061 GNAV - ATPLQ Memory Items

Words

• Parallels of Latitude.

• Meridians of Longitude.

• Concave: away from.

• ATIS & TWR wind = magnetic, METAR wind = true.

• The Earth spins from West to East, Counter-clockwise seen from North.

• Isosceles: the sides connected through the 90-angle, have the same length.

• Northern/Southern vertex: just the hemisphere it is on.

Agonic Aclinic Isoclinic

• Agonic: line where the magnetic variation is 0° (compass needle points to TN).

  • Isogonals: lines of equal variation.

  • High Variation on High Latitudes.

• Aclinic: line where there is no dip (only horizontal field) = the Equator.

  • Isoclinic: line of equal horizontal field strength/dip.

Geographic/Geodetic/Geocentric

• Geographic/Geodetic: Perpendicular from the surface - 90° "inside" - does NOT cross the centre of the earth.

  • perpendicular..ellipsoid..equatorial plane.

• Geocentric: measured from the Earth's center - crosses Earth Centre. Only 90° angle at Equator and Poles.

• Difference between the 2: because of the shape of the Earth vs Perfect Globe.

Degrees

• Degree = ° (hour)

• Minute = ' (=1/60°)

• Second = ''.

TEA (TKE) & CA

• Correction to TEA → Paralleling the Original Track.

• TEA = (DoT * 60) / DaT.

  • Drift Left, Correct Right.

• Remaining Distance Along Track (RDAT)

  • CA = (DoT * 60) / RDAT.

• Total Correction = TEA + CA.

Drift

• Drift = difference True Heading and Actual Track (TMG).

  • WCA and Drift are opposite and equal to each other.

  • Actual Track = HDG +/- Drift

Crosswind Component, MDR

• Crosswind = Clock.

• XWC = wind speed * clock factor.

• Based on sin(WA):

  • 15° = 15 minutes = ¼ past.

    • 30° = 30 minutes = ½ past.

    • 60° = 60 min = 1 hour.

    • 20° = 20 min = 33%.

• For Tailwinds: take the Reciprocal of the ACFT heading!

Drift, MDR

Angle between True Heading and True Track

• First: XWC clock rule.

• Then: TT = (XWC * 60) / TAS.

Head/Tailwind Component, MDR

• (90° - WA) + Aid Multiplier = Percentage of WS as HWC/TWC.

• First: 90° - WA = X.

• Then: look up X in the Aid Table.

  • 10° → 60°, >60°.

  • 1, 1, 2, 2, 3, 3, 3.

  • Aid * 10.

  • Aid + X = % HWC/TWC

• Again: Tailwind, take the reciprocal.

HWC/TWC, geometric

• XWC: wind speed x Sin(Angle).

• HWC: wind speed x Cos(Angle).

  • HC, CS.

Time

• ST: the time on the clock at that location. UTC -/+ something.

• LT: based on the exact longitude at the exact loaction.

  • East has the sun Earlier! Long. East, UTC Least!

  • Sunrise, sunset and twilight occur at the same LMT for all places on the same latitude for a particular date.

• UTC: ST at Greenwich.

IDL

• Westerly: add a Day, subtract an hour.

• Easterly: subtract a Day, add an hour.

• When using UTC, the date-line is irrelevant.

Length of Day

• Latitude

• Inclination/Time of Year

• Altitude/Elevation (higher = earlier sunrise due to greater horizontal visibility)

• Civil Twilight:

  • From Sunset/6°-below until 6°-below/Sunrise.

Equinox/Solstice

• Equinox: directly above the Equator.

  • Fastest/largest change in Daylight.

  • Solar Declination = 0° (smallest).

• Solstice: daylight period change is Slow.

  • Summer: longest day. Overhead Cancer (23.5° N).

  • Winter: shortest day. Overhead Capricorn (23.5° S).

• Mean Time = Mean Sun.

Days

• Apparent Solar Day: Time between two real Sun transits over the same meridian.

• Mean Solar Day: Average length of apparent solar days over a year. Constant length, Basis for civil time.

• Sidereal Day: Measured relative to distant stars. Nearly constant in length.

Projections, general

• A conformal projection preserves angles, Distortion is uniform in all directions at any point.

  • Scale N-S = E-W over the same (small) distance.

• EASA Bonus: ICAO Conformal = a Lambert chart.

• GC always concave (away) to PO!

  • MERCATOR = equator.

  • LAMBERT = between standard parallels.

  • POLAR = Pole (but less curvature than RL).

• RL always concave to the Pole, except in Mercator

Projections, Convergency

• Conversion Angle: Angle difference between GC and RL.

