ppl_03_e2

When lost in poor visibility, fly at the

Safety Altitude: 1 000 feet above the appropriate MEF.

Maintain

VMC and visual contact with the ground.

The normal

method of map

reading is map to ground. But, when putting into action the lost procedure, read from ground to map.

For example, if you suspected that there had been a 10° discrepancy in the synchronisation of the Direction Indicator so that your planned heading of 352º had actually been 342º, then you might assume that your track made good was 10° to the left of the required track.

Having estimated the distance flown along your probable track made good, mark this point as the dead reckoning position; then draw a circle around this point, with a radius of 10% of the estimated distance, as shown in Figure 14.3.

In Figure 14.3, you see the planned track from Ludlow to Hawarden that you studied in the chapter on “Practical Navigation”. You can also see the check feature South

West of Condover, which was the first checkpoint to be missed, and also the second checkpoint at Montford Bridge which we are now assuming does not appear on time, either.

The pilot, uncertain of his position, has drawn his probable track made good from the last identified fix, which was the turning point at Ludlow. At a groundspeed of 113 knots, the pilot estimates that he has flown 23 miles along that track. This gives him his mental dead reckoning position. From this position, the pilot draws a “circle of uncertainty” of radius 3 nautical miles, about 10% of distance flown.

Attempting to Establish Position Within the Circle of Uncertainty.

When map reading during visual navigation flights, the correct method is to read from chart to ground to confirm that the feature you are expecting to see is in the position it ought to be. But when you are lost, the process is reversed. Look within the circle of uncertainty for features that stand out on the ground, and then try to identify one or more of those features, on your chart. In other words, read from ground to chart.

Under no

circumstances must you run

out of fuel. If fuel is short, plan to land in a suitable field before fuel is exhausted.

AFTER HAVING RE-ESTABLISHED POSITION.

Having re-established his position from a positive fix, the pilot would set heading accurately from overhead Rednal, recording the new heading in his flight log, and establish radiotelephony contact with Hawarden, without delay.

In our imagined scenario, then, the pilot has re-established his position without too much delay and set a new heading for his destination. There would be no danger of running short of fuel in this scenario but always bear that possibility in mind.

Fuel Considerations.

Under no circumstances must you run out of fuel. Learn well the principles and techniques of the field landing when power is available (See OAAmedia’s CD-ROM, ‘Practical Flying Training’), and ensure that you have a safe margin of fuel and daylight. If you do have to land in a field, secure the aircraft against possible damage from livestock or wind, and telephone your home airfield as soon as possible.

Do not allow

a situation where you

are unsure of position, or lost, to develop into an emergency situation. Seek help from

an ATSU, in good time.

USE OF RADIO AIDS WHEN LOST OR UNSURE OF POSITION.

If you become lost on a visual navigation flight that you have planned and are flying using mental dead reckoning navigation techniques, you will probably judge it logical and practical to attempt to re-establish your position, at least initially, using a mental dead reckoning procedure along the lines of the lost procedure discussed in this chapter.

You may, however, elect to use radio-navigation position fixes and headings.

During the navigation part of the flying skills test, sometime after the first leg of the navigation test route, or during the practice diversion leg, you may be required to fix your position using radio aids and to intercept and briefly track a beacon radial using a radio aid nominated by the examiner; therefore, you will learn how to do this during your flying training.

Part Two of this book teaches you the basic theory of position-fixing and tracking, using VHF Direction Finding, Automatic Direction Finding, VHF OmniDirectional Range, Distance Measuring Equipment and radar services.

Whatever method you use to re-establish your position and to determine a new heading to your destination aerodrome, or to some other, nearby aerodrome, if you do not succeed in finding out where you are after a reasonable time, you should seek navigation assistance from an Air Traffic Service Unit (ATSU). Do this sooner rather than later; you must not allow your situation to develop into an emergency, where you are flying on into the unknown, running short of fuel and/or daylight, or about to stray, unannounced and unauthorised, into controlled airspace. You may also elect, in the United Kingdom, to seek a position fix and a heading to steer from one of the country’s two Distress and Diversion Cells on the international emergency frequency of 121.5 MHz.

THE USE OF PILOT-INTERPRETED RADIO-NAVIGATION AIDS TO OBTAIN A POSITION FIX.

Pilot-interpreted radio-navigation aids are fitted to many general aviation aircraft.

Those most commonly found in light aircraft are Automatic Direction Finding (ADF) (formerly referred to as the radio compass), VHF Omni Directional Radio Range (VOR), and Distance Measuring Equipment (DME). You will learn the principle of operation of these radio-navigation aids, and their use in position fixing and, in the case of ADF and VOR, obtaining headings to steer to arrive at the beacon, in the chapters which follow.

A pilot who had become lost on a visual navigation flight from Ludlow to Hawarden in the circumstances that we have just been considering, and whose aircraft was fitted with the necessary pilot-interpreted radio-navigation aids, would have a number of immediate options for determining his position or obtaining a heading to steer. These options are presented below. The order of presentation does not constitute a recommendation to use one method in preference to another; seek your flying instructor’s advice on that matter.

Refer to your 1:500 000 aeronautical chart of Southern England and Wales while reading through the next few paragraphs.

