IED FIELD
DEFUSAL MANUAL

ISSUED TO EXPLOSIVE ORDNANCE DISPOSAL
SUPPORT PERSONNEL

Version 1
Verification Code: 806
Issued with the device. Retain for the duration of the task.
IED Field Defusal Manual v. 1Defusing Devices

Defusing Devices

You are not holding the wire cutters. Someone else is. Speak clearly, ask for colours before you ask for opinions, and never say "just" before an instruction.

A device detonates when its countdown timer reaches 00:00, or when three strikes have been recorded against it. A device is defused only when every module on the panel has been disarmed. There is no partial credit.

Getting the Panel Open

The casing opens in three stages, in this order. Each stage needs the correct tool in hand:

  1. Remove the phone — cutting tool. Until this is done the device carries a live manual detonator that anyone standing nearby can trigger. Clear the area first.
  2. Open the case — opening tool (screwdriver). Exposes the internals.
  3. Open the defusal panel — cutting tool. The six module slots become reachable.
HANDLING WARNING. Knocking into the phone housing can set the device off outright. The odds are poor rather than terrible, but they are rolled every single time contact is made. Approach once, deliberately, and stop moving.

The Panel

Six slots, filled left to right, top to bottom, in a fixed order:

Slot 1Slot 2Slot 3 Slot 4Slot 5Slot 6
WiresWiresThe Button Simon SaysPasswordsKeypad

A slot flashes green when its module is disarmed and red when it records a strike. A red slot that stays red is dead — that module has locked and cannot be retried. A red flash that fades means the operator may try again.

Strikes

Three strikes detonate the device. Strikes also change the answer on the Simon Says module (see page 6), so call out every strike the moment it happens and re-check any module whose instructions mention them.

Walking Away

The EXIT control closes the panel and steps the device back to the opened-case stage. It does not stop the countdown, and it does not make the device safe. Anything already solved stays solved.

Duds

A small proportion of devices are inert and will fizzle rather than detonate. You will not know which until it is far too late to matter. Treat every device as live.

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IED Field Defusal Manual v. 1Section 1: Modules

Section 1: Modules

Every module on the panel must be disarmed before the countdown expires. Modules may be worked in any order, and one module's answer never depends on another's.

Two pieces of information sit outside the modules and are needed by several of them: the serial number and the strike count. Ask for the serial before you ask for anything else.

WiresPage 4
The ButtonPage 5
Simon SaysPage 6
PasswordsPage 7
KeypadPage 8
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IED Field Defusal Manual v. 1Wires

On the Subject of Wires

Six inches of copper and a colour scheme decided by somebody in a hurry. Count them twice before anyone touches anything.

3 wires:

No red wires — cut the second wire.

Otherwise, last wire is white — cut the last wire.

Otherwise, more than one blue wire — cut the last blue wire.

Otherwise — cut the last wire.

4 wires:

More than one red wire and the serial number ends in an odd digit — cut the last red wire.

Otherwise, last wire is yellow and there are no red wires — cut the first wire.

Otherwise, exactly one blue wire — cut the first wire.

Otherwise, more than one yellow wire — cut the last wire.

Otherwise — cut the second wire.

5 wires:

Last wire is black and the serial number ends in an odd digit — cut the fourth wire.

Otherwise, exactly one red wire and more than one yellow wire — cut the first wire.

Otherwise, no black wires — cut the second wire.

Otherwise — cut the first wire.

6 wires:

No yellow wires and the serial number ends in an odd digit — cut the third wire.

Otherwise, exactly one yellow wire and more than one white wire — cut the fourth wire.

Otherwise, no red wires — cut the last wire.

Otherwise — cut the fourth wire.

Reading the serial: see Appendix A. Only the last digit matters here — if the serial ends in a letter, keep reading backwards until you reach a number.

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IED Field Defusal Manual v. 1The Button

On the Subject of The Button

The word printed on a button is not a suggestion, an instruction, or a promise. It is one input out of four.

Work through the list below in order and carry out the first line that applies. Nothing further down the list matters once a line has matched.

  1. Blue button reading Abort — hold it, then see "Releasing a Held Button".
  2. Button reads Detonate and the serial's digits add up to an even number — press and release immediately.
  3. White button and the serial's last digit is odd — hold it, then see "Releasing a Held Button".
  4. Black button and the serial contains a 4 anywhere — press and release immediately.
  5. Yellow button, any text — hold it, then see "Releasing a Held Button".
  6. Red button reading Hold — press and release immediately.
  7. Anything else — hold it, then see "Releasing a Held Button".

Button colours in use: blue, white, yellow, red, black. Button text is always one of Abort, Detonate, Hold or Press.

Everything this module needs is on the panel readout. Work the serial out once, on paper, before you start reading rules: the digit total, the last digit, and whether a 4 appears. Letters are ignored throughout — only digits count, and a serial carrying no digits at all has a total of zero, which is even.

Releasing a Held Button

Holding the button lights a coloured strip beside it. The strip's colour dictates when the operator lets go: they must release while the required digit is showing anywhere in the countdown timer, minutes or seconds.

