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# PILOT NAVIGATION - PowerPoint PPT Presentation

PILOT NAVIGATION. Senior/Master Air Cadet. Learning Outcomes. Know the basic features of air navigation and navigational aids. Understand the techniques of flight planning. Understand the affects of weather on aviation. Flight Planning. Introduction.

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Presentation Transcript

Understand the techniques of flight planning

Understand the affects of weather on aviation

In Air Navigation, we discussed the Triangle of Velocities

We shall now revise the components of the Triangle and learn how this helps us to plan a flight.

Finally, we will learn how to co-ordinate our sortie with other agencies

Comprises 3 vectors drawn to scale

(a vector being a component of the Triangle, having both direction & speed)

One side shows movement of the aircraft in still air (HDG & TAS)

Another shows wind speed & direction(W/V)

The third shows actual movement of the aircraft over the surface of the earth (TK & G/S), resulting from the other 2 vectors

Thus there are 6 components

Wind Speed

Wind Direction

True Airspeed

Groundspeed

Track

As long as we have 4 of the components it can be solved by a number of methods:

Scale drawing on graph paper or map/chart

Mental arithmetic

Micro computers

Both in private aviation & military training, flight planning is carried out using a

Pilot Nav Log Card

On this card the flight is divided into a number of legs

Before flight, the Triangle Of Velocities is solved for each leg

First, the pilot needs to know the Tracks and Distances of the various legs

So he draws them on a route chart

We will now plan a VFR Tutor flight from Leeming to Marham via Cottesmore at 3000ft AMSL

Cottesmore

Marham

MAR

COT

For the purposes of our exercise, we have ignored any airspace issues or any airspace changes since this version of the chart was produced

Producing a headwind (G/S < TAS) and some port drift

180/30

The forecast wind is 220/25 for Leg 2

Producing a crosswind with port drift, plus a tailwind

220/25

The Pilot must enter some Log Card details before solving the Triangle of Velocities:

Track

Measured With A Protractor

Distance

Measured from map/chart against the Latitude scale or using a Nav ruler of same scale

MAR

161

096

98

44

Altitude or Height for each leg

Decided by operational, weather, safety & other needs

Forecast W/V

Forecast Air Temperature (Temp)

Indicated Air Speed (IAS)

Normally The Recommending Cruising Speed

True Airspeed (TAS)

Calculated from the IAS/RAS & Air Temperature using a Dalton Computer

Variation (Varn)

Found on the map/chart

To obtain TAS using the Dalton Computer

Set forecast temp +10C against 3000ft

From a 120kt IAS/RAS on the inner scale

We can obtain 125kt TAS on the outer

MAR

3000

3000

120

120

125

125

161

096

98

44

180/30

220/25

+10

+10

2W

2W

First we will use graph paper

Later we will use the

Dalton Computer

The theory is the same but, as you will see, the Dalton Computer is quicker

Once Track, Distance & TAS are known for each leg, the Triangle of Velocities can be used to calculate:

The Heading to counter the wind & fly the desired Track

The Groundspeed (G/S)

We already have 4 of the 6 elements of the triangle (1st leg)

NORTH (TRUE)

Flight Planning – Triangle of Velocities

We first draw the W/V from the direction 180º & give it a length of 3 units

(to represent 30 Kt)

Next, at the downwind end of the W/V draw the Track & G/S line on the reciprocal of 161ºT, for an unknown length

This length denoting G/S is one element we will discover

All we currently know is that G/S will be less than our TAS of 125 Kt

Next, from the upwind end of the W/V line, draw an arc representing TAS to a length of 12.5 graph units (125 knots), until it crosses the Track & G/S line

Then, with a protractor, measure the direction of the resultant Heading line & the length of the G/S line

Track 161T & G/S (to be measured)

W/V

3 units

Flight Planning – Triangle of Velocities

Drift

We calculate that the length of the Track & G/S line is 9.6 units, so the G/S Will Be 96 Kt

Using a protractor, the Heading is 166ºT

We can now apply the Varn of 2ºW to 166º(T) to give a Heading of 168º(M)

After entering this information on the Log Card, we can then calculate the Leg 1 time by using a G/S of 96knots & distance of 98nm

To calculate leg time – for Leg 1 put the black triangle under the 96 Kt G/S on outer scale

Then against the 98 nm distance on the outer scale

Extract a leg time of 61.3 mins on the inner scale

Repeat the exercise for Leg 2, to Marham

MAR

168M

108M

3000

3000

Notice that the info we will need readily at each turning point, is at the top.