Option 1.

Hawarden, the destination aerodrome, is equipped with a Non Directional Beacon (NDB) and with a DME beacon. As you will learn in Chapter 16, an NDB is the ground element of an ADF system; so if the pilot has ADF fitted to his aircraft, he can get an immediate indication of the magnetic heading to steer to reach his destination. If he has DME, too, the pilot will also have range information to give him a constant read-out of his distance to run to Hawarden. The pilot should, however, continue to attempt to fix his position visually. This should be achieved as soon as possible; he is on a visual navigation flight in accordance with the Visual Flight Rules (VFR), so he should confirm visually his track over the ground as well as make early visual contact with Hawarden.

When uncertain of position

or lost under Visual Flight Rules, and tracking to an aerodrome using radionavigation aids, you should nevertheless fix your positon visually as soon as possible.

When using

a pilotinterpreted

radio-navigation aid, ensure that the beacon is the correct one by confirming the Morse identification code.

As with all radio navigation aids, the pilot must confirm that he is tuned into the correct beacon by listening to the beacon’s Morse Identification Code (or ‘ident’). The

Hawarden NDB operates on the frequency of 340 KHz (in April 2007) and its DME beacon has the frequency 110.35 MHz (in April 2007). These Hawarden beacons are identified by the letters HAW in Morse Code. (Morse Code is no longer tested in pilot examinations, but a Morse Code tutor is included on OAAmedia’s CD-ROM, ‘The IMC Rating and Instrument Flying’). The Morse Code is printed at the lower left corner of the ‘half-mil’ chart. It is a good idea to put the morse code for any beacons on the VFR Flight Log, although our example log doesn’t.

You will learn about the principles of operation and use of ADF in Chapter 16.

Option 2.

By tuning his VOR/DME equipment to the Shawbury VOR beacon and its co-located DME beacon, the pilot could determine his bearing and range from Shawbury

Aerodrome and, thereby, obtain an immediate position fix. If the pilot wished, he could use his VOR equipment to track to Shawbury and land there, after obtaining a clearance from the RAF controller of the Shawbury/Ternhill Combined Military

Aerodrome Traffic Zone (CMATZ). VOR is covered in Chapter 17.

Figure 14.6 Shawbury is equipped with VOR/DME on 116.8 MHz (2010).

Again, the pilot must confirm that he is tuned to the Shawbury VOR and DME beacons by listening to the Morse Identification Code. The Shawbury VOR and

DME beacons, both accessed through the same frequency of 116.8 MHz (in 2010), are identified by the letters SWB in Morse Code.

A visual confirmation of position must be made as soon as possible.

Option 3.

Though it would be a more cumbersome operation for a pilot-navigator operating alone, the pilot could obtain a DME range from Shawbury and a further DME range from his destination, Hawarden; drawing the two range arcs on his chart would give him a position fix. Beware the possibility of ambiguity, as two arcs can intersect twice, particularly if the aircraft is approximately between the beacons.

Figure 14.7 Welshpool has an NDB on 323 KHz, and DME on 115.95 MHz (2007).

Option 5.

As both Welshpool and Hawarden have NDBs, the pilot could use his ADF equipment to take bearings from both ground stations, enabling him to fix his position. Such an operation would, however, not be easy to carry out by a single pilot-navigator with one ADF set on board his aircraft.

Considerations for Using Pilot-Interpreted Radio Navigation

Equipment.

Do not make being lost or unsure of your position any more difficult than it need be.

Use the most logical navigation aid at your disposal and consider which is the easiest to interpret in re-establishing your position. Being already under some pressure to find out where you are, it may not be a good idea to have to think of drawing DME arcs or ADF bearing lines on your chart, in a cramped cockpit. Of course, you can, especially with practice, make good estimates of bearing and distance, by eye alone, but it is far easier to do this when you have only one direction and one distance to deal with.

Consequently, in the imaginary situation that we have been considering above, the most straightforward radio-navigation solution to adopt would be to follow an ADF heading to Hawarden, while reading off the range from your DME equipment. This solution to your predicament requires no drawing of lines on the chart, and should leave you with adequate spare mental capacity to fix your position visually, as soon

as possible.

When lost, you will probably not find it

practicable to have to draw position lines on your chart. Estimate bearing and distance.

If you cannot

re-establish your position

in a reasonable time, seek help from an ATSU or D&D Cell. Do not allow the situation to deteriorate into an emergency.

Figure 14.8 An emergency VDF service is provided in the United Kingdom by two Distress & Diversion Cells.

The emergency VDF service on 121.5 MHz is described in detail in Chapter 15.

AVIATE, NAVIGATE, COMMUNICATE.

Realising that one is lost is an unpleasant feeling, and may be a frightening one.

Above all, remain calm and bear in mind, at all times, the pilot’s order of flying priority: aviate, navigate, communicate. So, as top priority, fly the aircraft, then concentrate systematically on finding out where you are, and the direction in which you need to head.

If you have to report a deteriorating situation to an ATSU, make the decision to do so in good time; but under no circumstance must you relegate the need to fly the aircraft from its place at the top of your priorities.

If the situation dictates, do not delay contacting a D&D Cell on 121.5 MHz to obtain an emergency VDF service.