Strip colourRelease when the timer shows a…
Blue4
White1
Yellow5
Any other colour1
Timing note. The timer is read at the instant the operator releases, from the display on the panel. Call the digit as it appears, not as you predict it. A quick tap is anything under about a third of a second — a hold that short is read as a press, not a release.

The last digit here means the last digit, not the last character. If the serial ends in a letter, keep reading backwards until you reach a number. See Appendix A.

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IED Field Defusal Manual v. 1Simon Says

On the Subject of Simon Says

A children's memory toy, wired to something that is not a children's toy. The colour that flashes is never the colour you press.

A strike wipes your working. A wrong press at any point sends the module back to the first flash — and because a strike also moves you to the next row of the table, every translation you just made is now wrong. Throw the list away and start again from the new row. This applies to strikes from any module, not just this one.

Translate each flash into a press using the table that matches the serial number, on the row matching the current strike count.

If the serial number contains a vowel:

Red flashBlue flash Green flashYellow flash
Press:No strikes BlueRedYellowGreen
1 strike YellowGreenBlueRed
2 strikes GreenRedYellowBlue

If the serial number does not contain a vowel:

Red flashBlue flash Green flashYellow flash
Press:No strikes BlueYellowGreenRed
1 strike RedBlueYellowGreen
2 strikes YellowGreenBlueRed

Work it out before you speak. Take all four flashes down as they play, replay to check them, then translate the whole list against the correct row — and only then start calling presses. Half a list called out loud is how strikes happen.

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IED Field Defusal Manual v. 1Passwords

On the Subject of Passwords

Five letters. Six ways each of them could be wrong. Somebody's security policy was written on a napkin.

Method: read out all six letters of the first position only. Cross off every word in the list that cannot start with one of them. Move to the second position. Two positions is usually enough to leave a single candidate; three always is.

aboutafteragainbelowcould
everyfirstfoundgreathouse
largelearnneverotherplace
plantpointrightsmallsound
spellstillstudytheirthere
thesethingthinkthreewater
wherewhichworldwouldwrite

Watch for the near-pairs: their/there, these/three, still/spell. If two candidates survive, ask for a position they disagree on rather than guessing.

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IED Field Defusal Manual v. 1Keypad

On the Subject of Keypads

Whoever built this ran the entry code off the wiring loom to save themselves a second circuit. Sloppy, and the best news in this book.

Take the wire colours down first. The calculation needs the full colour list of both wire modules, top to bottom, including wires that have already been cut. Cut wires darken and become hard to call. Write them out before anyone reaches for the cutters.

Step 1: Wire weights

RedBlueYellow WhiteBlack
234 56

Step 2: Reducing

Every digit below is reduced before it is used: if a result is larger than 9, add its digits together and keep going until one digit remains. 24 becomes 6. 108 becomes 9. A reduced result is always between 1 and 9, which is why the keypad has no zero.

Step 3: The four digits

Call the wire module in the top-left slot module one, and the one beside it module two.

DigitCalculate
First Weight of the top wire on module one, multiplied by the weight of its bottom wire. Reduce.
Second Number of wires on module one multiplied by the number of wires on module two. Reduce.
Third Weight of the top wire on module two, multiplied by the weight of its bottom wire. Reduce.
Fourth The first three digits multiplied together. Reduce.

Worked example

Module one: red, white, blue, blue — four wires.
Module two: yellow, black, black — three wires.

The code is 6 3 6 9.

Only the top and bottom wires of each module carry weight — anything between them is ignored, and cutting a wire does not change the code. The fourth digit is a check on your own arithmetic: if the operator enters three digits you are confident in and the fourth is wrong, the mistake is in the multiplication, not on the device.

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IED Field Defusal Manual v. 1Appendix A

Appendix A: The Serial Number

The serial number is printed on the readout at the top of the defusal panel, beside the countdown and the status line. It is a mix of letters and digits, and it is the only piece of information on the device that more than one module cares about.

Take it down once, in full, before anything is touched. Have the operator read it character by character — letters phonetically, digits as numbers. Misheard serials are the commonest cause of a wrong wire, and a wrong wire cannot be taken back.

Four properties to work out immediately

PropertyMeaningUsed by
Last digit The final number in the serial, ignoring any letters after it. Odd or even. Wires, The Button
Digit total Every digit in the serial added together. Odd or even. The Button
Contains a 4 Whether the digit 4 appears anywhere at all. The Button
Vowels Whether A, E, I, O or U appears. Y does not count. Simon Says

Worked example

Serial KT4B7X. Digits are 4 and 7. Last digit is 7 — odd, so the wire rules that ask for an odd ending are in play. Digit total is 11 — odd, so the "Detonate" button rule does not fire. A 4 is present. No vowels, so Simon Says uses the second table.

Two easy mistakes. The last digit is not the last character — a serial ending in a letter still has a last digit further back. And a serial carrying no digits at all has a total of zero, which counts as even, and no last digit whatsoever — any rule asking for an odd last digit simply does not apply.

Closing Note

Three things end a device: all six modules green, a third strike, or 00:00. You control exactly one of those. Ask for colours, ask for counts, and make the operator repeat the instruction back before they act on it.

KEEP TALKING
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