John Hitchcock's Navigation Notes

John Hitchcock's Navigation Notes

Notes kept by John during his navigation training.

One booklet

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MHitchcockJS740899-170926-20

No. 1. SQDN,
‘A’ FLIGHT.

Form 619.

[underlined 740899 SGT. J.S. HITCHCOCK [/underlined]

[underlined] Navigation [underlined]

ROYAL AIR FORCE

Small Notebook for use in Schools.

T.4154. Wt. IIIII. 2/39.

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[underlined] Navigation. [/underlined]

Leeds [deleted] 1°38’W [/deleted] 53°47’ N 01°33’ W
Gt. Ormes Head 53°22’ N 03°55’ W
Heligoland 54°12’ N 08°06’ E
Luxembourg 49°37’ N 06°08’ E
Dunkerque 51°03’ N 02°25’ E
Kiel 54°20’ N 10°10’ E
Pointe Haute Bank 50°23’ N 01°34’ E

Outer Sabber

Stuttgart
Bee’s Head.

[Underlined] Change of Lat & Long. [/underlined]

[underlined]Ch of Lat.[/underlined] is arc of merid. Intercepted by //s of lat. through the two places. If going from N – S ch. is S, if S-N ch. is N.

[underlined] Ch. of Long. [/underlined] is smaller arc of equator intercepted between merids. of the two places named E or W.

For the same names, subtract to find change.
For different names, add.

[deleted] Ch [/deleted] [underlined] Example. [/underlined] Ch. Lat. = 14°57’ S, [inserted] ch. Long [/inserted] 55°50’ E.
Ch. Lat = 20°42’ N, 29°22’ E
Ch. Lat. = 14°30’ S 344°57’ W (15°03’ E)

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One point where rule does not apply is where ch. of long is greater than 180°.

Ch. of long = 320° W [deleted letters] but with smaller arc it = 360°- 320° W = 40° E.

FROM 45°30’ S 40°20’ W
TO 60°27’ S 15°30’ E
Ch. Lat 14°57’ S Ch. Long. 55°50’ E

FROM 30°33’ N 30°42’ W
TO 51°15’ N 01°20’ W
Ch. Lat. 20°42’ N Ch. Long. 29°22’ E.

From 10°17’ N 168°11’ E
TO 04°13’ S 176°46’ W
14°30’ S 15°03’ E

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[underlined] Variation. [/underlined]

[underlined] Method of telling [/underlined]

1. Isogonals, lines joining points of similar variations.
2. Statement in words
3. Compass rose
4. Marginal diagram

Estimate variation along the normal between the two isogonal. [deleted letter] Connect for date.

Variation changes at different parts of globe. Also changes at same place with time.

West is a – variation, East is a + variation.

[deleted] Time [/deleted] [underlined] Trim [/underlined] [underlined] Var. [/underlined] [underlined] Mag. [/underlined]

182° 12° E 170°
312° -06° (W) 318°
130° 13° W 143
89° 09° W 098°

[underlined] Deviation [/underlined] is [symbol] [deleted] to [/deleted] between magnetic merid & axis of compass needle. East +, West -.

N.B. Never say dev. [underlined] in [/underlined] a compass but [underlined] at [/underlined] a compass. Compass error is also a misnomer since the compass may be working perfectly. It is merely affected by external fields. Compass error = Algebraic sum of V + D.

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The main principles

1.Dev. in aircraft changes with course. 2. Magnetic fields produced in a soft iron bar affect the compass. All bearings written in groups of 3 figures followed by M, T, or C.

