Air hijackings give publicity
Militants resort to plane hijacking because of two reasons. First is the publicity, which such an act generates; and the second is the growing attraction of terrorists to 'soft' targets since many high-profile targets have been 'hardened'.
Militants resort to hijacking of planes because of two reasons. First is the publicity, which such an act generates; and the second is the growing attraction of terrorists to 'soft' targets since many high-profile targets (military and diplomatic institutions) have become difficult.

Even this selective list makes several observations possible. Firstly, no state, regardless of its status in the international system, is immune to terrorist activity. Therefore, in order to delineate any comprehensive strategy to combat international aviation terrorism, states must work within multilateral forums, which have the ability to operate and transfer information at a supra-national level. The very nature of the aviation industry renders traditional national-based strategies anachronistic.
Secondly, the sheer magnitude of the problem is much greater than present efforts at security would tend to suggest. Although the risk of injury or death is far greater from road accidents or violent crime than air travel, the latter is the site of a significant proportion of international terrorist activity. In fact, as Paul Wilkinson demonstrates, in 1989 deaths caused by terrorist attacks on civil aviation accounted for 70 per cent of the fatalities from international terrorism in all its forms.'
Given the seductiveness of civil aircraft as terrorist targets, the international community should give aviation security the priority it so obviously warrants.
Finally, when assessing the casualties of air disasters, the list of victims almost entirely constitutes of civilians. This may indicate that the desire of terrorist organisations to limit their campaigns to high-prestige targets is waning. Instead, tactics, which result in maximum carnage and generate maximum publicity seem to be preferred; and in scenes of carnage it is usually the innocent who are the first victims.
For whatever reason, be it revenge, politics or otherwise, the history of the aviation industry is littered with examples of what some may choose to call victories of terrorism and others may denote as lapses in aviation security systems.
The inserted unaccompanied bag: Usually displaying an interline routing tag the bag is introduced to the baggage stream by either airport staff or baggage handlers. It was allegedly this method which the two Libyan suspects employed to insert the bomb which destroyed flight PA 103 over Lockerbie.
The disappearing passenger unaccompanied bag -- usually tagged for an interline route with at least two airports. This occurs when a passenger fails to report for the subsequent leg of an interline route. However, the passenger's pre-tagged baggage is nonetheless transferred to the next outgoing flight on the itinerary. If the passenger checks-in but does not board the outgoing flight this is called a "gate no show".
The unwitting accomplice: A passenger is duped into carrying an illegal item in their cabin or hold baggage. In some circumstances passengers may opt to pool their baggage in order to avoid excess charges. This has a similar effect.
The suicide bomber: A passenger knowingly carries an illegal item within their cabin or hold baggage.
In practice IEDs have been infiltrated into both airline baggage and cargo systems. Until the 1990s systems to ensure cargo security were noticeably underdeveloped. Airlines that had spent large sums of money to security-screen passengers and their baggage were content to carry tons of unscreened cargo on the same aircraft. Indeed, such an omission has been utilised by Columbian drug traffickers among others to pedal their illicit cargo. If drugs can be smuggled aboard aircraft cargo, what is to prevent explosives travelling in a similar fashion, as was the case in the destruction of the Air Lanka Tristar in 1986?
As long as cargo security remains a secondary concern amongst airline security programs terrorists are bound to exploit any potential weaknesses, for example, shipments of mail. The record of aviation history reveals that while cargo security is indeed a potential liability, in practice passengers and their baggage remain the major security threat to airlines. While passenger and hand-baggage screening represents the most visible aspect of airline security to the travelling public it is by no means infallible. In this process Xrays and open searches (of a recommended 10 per cent of all hand baggage) form the basis of the security system. However, both the TWA (2 April 1986) and Korean Air 858 (29 November 1987) airline bombings resulted from IEDs taken aboard the aircraft in handbaggage. More generally, this process also suffers from the fact that, put bluntly, the larger the bag the less likely one is to discover anything.