NAV GEN Flashcards
What is a great circle?
The shortest distance between 2 points on the earths surface.
How is the track changing on Great circle track
Constantly changing
What is a Rhumb line track?
A curved line on the earths surface that cuts all meridians at the same angle
Where is Rhumb line in comparison to a Great Circle track?
Always towars the nearer pole
When are Rhumb lines and Great circle tracks the same?
On the equator and along a meridian
What is the percentage difference between Rhumb lines and Great circle tracks for:
- 1200 nm
- 1800 nm
- 3600 nm
- 1,5%
- 3,5%
- 14,5 %
Below what distance are flight flown as Rhumb line tracks?
Below 1000 nm
How does GC tracks increase/decrease with easterly/westerly tracks?
North: Easterly-increase, westerly-decrease
South: Easterly-decrease, westerly-increase
How long is 1 nm in:
- meters
- Feet
- minutes
- 1852m
- 6080ft
- 1 min
How long is 1 degree in:
- minutes
- nm
- 60 minutes
2. 60nm
What is the distance between two meridians at:
- The equator
- The poles
- 60 nm
2. 0 nm
What is the formula for departure?
D long x cos Lat
Mnemonic for basic VFR navlog setup?
CDMVT
Compass deviation magnetic variation true
Mnemonic for variation/deviations effect on Magnetic/compass hdg?
Mag/Var east - Mag/Var least
Mag/Var west - Mag/Var best
How are relative bearing measured?
From the nose of the aircraft
How are magnetic bearing obtained if you dont have an RMI?
MH+RB=MB
What is an isogonal?
Same magnetic variation
Whats an Agonic line?
Isogonal where variation is zero
Describe the 1 in 60 rule. Draw an example
1 degree angle at 60 nm out gives a track error of 1 nm
Formula for track error?
Dist off x 60 divided by Dist to go
Formula for total alteration?
Dist off x 60 divided by Dist to go
+
Dist off x 60 divided by Dist gone
How are Rhumb lines/ Great circle lines depicted on Mercator/Lambert charts in N/S?
Mercator: RL are straight lines, GC are curved
Lambert: GC are straight, RL are curved convex to the EQ
How is TAS calculated from RAS/CAS with altitude?
Add 2% per 1000 ft
Where is convergency least/max?
Least at equator
Max at the poles
Formula for convergency?
D Long x sin Lat
Properties of a Mercator chart?
- Meridians are straight lines
- Latitudes are straight lines parallell to the EQ
- Dist between latitudes increasees as latitude increases
- Convergency is zero
- Scale expands away from the equator
Up to what latitudes are Mercator useful?
Up to 8 deg N/S
Does radio waves follow RL or GC tracks?
GC tracks
Are GC tracks (radio waves) straight or curved lines on a Mercator
They are curved
How are bearings from NDB:s converted and plotted on a Mercator?
- Convert Mag bearing to the beacon to true bearing using aircarft variation
- Apply conversion angle
- Take reciprocal to get RL from the beacon
How are bearing from VOR converted and plotted on a Mercator?
- Take reciprocal of RMI to get magnetic radial
- Apply conversion angle
- Convert to true bearing using station variation
Between what latitudes are Lambert chart useful?
8 deg to 75 deg N/S
How are RL and GC tracks depicted on a Lambert chart?
RL are curves concave to the equator
GC are straight lines
Properties of a Lambert chart?
Conical projection
2 std parallels
Scale expands away from the 2 std parallels
Scale is correct at the SP:s
How do we plot on a Lambert? NDB/VOR
RMI=65 deg
Var= 15E
Convergence=18 deg
80 deg True + 18 convergence= 98 deg true
Plot 98 deg T + 180 deg = 278 deg True
From what latitudes are Polar charts used?
75 deg - 90 deg N/S
Properties of Polar charts?
GC=curve concave to pole, near pole its a straight line
RL=curve concave to pole
Convergence is constant
Scale expands away from the pole
How many degrees are earths tilt angle?
23,5 deg
How many degrees does the earth spin in 24h?
360 deg
1 hour change in LMT, how much is that in degrees?
15 deg
1 degree of change in longitude, how much is that in minutes?
4 min
How does UTC change with longitude change East/West?
Long west - UTC best
Long east - UTC least
When is civil twilight?
Sun is 6 deg below the horizon
When and what is “Astronomical twilight”?
Sun is 18 deg below the horizon
It’s the moment of darkness
3 deg glideslope and 5nm from the threshold. What’s your height?
1500 ft
Height=Angle x 100 x range
Describe acceleration errors on a compass
North: ANDS
South: DNAS
Max on East/West headings
Describe turing errors on a compass
North: UNOS
South: ONUS
Max on North/South headings
Temp error correction formula?
Elevation 6200 ft
Altitude 11’800 ft
ISA dev = +5
TEC = 4 x (5600/1000) x +5
5’600 comes from 11’800-5’600
What is RNP and PBN?
Required navigation performance (RNP) is a type of performance-based navigation (PBN) that allows an aircraft to fly a specific path between two 3D-defined points in space
What’s the difference between RNAV and RNP?
Area navigation (RNAV) and RNP systems are fundamentally similar. The key difference between them is the requirement for on-board performance monitoring and alerting. A navigation specification that includes a requirement for on-board navigation performance monitoring and alerting is referred to as an RNP specification. One not having such a requirement is referred to as an RNAV specification. Therefore, if ATC Radar Monitoring is not provided, safe navigation in respect to terrain shall be self-monitored by the pilot and RNP shall be used instead of RNAV.
