Culprits of Lockerbie a treatise Concerning the Destruction
Summary of working of barometric electrolytic capacitor-delayed bomb
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- Descent of aircraft before capacitor fully charged
- Aircraft quickly climbed again
- Aircraft landed before capacitor fully charged
- Scenario involving no malfunction on Pan Am 103A
- Conjectured process of malfunction
- The slide switch: bomb-maker’s awareness that capacitor might retain a charge after failing to reach full charge
- Fundamental contradiction between setting a short detonation time but leaving positioning of a small bomb to chance
- Heathrow the only viable choice for getting the bomb airside
- Short time to detonation and outboard positioning of the bomb rules out use of a stand-alone countdown electronic timer (MST-13)
- An alternative notion: deliberately crashing the plane on British soil
- 4. Targeting Israeli army mountain-top posts
- 5. Alleged provenance of the MST-13 printed circuit board fragment, PT/35b – and doubts (a)
- Four categories of doubt
Summary of working of barometric electrolytic capacitor-delayed bomb The way the bomb seized by the BKA in Autumn Leaves on 26 October 1988 was clearly designed to work was that it would be primed, or armed, by inserting a plug into a socket. When the aircraft climbed after take-off and the cabin pressure dropped to a predetermined level the barometric switch closed a circuit and caused a current to flow from 1.5 volt batteries to a capacitor. For as long as the barometric switch remained closed in consequence of the aircraft remaining above the requisite cabin altitude the current would continue to flow from the batteries and would charge the capacitor. When it reached full charge, say at around 30 minutes after the circuit was closed by the barometer switch, the capacitor discharged via a transistor to the detonator. Descent of aircraft before capacitor fully charged Suppose, however, that before the charging process was complete the aircraft descended and the cabin altitude dropped below the level required to keep the barometric switch closed. The flow of current to the capacitor would have ceased and the capacitor would no longer have been under charge. The charge accumulated hitherto would then gradually have dissipated, at a rate dependent on a variety of factors, principally the characteristics of the transistor through which it discharged, but also ambient temperature and component quality and age. It might have taken a matter of minutes or possibly even hours but it would not have discharged as a burst of current to the detonator. Aircraft quickly climbed again What might have happened if before landing the aircraft climbed again? If it reached the requisite cabin altitude the barometric switch would have once again closed the circuit to the capacitor, which would have begun to be charged once more. If it was still holding a residual charge when the charging process recommenced it would have taken that much less time to reach full charge and detonate the explosive. Aircraft landed before capacitor fully charged Suppose the aircraft landed after a flight during which it had been at or above the requisite altitude for less than the time necessary to keep the capacitor under charge before it could discharge itself to the detonator; suppose the bag containing the bomb was then transferred to another aircraft which duly departed. Depending on the lapse of time involved in the original descent, the time on the ground and the rate of pressurisation on the second flight the capacitor might still have retained a residue of charge from the first flight. Charging would have duly recommenced but the time to discharge and detonation might be less than it would otherwise have taken if the capacitor had fully dissipated its charge. Scenario involving no malfunction on Pan Am 103A Assuming the Lockerbie bomb was a PFLP-GC device of the specification seized by the BKA on 26 October, 1988, such a sequence of events could not have occurred if the device was functioning normally. This would have been for the simple reason that on the 78 minute flight from Frankfurt (see Gobel’s Zeist evidence, p.8792) the aircraft would have been above the necessary cabin altitude for significantly longer than the 38 minutes necessary to detonate the explosive. Conjectured process of malfunction This brings us to the mechanics of a possible malfunction and the possible sequence of consequent events. Suppose the bomb was smuggled aboard PA103A at Frankfurt with the terrorists intending (less ambitiously than to destroy a jumbo jet set to cross the Atlantic) that it should detonate on the flight to Heathrow. Suppose the barometric switch operated correctly but for some reason a faulty or temperamental capacitor or a circuitry problem caused it to fail to charge up adequately (or at all) and it therefore failed to detonate the explosive after the requisite time. Suppose at Heathrow the bag carrying the bomb was transferred to PA103 and by an extraordinarily remote chance was fated to be placed in the hold in a supremely lethal position. With the aircraft’s departure for JFK the