Navigation and Flight Planning

Objective

To provide the student with the necessary knowledge about flight planning, preparing an operational flight plan, filing an ATS flight plan and making an appropriate go/no-go decision based on available weather forecasts.

Equipment

  • Whiteboard
  • Terminal chart
  • Operational flight plan
  • ATS flight plan
  • Plotter & Flight computer
  • Calculator
  • POH

Elements

Common Errors

  • Not taking current winds into account for an operational flight plan
  • Improper selection of suitable waypoints

Schedule

  • Introduction 3 min
  • Development 90 min
  • Conclusion 3 min

Completion Standards

The lesson is complete when the instructor has deemed either through oral or written quizzing that the student is proficient in the content of this lesson. The student should also be able to prepare an own operational flight plan without assistance from the instructor.

References

  • FAR/AIM

Introduction

Before each cross-country flight we are ever going to do in our future flying career we are likely to prepare an operational flight plan. At an airline, there are most likely computer based programs that will do our flight plans, but nonetheless it is important that we know how to prepare one.
Today we are going to learn VFR navigation.
Pilotage: Term for navigation by reference to the ground, visual landmarks and checkpoints.
Dead reckoning: Navigation solely based on computations of time, airspeed and heading. Could be used when flying over a large mass of water.

Terms in navigation

Latitudes and longitudes

  • Latitudes (or parallels) are circles parallel to the Equator, 0⁰ at the Equator 90⁰ at the poles. They are measured N or S of equator.
  • Longitudes (or meridians) run from one pole to the other and cross the equator with 90⁰. They are measured E or W of the prime meridian through Greenwich.
  • Latitudes and longitudes are defining our spot on earth.

Charts

  • Sectional charts, scale 1:500 000.
  • Terminal charts, scale 1:250 000.
  • Revised twice a year.
  • Show chart legend.

Terms

  • Track: Actual path over ground
  • Heading: In the direction the nose is pointing. Not the same as track because of wind.
  • Drift angle: Angle between track and heading.
  • Wind correction angle: Angle between heading and track.
  • True airspeed: Our speed through the air
  • Groundspeed: Our speed over ground. Not the same as true airspeed because of wind.

Variation & Deviation

  • Variation: The geographic north pole (or true north) does not coincide with the magnetic north pole. Because of this there is a difference between heading calculated on the map and the one the compass shows us.
  • Deviation: Thanks to local magnetic fields in our aircraft the compass north (where the needle is pointing) is slightly different from magnetic north too.

Obtaining a weather briefing

  • The first thing we will do when we have selected our departure and destination airport is to obtain a weather briefing.
  • The weather briefing might influence our choice of route and altitude. Perhaps the weather is so poor it is not even worth planning at all.
  • Weather briefing can be obtained by calling the FSS. You will obtain the weather in the following order:
    • Adverse weather conditions
    • VFR flight not recommended
    • Synopsis
    • Enroute forecast
    • Destination forecast
    • Winds aloft
    • NOTAM
  • You could also obtain a weather briefing using for example www.duats.com

Preparing an operational flight plan

  • For the following scenario we assume that we are going to fly from Gillespie (KSEE) to John Wayne (KSNA). For that we need certain equipment:
    • Current VFR terminal chart. Important to check they are current since airspaces, obstacles etc. could have changed over time. Revised twice a year.
    • Plotter to plot our tracks
    • Navigational computer to calculate wind correction angle and ground speed
    • Calculator facilitates our calculations.
  • The weather and NOTAMS we have printed from www.duats.com.

Selecting route

  • Use easy to see navigation points on the ground. In this case it is easy to just follow the coastline up north.
  • Select way points not too far apart, maybe 20-30 min, to give opportunity for follow up of time.
  • Pre-determined VFR points are “flagged” on the map. They normally provide some feature on the ground that is easy to navigate by.
  • Also consider airspaces, proximity to other airports (in case of diversion), terrain etc.

Selecting altitude

  • Select an appropriate VFR altitude. Semi-circular rule shall be considered above 3000 ft AGL and 500 ft should be added.
  • Choose an appropriate altitude considering airspaces and winds aloft.
  • In our case, since we are going west, we choose 4500 ft.

Top of Climb (TOC)

  • During the climb to our cruising altitude
  • Use the POH for fuel, time and distance to climb.
  • For this flight, climb from Gillespie to 4500 ft gives 7 min, 1,8 USG and 9 NAM using ISA figures.  Note that we have to add 1,4 USG for start-up and taxi.

Determining Top of Descent (TOD)

  • Use the fact that you are descending with 500 fpm and traveling at our cruise ground speed (give or take for different winds), gives a good approximation for C172RG.

Now we can fill in our OFP with the route, including TOC & TOD, and altitude.
Show an OFP on the board and fill it in with the students.

W/V, TAS, True Track to Compass Heading

  • Fill in the Wind & Velocity for the appropriate altitude.
  • Fill in the TAS derived from the POH. Using 22 in/2200 rpm at 4500 ft in ISA condition gives us 122 kts.
  • Describe how to determine true track and fill in the OFP.
  • Since our compass will point towards compass north, and we have to correct for wind, we have to make some “corrections” to follow our true track.
  • Describe relationship between TT, Var, MT, Wca, MH, Dev, CH.
  • Describe how to obtain variation using isogons (13E for our flight) and fill in magnetic track.
  • Show how to use the flight computer to obtain wind correction angle and ground speed. Fill in magnetic heading and ground speed.
  • Describe how to obtain deviation and fill in compass heading.