Info that can be referred to in slower time, is further down the card

120

120

61.3

19.5

125

125

161

096

98

44

180/30

220/25

+10

+10

96

136

2W

2W

For Leg 1, put on the W/V 180/30

First, turn the dial until 180 or S is at the top

Then, put a mark 30kts below the centre circle

Next, turn the dial until Track 161 is at the top

Then, ensuring that the centre circle is over the TAS 125kts

Observe that there will be 5 degrees port drift

In order to fly the desired Track of 161, we will have to offset for the drift

We offset for the drift by turning the dial the opposite way - in this case 5 degrees right of Track 161

This gives us a Heading of 166(T), still with 5 degrees port drift

It also gives us 96Kts G/S

Repeat the process for Leg 2 (remembering to change the wind)

You can see that by using the Dalton Computer, we can solve the Triangle of Velocities more rapidly and conveniently than by scale drawing

If we wished to arrive overhead Marham at a particular time, say 1000hrs, we can now calculate a departure time from overhead Leeming, in addition to a time overhead Cottesmore

Flight time is 61.3 mins to Cottesmore and 80.8 mins total to Marham

Therefore we can annotate our Log Card with the desired times (ETA COT 0940.5, ETA MAR 1000.0 & ETD LEE 0839.2

MAR

168M

108M

3000

3000

120

120

61.3

19.5

0839.2

0940.5

1000

125

125

161

096

98

44

180/30

220/25

+10

+10

96

136

2W

2W

One of the main purposes of calculating flight times is to ensure sufficient fuel is available

Running a car out of fuel will be inconvenient

In an aircraft…… it could be fatal

At the planned altitude and speed, the Tutor consumes fuel at:

48 Kg an hour

48/60 X 61.3 mins = 49.0 Kg

So 49 Kg is needed for Leg 1

Similarly, for Leg 2, 16Kg is required

Total fuel required is therefore 49+16 = 65Kg, although in reality, additional fuel would be needed for Take-off, Recovery & Diversion

If we require 55 Kg minimum overhead Marham for recovery and diversion purposes, we can annotate our Log Card for fuel

MAR

168M

108M

3000

3000

120

120

61.3

19.5

0839.2

0940.5

1000

120

71

55

125

125

161

096

98

44

180/30

220/25

+10

+10

96

136

2W

2W

The most important is the Safety Altitude

This is the altitude an aircraft must climb to or not fly below in

Instrument Meteorological Conditions (IMC)

This ensures the aircraft does not hit the ground or obstacles such as TV masts

Safety Altitude is calculated by adding 1000ft to the highest elevation on or close to the planned route (RAF use 30nm) & rounding it up to the next 100ft

In mountainous regions, a greater safety margin is added

An aircraft can not descend below the Safety Altitude unless the crew has:

Good visual contact with the ground

or the services of ATC

(Apart from specially equipped aircraft such as Tornado GR4 which can, when appropriate, use TFR)

Using the guidelines, we calculate Safety Altitude as 3600ft for Leg 1 & 2600ft for Leg 2

As we plan to fly the route at 3000ft AMSL, if we encountered poor weather during Leg 1, we would have to climb to 3600ft until conditions improved

We can now enter Safety Altitude figures on our Log Card

MAR

168M

108M

3000

3000

120

120

61.3

19.5

0839.2

0940.5

1000

120

71

55

3600

2600

125

125

161

096

98

44

180/30

220/25

+10

+10

96

136

2W

2W

This notification is usually in the form of an ATC Flight Plan

Sortie Co-ordination

Ideally prior to flight, aircraft crews must notify ATC of their sortie details, so that action can be initiated if the aircraft becomes overdue at its planned destination

Additionally, the crews of aircraft planned to enter busy airspace have to submit an ATC Flight Plan.