barometric switch once again turned on the circuit when the cabin pressure dropped to 950mb. However, the partial charging experience on the flight from Frankfurt had somehow improved the temperamental capacitor’s performance characteristics and the fresh charge now nudged it into working properly. It is the possibility of initial malfunction followed by adventitous self-correction to which Feraday seems to have been alluding in his comments on Gobel’s report. This scenario would not of course have required the re-priming of the bomb on the tarmac at Heathrow since it would have remained armed. It could also explain the inconsistency between Gobel’s finding that the barometric switch in the BomBeat seized by the BKA at Neuss on 26 October 1988 would have turned on the current at 950mb after 7 minutes into the flight of a 747 on standard ascent and his “measurement” of the capacitor as providing for a delay of between 35 and 45 minutes. According to Dr Swire in personal correspondence with the author, the use of a transistor between the capacitor and the detonator would have been likely to cause the capacitor, partially charged at the point when the barometric switch turned off the supply of current from the batteries, to retain a proportion of that charge for a significant time afterwards. If, therefore, a malfunction had, for example, resulted in only a partial accumulation of charge in the capacitor by the time Pan Am 103A descended into Heathrow but on the bomb being transferred to Pan Am 103 proper function was restored the residual charge would have meant that the capacitor might well reach full charge in significantly less time than the range of 35 to 45 minutes to full charge cited by Gobel in his report on the seized BomBeat. A shorter time of 31 minutes, say, for the capacitor to reach full charge would exactly account for Gobel’s conclusion that the barometric switch in the seized BomBeat would have turned on the current at 7 minutes into the flight and the 38 minutes from take-off to detonation of the bomb over Lockerbie. The slide switch: bomb-maker’s awareness that capacitor might retain a charge after failing to reach full charge In his report Gobel described a miniature slide switch included in the capacitor circuit, which he assumed was used by the maker to discharge the electrolytic capacitor completely before re-testing the run time and setting it all in the resin. The opinion has been expressed to the author that this suggests the maker was aware that the capacitor might remain partly charged after a previous test and that it might remain partly charged after the first leg of a two-leg journey. The potential significance of this is that if the bomb was put on board Pan Am 103A the terrorists could have been aware of the possibility that the capacitor might fail on the Frankfurt/Heathrow run but might “pick up,” as it were, on a second flight. Might they perhaps have had such a second chance in mind and therefore had the the suitcase labelled for airside transfer to the transatlantic flight out of Heathrow as a long stop? The likelihood or otherwise of such a scenario is discussed later. Might the argument be applied by extension to smuggling the bomb on board a plane at Luqa, with the possibility in contemplation that this would have provided two further chances? Such a notion would be belied by an assumption that the terrorists were intent on destroying an American plane. 3. Manifest unsuitability of the MST-13 (a) Primary disadvantage of a simple countdown timer By contrast with the barometric trigger, the MST-13 is a simple countdown timer. The time can be set exactly to within a few seconds. However, wherever the device happens to be at that time it will explode, even if it is on the tarmac or a baggage store. Contrary to popular myth, PA103 left Heathrow on time, but it could easily have been otherwise for an evening departure from one of the world’s busiest airports during the immediate pre-Christmas holiday rush. Indeed, the flight almost lost its departure slot twice, the second time because of the late arrival of PA103A, the feeder flight from Frankfurt. Given the scope allowed by a simple countdown electronic timer for setting a detonation time long into a flight over the Atlantic the terrorists would hardly have chosen instead to incur the cumulative risk of delay and a relatively harmless detonation on the tarmac or, if the plane did happen to leave on time, bringing it down over land using a bomb wrapped in brand new easily-traced clothes with their labels still attached. (b) Reasons why the terrorists did not use an electronic countdown timer Fundamental contradiction between setting a short detonation time but leaving positioning of a small bomb to chance Concealment of the bomb inside a radio cassette player necessarily imposed severe limitations on the quantity of explosive. The relatively small amount of what was supposed to be Semtex contained in the radio-cassette player had a catastrophic effect only because the suitcase was positioned outboard in the baggage container and very close to the aircraft hull. It is implicit in the notion that the bomb suitcase was sent