Distance, Time, Fuel and Gross Weight

  • NAM to TOC was 9 nm. Distance to TOC is obtain by using the formula: NGM/GS = NAM/TAS.
  • Distance to TOD is obtained by us knowing how long time it will take to descend, and our ground speed during descent.
  • Use the plotter to determine the distances between each consecutive waypoint.
    • INT = Distance between each waypoint
    • TOT = Total distance covered
  • Use the formula: “Distance = Speed * Time” to obtain the time between each consecutive waypoint.
    • INT = Time between each waypoint
    • TOT = Total time covered
  • I normally add 10 min for approach at destination.
  • Fuel consumption to TOC is already covered. If we go into the tables, using 4500 ft and 22 in/2200 rpm in ISA conditions, we will have a fuel flow of 8,3 USG per hour. Fuel consumption between each waypoint is obtained by multiplying fuel flow with time between each waypoint.
    • INT = Fuel consumption between each waypoint
    • REM = Total fuel remaining at each waypoint
  • Fuel could be expressed as either USG or lbs in the OFP.
  • Expressing fuel in lbs could have the advantage that it is easy to convert into time if we assume the 10 USG/h = 60 lbs/h = 1 lbs/min, in case of diversion.
  • We need at least 30 min of fuel at cruise consumption for VFR day, and 45 min for VFR night.
  • Subtract fuel consumption to take-off weight, and we will have our gross weight at each waypoint.

ETO, ATO, DIF, RETO

  • To keep follow-up on your progress during the flight is important, i.e. the headwinds are stronger than expected and you are operating on minimum fuel.
  • ETO = Estimated Time Over. After the first point where you can get an accurate time passage (i.e. Mount Soledad at time 48) you can calculate your ETO for all waypoints further down the route.
  • ATO = Actual Time Over. After you pass overhead a waypoint, you write down your ATO. If this one varies from previously calculated ETO you have a difference.
  • DIF = Difference.  The difference between ETO and ATO is written down in this column. -1 equals one minute ahead of planning, +1 equals one minute behind of planning.
  • RETO = Re-Estimated Time Over. Assume your ETO for waypoint “Power plant” is 58 and ETO for “VPSMP” is 03. Your ATO for “Power plant” became 56 so Dif. is -2. Now your RETO for “VPSMP” is 01.
  • ETO +/- Dif. = RETO

Lost procedure and diversion

Lost procedure

  • Should you find yourself lost during the navigation, don’t panic! Follow this procedure:
  • First admit that you are lost, happens to all once in a while.
  • Consider circling instead of just continuing in a straight line, won’t get you more off-track.
  • Look for major features of the terrain and large prominent objects such as mountains and lakes.
  • Use NAVAIDS and try to pinpoint your position. You can also use VDF by requesting “QDM”.
    • NDB = Points straight to the beacon.
    • VOR = Center the needle with a FROM indication gives the magnetic track you are on.
    • GPS = A map show you where you are in relation to airspaces and other airports etc.

Diversion

  • If you for some reason can’t make it to the destination airport you need to be able to quickly, safely and accurately determine heading, time and fuel consumption to an alternate airport.
  • Use the plotter to obtain a heading or use a nearby VOR and a straight “piece of something”.
  • Choose an appropriate altitude clear of terrain and airspaces (or request clearance). Under radar coverage you can also ask for vectors.
  • Once established towards your new destination, use pilotage and update your heading. Calculate time and fuel using dead reckoning. 1 lbs = min.

Filing an ATS flight plan

  • Reference: Page 682 in FAR/AIM
  • Show an ATS flight plan on the board and fill it in together with the students.
  • The ATS flight plan is filed with the FSS and remains in the system one hour after proposed departure time.
  • The prime purpose of ATS flight plan is SAR. Initiated 30 min after proposed ETA if not closed. Remember, the tower upon arrival does NOT close the flight plan.
  • Recommended to file multiple flight plans if your flight contain stopovers more than 1 hour.
    • Block 1: VFR
    • Block 2: Enter the aircraft’s registration
    • Block 3: Fill in aircraft type and special equipment (reference FAR/AIM page 685). G = GPS, DME, Mode C, A = DME, Mode C, U = Mode C
    • Block 4: Enter TAS
    • Block 5: Enter departure ICAO designator, or if unknown, airport name.
    • Block 6: Departure time in UTC
    • Block 7: Enter appropriate VFR altitude
    • Block 8: Define the route to be flown using NAVAID identification codes and airways.
    • Block 9: Enter arrival ICAO designator, or if unknown, airport name
    • Block 10: Enter your estimated time Enroute in hours and minutes
    • Block 11: Remarks to ATC, i.e. clarifications.
    • Block 12: Enter fuel onboard in hours and minutes
    • Block 13: Enter alternate airport if desired.
    • Block 14: Enter your name, address, telephone number and home base. This is for SAR.
    • Block 15: Enter number of persons onboard
    • Block 16: Enter the prominent colours of the aircraft.
    • Block 17: Enter the name of the FSS that should close the flight plan.

Conclusion

Plan your flight, fly your plan!

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