC DECLINATION WORKSHEET: ANSWER KEY

Grid Magnetic Angle + [(Current Year - Year of Declination Information) × (Annual Change)] = Current Declination

Question 1:

Grid Magnetic Angle:

Current Year

Year of Declination Information:

Annual Change:

10° 46'

2011

1988

decreasing 5.2'

10° 46' + [(2011 - 1988) × (-5.2')] = Current Declination

10° 46' + [(23) × (-5.2')] = Current Declination

10° 46' + [-119.6'] = Current Declination

10° 46' - 119.6' = Current Declination

9° 106' - 119.6' = Current Declination

8° 166' - 119.6' = Current Declination

8° 46.4' = Current Declination

Magnetic declination is 8° 46.4' east.

Question 2:

Grid Magnetic Angle:

Current Year:

Year of Declination Information:

Annual Change:

11° 2'

2014

1995

increasing 3.8'

11° 2' + [(2014 - 1995) × (+3.8')] = Current Declination

11° 2' + [(19) × (+3.8')] = Current Declination

11° 2' + [+72.2'] = Current Declination

11° 2' + 72.2' = Current Declination

11° 74.2' = Current Declination

12° 14.2' = Current Declination

Magnetic declination is 12° 14.2' east.

Question 3:

Grid Magnetic Angle:

Current Year:

Year of Declination Information:

Annual Change:

18° 43'

2013

1986

decreasing 6.5'

18° 43' + [(2013 - 1986) × (-6.5')] = Current Declination

18° 43' + [(27) × (-6.5')] = Current Declination

18° 43' + [-175.5'] = Current Declination

18° 43' - 175.5' = Current Declination

17° 103' - 175.5' = Current Declination

16° 163' - 175.5' = Current Declination

15° 223' - 175.5' = Current Declination

15° 47.5' = Current Declination

Magnetic declination is 15° 47.5' west.

Question 4:

Grid Magnetic Angle:

Current Year:

Year of Declination Information:

Annual Change:

9° 14'

2018

1999

increasing 4.1'

9° 14' + [(2018 - 1999) × (+4.1')] = Current Declination

9° 14' + [(19) × (+4.1')] = Current Declination

9° 14' + [+77.6'] = Current Declination

9° 14' + 77.6' = Current Declination

9° 91.9' = Current Declination

10° 31.9' = Current Declination

Magnetic declination is 10° 31.9' west.

Question 5:

Grid Magnetic Angle:

Current Year:

Year of Declination Information:

Annual Change:

19° 35'

2016

1981

decreasing 5.4'

19° 35' + [(2016 - 1981) × (-5.4')] = Current Declination

19° 35' + [(35) × (-5.4')] = Current Declination

19° 35' + [-189'] = Current Declination

19° 35' - 189' = Current Declination

18° 95' - 189' = Current Declination

17° 155' - 189' = Current Declination

16° 215' - 189' = Current Declination

16° 26' = Current Declination

Magnetic declination is 16° 26' west.

Question 6:

Grid Magnetic Angle:

Current Year:

Year of Declination Information:

Annual Change:

18° 22'

2010

1976

increasing 4.7'

18° 22' + [(2010 - 1976) × (+4.7')] = Current Declination

18° 22' + [(34) × (+4.7')] = Current Declination

18° 22' + [+159.8] = Current Declination

18° 22' + 159.8' = Current Declination

18° 181.8' = Current Declination

19° 121.8' = Current Declination

20° 61.8' = Current Declination

21° 1.8' = Current Declination

Magnetic declination is 21° 1.8' west.

Question 7:

Grid Magnetic Angle:

Current Year:

Year of Declination Information:

Annual Change:

12° 34'

2020

1991

increasing 1.2'

12° 34' + [(2020 - 1991) × (+1.2')] = Current Declination

12° 34' + [(29) × (+1.2')] = Current Declination

12° 34' + [+34.8'] = Current Declination

12° 34' + 34.8' = Current Declination

12° 68.8' = Current Declination

13° 8.8' = Current Declination

Magnetic declination is 13° 8.8' east.

Question 8:

Grid Magnetic Angle:

Current Year:

Year of Declination Information:

Annual Change:

13° 21'

2017

1994

decreasing 2.9'

13° 21' + [(2017 - 1994) × (-2.9')] = Current Declination

13° 21' + [(23) × (-2.9')] = Current Declination

13° 21' + [-66.7'] = Current Declination

13° 21' - 66.7' = Current Declination

12° 81' - 66.7' = Current Declination

12° 14.3' = Current Declination

Magnetic declination is 12° 14.3' east.

Question 9:

Grid Magnetic Angle:

Current Year:

Year of Declination Information:

Annual Change:

3° 16'

2012

1980

decreasing 6.2'

3° 16' + [(2012 - 1980) × (-6.2')] = Current Declination

3° 16' + [(32) × (-6.2')] = Current Declination

3° 16' + [-198.4'] = Current Declination

3° 16' - 198.4' = Current Declination

2° 76' - 198.4' = Current Declination

1° 136' - 198.4' = Current Declination

196' - 198.4' = Current Declination

-2.4' = Current Declination

Since the current declination calculated has a negative value, the east declination, as shown on the declination diagram, becomes a west declination.

Magnetic declination is 2.4' west.

Question 10:

Grid Magnetic Angle:

Current Year:

Year of Declination Information:

Annual Change:

4° 27'

2019

1977

increasing 2.2'

4° 27' + [(2019 - 1977) × (+2.2')] = Current Declination

4° 27' + [(42) × (+2.2')] = Current Declination

4° 27' + [+92.4'] = Current Declination

4° 27' + 92.4' = Current Declination

4° 119.4' = Current Declination

5° 59.4' = Current Declination

Magnetic declination is 5° 59.4' east.

Question 11:

Grid Magnetic Angle:

Current Year:

Year of Declination Information:

Annual Change:

7° 7'

2021

1992

increasing 5.5'

7° 7' + [(2021 - 1992) × (+5.5')] = Current Declination

7° 7' + [(29) × (+5.5')] = Current Declination

7° 7' + [+159.5'] = Current Declination

7° 7' + 159.5' = Current Declination

7° 166.5' = Current Declination

8° 106.5' = Current Declination

9° 46.5' = Current Declination

Magnetic declination is 9° 46.5' west.

Question 12:

Grid Magnetic Angle:

Current Year:

Year of Declination Information:

Annual Change:

9° 36'

2015

1983

decreasing 3.3'

9° 36' + [(2015 - 1983) × (-3.3')] = Current Declination

9° 36' + [(32) × (-3.3')] = Current Declination

9° 36' + [-105.6'] = Current Declination

9° 36' - 105.6' = Current Declination

8° 96' - 105.6' = Current Declination

7° 156' - 105.6' = Current Declination

7° 50.4' = Current Declination

Magnetic declination is 7° 50.4' west.