  • = 0.5 * Convergency = Delta Lon. * sin(mean Lat.).

  • Smallest at the Equator.

Projections, Mercator

• Chart has no Convergency (all meridians are straight & equally spaced).

  • But, Earth Convergency still exists.

    • Delta(Lon.) * sin(mean Lat.)

• RL = Straight.

• GC only straight on Equator and Meridians (equal to RL) - else concave to Equator.

  • GC cannot be drawn on a Mercator!

    • While radio navs are GCs!

• Scale: usually relative to Equator, else ABBA - with cos(x)!

• Scale increases from the Equator.

Projections, Lambert

• Chart Convergency is now Delta(Lon.) * sin(POO)

  • Within the whole chart, the chart convergency doesn't change!

• EC = CC at POO, above EC>CC, below EC<CC.

• Scale = Scale at the Std. Parallels.

  • Between: Decrease, Away: Expands.

• RL is Concave (away from) to the Pole.

• GC = Concave to POO (small), at POO straight.

Projections, Polar Stereographic

• Convergence = Change in Longitude.

• Convergence Angle = 0.5 x Convergence.

  • = diff. RL and CL.

  • RL is a Circle/Concave.

  • GC also, but less. Assumed straight >70°.

  • Isosceles Triangle when same latitude.

Convergence Angle vs Convergency

• Difference between Initial or Final GC and RL is the CA.

• Difference between Initial and Final GC track is the Total Convergency.

• Northern Hemisphere:

  • Flying East, GC Track Increases.

  • Flying West, GC Track Decreases.

  • D - I / I - D

• VOR Radials are GCs! Relative to MAGNETIC NORTH at that location!

• At the CG Vertex, the direction is always 90° or 270°.

Scales

• Big Denominator, Small Scale.

• Small Denominator, Large Scale.

  • Large Scale = a big scale model airplane.

Good to Know:

• 1 in. = 2.54 cm.

• 1 NM = 1852 m = 185200 cm.

Distances

• Along a Meridian (of Longitude), 1° = 60 NM.

  • 1° at the Equator = 59.7 NM, 1° at the Poles = 60.3 NM.

  • Thus, 1° = 60 at 45° latitude.

VFR, general

• VFR: obstacles in feet above MSL.

  • AGL only when >1000 ft tall, and in brackets behind the AMSL.

• Track Deviations: line in same direction/parallel.

• Time/Progresss: line in perpendicular direction.

• Hold the relevant Map segment, Track UP, for easy navigation

  • Hold it North UP, for reading the labels, frequencies, information.

• Relief: CS on a DS - contour (brown!), shading, different colour, spot height.

VFR, good checkpoints

• Best VFR checkpoints:

  • Large. Prominent.

    • Rail, Highway, Intersections, Rivers. Towers.

  • Contrasting.

  • Close to the track.

  • Consider Altitude: features may hide behind landscape, or pass by too quickly.

• Worst: Telephone lines and farmland.

Low Level VFR: downsides

• Obscured horizon due to high ground, making attitude flying harder

• Frequent airspeed adjustments over uneven terrain

• Restricted visibility ahead and around due to terrain folds

• Low-angle view makes flat features harder to spot

• Checkpoints may be hidden or only visible briefly after passing overhead

Low Level VFR, checkpoints

• Tall/vertical objects are easier to see

• Groundspeed feels faster at low level

• Navigation features are easier to identify from higher altitude than when blocked by terrain.

VFR, Position Uncertain

• Always maintain VMC, track fuel status, and be ready for a precautionary landing if needed.

• Low Level, Snowy = Climb to a higher level, then Lost Procedure.

1. Note the time.

2. Contact ATC for assistance.

3. Use available radio nav-aids.

4. If needed, call PAN on 121.5 MHz.

5. Fly straight and level on planned heading.

6. Estimate distance from last known position.

7. Match ground features with the map using prominent line features (e.g., coastlines, railways, highways).

8. After regaining position, update regularly and look for unique terrain or man-made features.

Dead Reckoning

Estimated position based on:

• Time, heading, airspeed, and wind data

• Used when no nav aids or visual references are available.

• Basically navigating based on your Flight Plan.

Accuracy:

• Time since last known.

• Difference between actual/forecasted wind, accuracy of wind forecast, heading, TAS (DISPUTED).

• Pilot skill.

Other Formulas

• Rate of Climb = Climb Gradient(%) x GS x (6080 / 6000).

  • GNAV = GS, PERF.: = TAS or GS.

• Degrees = Gradient * 60.

• Gradient (%) = Degrees / 60, (*100).

True Altitude to Pressure:

• True to Altitude (altimeter): PA = 4 * ISA * Height/1000.