from Malta via Frankfurt to Heathrow with an electronic timer and no accomplice intervention at Heathrow that its positioning in the baggage container of Pan Am 103 had to be left to chance. Experienced and determined terrorists were hardly about to leave matters to chance but supposing – improbably – that in the case of Pan Am 103 they had been content to do so, this would have meant that if the suitcase ended up being stowed mid-hold the bomb might well fail to do sufficient damage to destroy the giant plane outright and might allow the crew to make an emergency landing. In the early 1970s there were two such lucky escapes following the planting of bombs by the PFLP-GC (February 1970: Austria Airlines flight from Frankfurt to Vienna, hole blown in fuselage at 10,000 feet; 1972: El Al flight from Rome to Tel Aviv at 15,000 feet; see Ashton, p.31). For that very reason and necessarily having to leave the positioning to chance, it would have been imperative to delay detonation until both of the following two stages in the flight had been reached: (i) the plane was well out over the Atlantic and beyond the possibility of being able, if merely crippled by the blast of a small bomb placed mid-hold, to return to or reach any convenient airfield; (ii) the plane had reached its cruising altitude of around 40,000 feet, that being the altitude at which the differential between the cabin pressure and the atmospheric pressure would have been at its greatest and at which therefore a small device placed mid-hold would have been capable of doing its greatest damage to the fuselage structure. Having the option to vary the detonation time afforded by an electronic countdown timer but nonetheless deliberately setting an early time for the explosion would have been incompatible with not being able to control the positioning of the bomb in the container at Heathrow. This is the fundamental contradiction involved in the contentions (a) that the suitcase bomb came from Frankfurt with only a very slim chance that it might be placed in the optimum position and (b) that it was set with only a short time to detonation after departure. The fact remains, however, that the bomb was placed in precisely the position in which it would have been most lethal at any height and was given a short detonation time (consistent with the use of a barometric trigger). The irresistible inference is that the terrorists did not leave matters to chance and did use a barometric trigger. Heathrow the only viable choice for getting the bomb airside In short, only at Heathrow could the terrorists hope to influence the placing of a small device in the container in a position close to the hull, an essential requirement for successful destruction of the aircraft if detonation was not to be delayed (which it was not) until it was far out across the North Atlantic and cruising at maximum (and most lethal) altitude. Even then there was hardly any guarantee that a mid-hold explosion would cripple the plane. With a relatively small quantity of explosive and detonation planned early into the flight out of Heathrow the optimum need to position the suitcase as close to the fuselage hull as possible meant that this could not be left to chance but would have required terrorist intervention at Heathrow. By a process of irrefutable logic this demonstrates conclusively that if an early detonation out of Heathrow was planned it would have been quite pointless setting out to send the suitcase from either Luqa or Frankfurt, where security was tight (and in the case of Frankfurt where a watch for Toshiba housed bombs was in force) rather than smuggling it into the system at Heathrow, where security was lax, if terrorist intervention to position the bomb was going to be necessary there anyway. If a short detonation time from Heathrow departure was planned, with intervention at Heathrow therefore necessary to ensure that the bomb was correctly placed in the outboard position and to preclude the possibility of the crippled aircraft surviving to make a safe emergency landing, the obvious choice for the terrorists was not sending the suitcase as unaccompanied baggage from Malta or Frankfurt but instead smuggling it into the airport at Heathrow. It was wholly pointless to risk interdiction at highly secure Luqa or moderately secure Frankfurt
Short time to detonation and outboard positioning of the bomb rules out use of a stand-alone countdown electronic timer (MST-13) Since, then, the suitcase had to be placed in exactly the right outboard position on Pan Am 103 to cause maximum damage and instant destruction there was every reason to introduce it into the system at Heathrow rather than sending it from distant Malta (or even Frankfurt). With the relatively small bomb placed in exactly the right position to cause cataclysmic damage there was no need to give it a long detonation time from departure. It would be destroyed outright and the proximity of a convenient airport to provide emergency landing facilities would be of no avail. It follows irresistibly that there was no point whatsoever in using an electronic stand-alone countdown timer for a short detonation time. The terrorist