[a] T. [b] V. [c] M. [d] V. [e] C.
[a] 176° [b] 13°W [c] 189° [symbol] [d] [deleted number] 2° E [symbol] [e] 187°
[a] 254° [b] 9° [symbol] [c] 263° [d] [deleted number] 3° E [symbol] [e] 260°
[a] 037° [b] +06° [c] 031° [symbol] [d] 1° W [e] 032° [symbol]
[a] 008° [symbol] [b] 15° W [c] [deleted] 15° W [/deleted] 23° [symbol] [d] 3° E [e] 020°
[a] 323° [symbol] [b] +11° [c] 321° [d] +4° [e] 317° [symbol]
[a] 358° [b] 12° W [c] 010° [symbol] [d] 2° W [e] 012° [symbol]

[Diagrams]

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On a course of 170° the bearing of an object is 40° by bearing compass. The true bearing is 060° & the variation is 10° E. The course is 185° by pilots compass. Field deviation at pilots compass.

True bearing = 060
Variation = 10° E.
Magnetic = 050°
Deviation at B.C. = 10° E.

Course at Bearing Comp. = 170°
Mag. Course = 180°
Pilots Compass = 185°
Dev. at P.C = 005° W.

The bearing of an object can in no way affect the compass needle. What does affect the needle is the course of the aircraft. [Symbol] to all compass bearings we must apply the deviation for the course & not look at the deviation against the particular bearing.

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[underlined] Problems[/underlined]

[Diagrams]

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[Diagrams]

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[Diagrams]

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[Diagrams]

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[Diagrams]

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On [underlined] Navigation Maps [/underlined] [inserted] meridians [/inserted] one st. lines conveying towards the related poles. //s of latitude are curves concave & // towards relates poles.

On [underlined] mercators [/underlined] meridians are // equidistant st. lines, //s of latitude are // at lines but are [underlined] not [/underlined] equidistant.

[underlined] Bearings, Courses & Tracks. [/underlined] Section 6

[underlined] Great Circle Bearings [/underlined] or [indecipherable word] of an object is the [symbol] at the observer between his median & the grid circle joining his position to the object.

[deleted letter] [underlined] Visual [/underlined] bearings & wireless D.F. bearings when connected for quadrantal error & coastal refraction are great circle bearings.

[underlined] Truncational [/underlined] or [/underlined] rhumb [/underlined] line nearing of an object is the [symbol] between the meridian through the observer & the rhumb lines joining his position to the object. Only on mercators projection is a rhumb line laid down accurately as a straight line. [deleted letters]

[underlined] Course of an aircraft [/underlined] is the [symbol] in the horizontal plane between the meridian through the aircraft & the [deleted] effective [/deleted] fore & aft [deleted] the [/deleted] axis (abbrev is [symbol].)

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[underlined] Track [/underlined] of an aircraft is the [symbol] in the hori. plane between the meridian through the aircraft & a line representing the actual path of the aircraft relative to ground.

Bearings, courses & tracks should be taken from maps & charts with reference to the true or geographical meridian, but for obvious reasons the readings in a plane are referred to one of the two compasses which the plane usually carries.

[underlined] Measurement of Lat & Long [/underlined]

[underlined] Long [/underlined]

[underlined] Kolberg [/underlined] Top scale 15°33’ E, 15°34’ E
// rule. Bottom Scale 15°33’ E, 15°36’ E
Always measured from nearest meridian to the nearest scale
Wind Straight edge, 15°35’ E. arrange st. edge to pass thro’ place & reads same value for long. on both scales.

[underlined] Lat [/underlined]

On [indecipherable word] the same method can be used for measuring lat. & long. i.e. as above. On other maps use compass for measuring latitude.

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Bearing, courses, & Track must be reported in group of 3 figures followed by (T), (M) or (C).

{underlined] Section 7 Maps [/underlined]
Navigation maps are based on same form of conic [deleted] conical [/deleted] projection.

[underlined] Scale [/underlined] of maps may be individual in one of the following ways.

[circled 1] [underlined] Representative fraction [/underlined] (R.F.)

This is the ratio of the distance between two points on the map to the distance on the surface of the earth between the two actional positions R.F. = map/ground

e.g. a 1 inch map RF = 1”/63360”
1/4 inch map RF = 1/4 / 63360 = 1/253,440

N.B In the R.F the numerator & denominator must be of the same units & the numerator must be units.