This is to enable their flight to be coordinated with other aircraft using that airspace

ATC has a standard format for this, including:

Aircrafttype

Aircraft callsign

Route

Time & place of departure

ETA and destination

Speed & altitude

Safety info

In the UK, we submit an ATC Flight Plan using a CA48 or RAF Form 2919

The principles of flight planning are the same for an intercontinental flight in an airliner, or a cross-country flight in a light aircraft

Prior to a flight we must:

• Measure Tracks, Distances and Safety Altitude from the chart or current databases

• Calculate the effects of the weather (especially wind)

• Have sufficient fuel

• Inform ATC of our planned route

This will minimise risk and ensure that if anything goes wrong, assistance should be readily available

In the pioneering days of aviation, aircraft would not usually fly unless the crew could see the ground, as map reading was the only means of navigation

Later, aircraft were fitted with sextants & radio direction-finding equipment. However, significant improvements to navigation capability occurred during & after WW2…

It was not until the 1970’s that a navigational aid with world-wide coverage was available (apart from Astro Navigation)

Omega

More recently Satellite Navigation (SatNav) & the Global Positioning System (GPS) have replaced previous world-wide systems

Any process of finding an aircraft’s position is known as

Fixing

During a sortie, aircrew need to be able to fix their position, not only to monitor progress against fuel reserves, but also to stay away from areas best avoided

VisualFixing

There are many factors affecting map reading

When we are able to determine our position with reference to ground features observed from the aircraft, this visual fix is known as a Pinpoint

The accuracy of our Pinpoint depends on the uniqueness of the features, distance from these features, accuracy of the map & skill of the observer

Mapreading is a reliable method of navigation & it is used frequently by aircrew

The use of radio aids for navigation enabled aircraft position to be fixed without reference to ground features

If you rotate a radio aerial through 360º in the horizontal plane, you will find 2 directions where radio reception is better than others

Radio Direction Finding (RDF) uses this principle. By turning the aerial until the best reception is received, aircraft equipment will display the bearing to a transmitting beacon.

As long as the position of the beacon is known, a Position Line can be drawn from this, towards the estimated aircraft position, the aircraft being somewhere along this line

If another position line can be obtained, preferably at 90º to the first, fixingis possible

If 3 position lines can be plotted, from different sources, preferably at 60º to one another, then a ‘3 position line fix’ can be obtained

If the 3 lines do not intersect, an indication of reliability may be possible, unlike with just 2 lines

Traditionally, using 3 position lines was a main method of fixing. However, the further the beacons, the greater the errors

Also, at long distance from beacons such as during trans-oceanic flights, fixing opportunities were often lacking

Furthermore, constructing fixes from position lines was very time consuming, requiring a crew member to act as Navigator

VOR/DME & TACAN beacons are the modern method of gathering position lines, or indeed an instant fix

Navigation information is usually displayed on the Horizontal Situation Indicator

This aircraft is on radial 191, 84.5nm from the beacon

Rather than plotting, modern equipment allows radial/range data to directly update aircraft systems

TACAN is a military system, & gives the magnetic bearing, or radial, from the beacon to the aircraft and the slant range

Slant range is the increased distance indicated due to the relative altitude of the aircraft above the beacon

Altitude

Slant Range

Ground Range

Yeovilton TACAN Channel 47

Transmits Morse code VLN

Bearing - 280º

Slant - 35 nm

Aircraft with DME can obtain range only, on frequency 111.0

Similarly, at Yeovil/Westland, a DME provides range only on TACAN Channel 27 or DME frequency 109.5

VOR/DME is a civilian system

VOR/DME gives the magnetic bearing, or radial, from the beacon to the aircraft, plus the slant range. However, the bearing information is less accurate than TACAN