who planted the suitcase at Heathrow would not know how long he would have after his latest opportunity to set the timer and leaving the suitcase in position before the plane departed. There might be a long delayed departure or even a cancellation because of a serious technical fault. It might not be possible to wait until the last minute to plant it. In the circumstances a barometric trigger would have been the only sensible method of detonation (if it is not off-colour to apply a word such as “sensible” to the commission of such outrages as wanton mass murder). The use of a barometric bomb would have been a further reason for personally delivering the primary suitcase to the airside zone at Heathrow rather than sending it unaccompannied on a connecting flight. If flown in from Frankfurt on Pan Am 103A it would have had to be primed at Heathrow by an accomplice plugging in the main switch. This, again, is a good reason why dispatch from Malta or Frankfurt would have been utterly pointless. An alternative notion: deliberately crashing the plane on British soil? What of the idea that the plan was actually to bring the plane down on British soil in revenge for letting US bases here be used in the 1986 raid on Libya? Quite apart from the fact that even in our populous island most land remains open countryside (with the prospect of doing no more than “scaring a few sheep,” as it has been put to the author) the short answer is that the usual “Great Circle” route was west over the Irish Sea and neutral Ireland, the country whose IRA “freedom fighters” Gaddafi had been actively assisting with supplies of Semtex and armaments until the 1980s. In fact the flight was only diverted northwards because of bad weather. In any event, such a motive would hardly have outweighed the delay risk factor or the possibility of a safe emergency landing. (The assumption that the plane would take the Great Circle route and fall into the Irish Sea probably explains why the terrorists were untroubled by leaving traceable labelling on the surrounding clothes.) (c) Structural unsuitability of an MST-13 It is not only the inherent unsuitability of the MST-13 electronic timer which rendered it of little practicable utility for the particular job in hand. Its design and dimension also precluded it as a viable component. An example of the MST-13 which was photographed by the CIA in Senegal in early 1988 (as to which see later) was contained in a plastic housing measuring 80 x 75 x 52 mm (see Ashton, Megrahi, p.66). Another version, which came into American hands in Togo in 1986, was smaller, measuring 71 x 66 x 21 mm, was open-sided, permitting the innards to be seen. The well known “trial loading” photograph exhibited at Zeist shows the interior of a Toshiba radio-cassette player loaded with explosive material and an MST-13. The photograph perfectly illustrates the two specific reasons why the use of such a timer would have been wholly unsuitable. First, in preparing the trial loading technicians had to remove the timer from its metal casing in order to fit it in to the body of the Toshiba. The effect of this would have been seriously to undermine its reliability. Second, the Toshiba is shown with the recorder tape drive mechanism laid outside it, again because there was no room for both the specified quantity of Semtex and the MST-13. Leaving out the tape drive would have made the device particularly vulnerable to detection. It would have been very easy to spot when passed through an x-ray machine. By contrast, the pressure switch and simple capacitor delay timer used in PFLP-GC devices were much more compact and would easily have fitted into a radio-cassette player without removal of its components. It should additionally be observed that removed from the relative protection of the casing the PCB would have been even more likely to have been totally obliterated by the Semtex blast two inches away (as to which see further below under sub-caption 5(d)). 4. Targeting Israeli army mountain-top posts It may be concluded beyond any sensible measure of doubt that the bomb which destroyed Pan Am 103 must have been detonated by a barometric pressure trigger of the kind used in typical PFLP-GC devices. The fact that adherents to that organisation were found in possession of such devices shortly before Lockerbie is reason enough to assume that they intended to use them against commercial airliners. What conceivable other use might they have had? Ahmed Jibril, founder and commander of the PFLP-GC, came up with an explanation. Speaking to camera in Allan Francovich’s 1994 documentary The Maltese Double Cross (ref: 37 mins of 2hrs 35 mins) he asserted that the barometric pressure trigger was for use in destroying Israeli army bases on the tops of mountains. By 1988 Israel no longer controlled the Sinai Peninsula with its celestially proximate summit of Mount Sinai at 7,497 feet above sea level, and its neighbour, Mount St Catherine standing at 8,625 feet. Mount Hermon, in the part of the Golan Heights retained by Syria, stands at 9,232 feet but a neighbouring peak of 7,336 feet is the highest elevation in the Israeli controlled sector of the