[circled 2] [underlined] Scale Lines [/underlined] are printed in the margin of maps & are usually 3 of [indecipherable word] showing [circled a] Statute miles, [circled b], Nautical miles [circled c] Kilometres

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[circled 3] Statement in words
e.g. “Scale of 10 Statute miles to one inch = 1/633600

On any aviation map the scale can be taken as accurate at any part of the sheet & in any direction, except mercators.

[underlined] Methods of showing relief [underlined]

1. Contours & form lines
2. Layer tinting
3. Spot heights
4. [indecipherable word]
5. Hill shading.

A contour is a line running along surface of earth at some height above mean sea level throughout its length. They are determined by accurate survey.

Form lines are approximate contours usually only partly surveys & filled in by visual estimation, hence they are not entirely reliable.

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[inserted] Always interpret for the course, & apply it to the bearing. [underlined] Never [/underlined] [indecipherable words] bearing. [/inserted]

[underlined] Problems. [underlined]

1. V.9° W. Course by pilots C. 165’ [deleted] D.U.F.C 2° E [/deleted]
Dev at Pilots C 135° 2° E
180° 1° W
225° 2 W

Bearing of Lighthouse by observers compass at same instant is 193°
Dev. at observers compass
135° 0°
180° 3° W
225° 2 E

[circled a] Find T course = 156°
[circled b] Find T bearing = 182°

2. [circled a] Deviation at observers compass = 4° E
Deviation mag. bearing = 078°
Deviation true bearing = 067°
[circled b] Dev at observers compass = 4° E
[symbol] magnetic = 316°

[deleted] True bearing = [/deleted]

[symbol] Dev at pilots compass = 321° - 316° = 5° W
[deleted] [symbol] magnetic at pilots compass = 316° [/deleted]

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[underlined] Maps [/underlined]

[underlined] Vertical interview [/underlined] is the difference in altitude between adjacent contours. The plan on map distance between contours is called the [underlined] horizontal equivalent. [/underlined]

Make sure whether spot heights are in metres [deleted] offe [/deleted] or feet (if metres x 3.3 to get feet).

[underlined] Methods of Reporting Position. [indecipherable word] Ref. System. [/underlined]

Each deg. Lat. between 70° N & 70° S is represented by a pair of letters, also each degree of long.

[graph]

Point M reported as [deleted letters] RSGH3540 [underlined] always [/underlined] measure from bottom left hand corner.

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The Navy reports the bearing of a position and its distance for the nearest // meridian intersections.

E.g point N reported as 135VWAB 14 where 135 is the [symbol] & 14 ref distance.

The RAF method involves 4 separate cases.
[circled a] Latitude N long E (straightforward metres) (as RSGH 3540)

[circled b] Lat. N Long. W. Subtract westerly minutes from 60 & use the first of letters for the next higher degree of west longitude.
-eg. Point P reported as UVAB4005

[circled c] When lat is [indecipherable word] long E similar procedure is adopted to that for West long.
E.g. point O is XYGH1005.

[circled d] Lat S, long W.
E.g point N is XYAB3515

[underlined] Method used for logs [/underlined] (RAF)

The bearing of a position [underlined] from [/underlined] some [indecipherable word] land or sea mark, the name of the mark & distance of position from mark. E.g position of an aircraft & bearing 185° T from ST Cath. Pt. & 20 miles distance reported as 185 St Cath 20 (always in T)

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[underlined] Recall Signals [/underlined]

[diagram]
Local Recall

[diagram]
General Recall (nearest aerodrome)

[diagram]
General Recall (own aerodrome)

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[diagram] Right hand Circuit

[diagram]All clear

[diagram] Land with care

[diagram] landing prohibited

[diagram] To signal on ground that T is out

[diagram] GAS but can land, turn to windward side & wait

[diagram] smoke candle (change of ‘T’ circuit on air raid)

[diagram] (Air raid warning)

[diagram] Parachute Dropping

[diagram] yellow pyramid (long beam)

[diagram] (white) Dive bombing