Civil aircraft generally fly from beacon to beacon

Lambourne VOR/DME, frequency 115.6, Transmits Morse code LAM

Military aircraft with TACAN can obtain range only on Channel 103

Both VOR & TACAN bearings are generated by the ground station, but ranges for both require aircraft transmissions

In hostilities, TACAN and VOR/DME beacons may not be available

If radio beacons are lacking, such as during sorties across oceans, aircrew can also use thestars, or Astro Navigation

The principle behind Astro is that if you have a reasonable estimate of your position, you can calculate the elevation of heavenly bodies such as the sun, the moon, the planets & the stars

Then, using a sextant to accurately measure the elevation of the heavenly body above the horizon, you can compare your actual position to the estimated one

The difference between the 2 equates to a linear position error

2 or 3 position lines are still required for a fix, although an Astro line can be combined with lines from radio aids

With practice, Astro can be accurate, but it is being superseded byGPS

Astro is weather dependent; however, it cannot be jammed by an enemy!

Radar was invented in the 1930’s & rapidly developed

Early systems where crude & unreliable

Modern systems , such as used in Tornado, are highly effective

The radar is used to illuminate known ground features and rapidly update any error between estimated and actual position

Aircrew can then concentrate on other tasks, such as weapon-system management

The main problem is that the radar transmits electronic emissions which are usually unique for the type of radar

This can lead not only to aircraft detection, but also type identification

However, not only is aircraft radar independent of external aids, but also it works in all weather

With the rapid development of electronics in the 1950’s & 60’s, area navigation systems were also introduced :

GEE

DECCA

LORAN

OMEGA

These systems involved signals transmitted from ground stations and not from the aircraft using them

These systems work by measuring the time taken for synchronized signals to arrive from 2 different stations.

Each pair gives a position line

Introduced in the 1940s, the Gee system allowed aircrew to fix their position accurately

Plotting the intersection of 2 range position lines, provided an aircraft Latitude and Longitude

However, coverage was limited & using the system was time consuming

Later systems such as Decca & Loran worked on similar principles to Gee

However, as technology progressed, systems became more automated & had greater coverage

With the advent of SatNav & in particular GPS, fixes are available at the touch of a button, throughout the world, in 3 dimensions & with an accuracy of a few metres

GPS measures time difference between signals received from satellites of known position & an accurate master clock

The time difference received from each satellite is then converted to a range

GPS

Ranges from 3 satellites will produce a fix in the horizontal plane

Ranges from 4 or more satellites produces a 3-dimensional fix. This is required for weapon solutions in military aircraft

Active/Passive Systems satellites of known position & an accurate master clock

As stated, the main disadvantage of radar is that it could alert an enemy to the presence of the aircraft, thereby invoking the timely activation of enemy forces or electronic countermeasures such as jamming

Radar homing missiles have been developed against surface radars. In the future these could also be developed against radar-equipped aircraft

Active/Passive Systems satellites of known position & an accurate master clock

Developments in Electronic Warfare (EW), such as frequency-hopping radars which minimise the effect of jamming, can protect active navigation systems in a hostile environment

However, the problem of aircraft detection still exists

A solution is to use equipment that does not transmit, but merely receive

Passive Systems

Active/Passive Systems satellites of known position & an accurate master clock

Passive Systems include GPS-blended navigation solutions, with fixing taking place continuously, to keep the navigation and weapon systems constantly updated

Aircraft may also still retain active systems, not only for their role, but also for flexibility in poor weather & equipment redundancy

Fixing - Summary satellites of known position & an accurate master clock

Technological developments have enabled aircrew to fix their position in a variety of ways beyond Pinpoints

Position-line fixing using radio aids and Astro has been superseded by instant fixing using TACAN or VOR/DME

Long-range systems have gradually developed until accurate fixing is available instantly & world wide

Radar permits rapid, independent fixing, but use of such an active system may forewarn a potential enemy

Passive systems offer advantages but aircraft may retain active sensors for flexibility

### PILOT NAVIGATION satellites of known position & an accurate master clock

END OF LEARNING OUTCOME 2