region. This is far higher than the 1,625 feet necessary to activate a basic barometric switch of the type used by the PFLP-GC in the Toshiba BomBeat device seized by the BKA at Neuss on 26 October, 1988. (It will be recalled that Rainer Gobel had found that it would switch on the circuit at 950mb, the atmospheric pressure at that moderate altitude.) We have already conjectured that the 750mb marking on the barometric switch in the seized BomBeat may have represented the minimum pressure to which the switch was capable of being adjusted and that it could therefore potentially operate at up to 2,500 metres (8,125 feet, the altitude at which the normal atmospheric pressure is 750mb). Assuming that it could be so adjusted it could in theory have been used for the purpose Jibril claimed but it is far from clear how he purported to envisage that a barometric bomb might be used. Would it be smuggled on board an army helicopter ascending to the post or in an army vehicle, assuming that there was road access to the highest peaks? One wonders whether it might not have been simpler to target the positions with SAM missiles, of which Syrian forces had a large arsenal. Perhaps Jibril was being provocative and had no intention of being taken seriously. It seems he may have been inspired by the claim made to the BKA by his henchman Hafez Dalkamoni when under interrogation following his arrest on 26 October 1988 (see Emmerson and Duffy, The Fall of Pan Am 103, supra, p.210). Dalkamoni was unable to provide a convincing explanation as to why the bombs had to be manufactured in Europe for use in the Middle East. 5. Alleged provenance of the MST-13 printed circuit board fragment, PT/35b – and doubts (a) Existence of doubt AAIB suspicions We have seen that Peter Claiden, the senior AAIB investigator, doubted that the fold in the AVE4041 data plate could have been caused by the explosion. Further, he was unable to suggest a trajectory of travel which the Toshiba PCB fragment, exhibit PT/30, may have taken from the suitcase to the data plate in the fold of which he found the aggregate material, AG/145, containing the fragment. These problems have induced serious doubts about the provenance of AG/145. The suspicion that it was planted can hardly be ruled out. Four categories of doubt Quite aside from the inherent, fundamental, improbability and implausibility of a stand-alone electronic timer having been utilised in the job of detonating the Pan Am 103 bomb various doubts on provenance, similar to those voiced by Claiden on AG/145, have been cast on the official story of the provenance of PT/35b, identified as the fragment of a PCB from an Mebo MST-13. The doubts fall into four distinct categories:
(b) The official story summarised Found wedged in the blast-damaged collar of a Slalom shirt The official story presented at Zeist on the discovery of PT/35b was this. On 13 January, 1989, two detective constables were sifting through the enormous collection of small debris items in store at the Dexstar warehouse in Lockerbie when they came across a charred piece of grey cloth which had been picked up off the ground in open countryside over twenty miles away. It was allocated the number PI/995 and a label signed by the officers was attached to it. The charring indicated it had probably been in close proximity to an explosion and so on 8 February, along with numerous other items of debris, it was forwarded to RARDE where a week later it was briefly examined by Dr Thomas Hayes, who earmarked it for further scrutiny. RARDE were carrying an enormous workload and it was not until 12 May that Dr Hayes came to examine the cloth in detail, producing a sketch and notes. Confirming it was blast-damaged he noted that it was possibly a shirt collar and, as we have seen, the RARDE scientists eventually concluded it was from the grey Slalom brand shirt which they decided had been in the Samsonite hardshell suitcase containing the bomb. From the cloth Hayes extracted a scrap of paper, some fragments of black plastic and, allegedly, the green “fingernail-size” fragment of a PCB. Collectively the extracted items were given the reference number PT/35, with each of the items being given an alphabetic suffix, so that the PCB fragment became PT/35b. Subsequently, as we have seen, Anthony Gauci suddenly and belatedly professed to remember selling two Slalom shirts one of which, he claimed, matched the shirt neck material. Directory: docs docs -> Application for acem docs -> Observational Assessment of Teaching Practices Teaching Assessment Initiative Proposal Submitted to The Teachers for a New Era project docs -> Traditional British values docs -> From Warfighters to Crimefighters: The Origins of Domestic Police Militarization docs -> Borzoi Club of America Register of Merit Program I. What is a Register Of Merit docs -> Protecting the rights of the child in the context of migration docs -> United Nations E/C. 12/Esp/5 docs -> 9th May 1950 the schuman declaration docs -> Getting To Outcomes® in Services for Homeless Veterans 10 Steps for Achieving Accountability Download 0.96 Mb. Share with your friends:
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