Utopia, you are standing in it!

In 1977, William Landes published a classic study of crime and punishment. He investigated what happened to the number of hijackings in the USA after mandatory screening of passengers and their carry-on luggage was introduced in 1973.

During the peak period of hijackings, 1968 to 1972, the probability of apprehension the hijacker was 15%. For those hijackers that were caught, their average prison sentence was 30 years in 1972 to 1974. One quarter of hijackers were committed to mental institutions. Hijackings became so common that:

[a]irliners carried approach plans for the Havana airport and crews were instructed not to resist hijackers. There were also standard diplomatic procedures for obtaining the return of planes and passengers

No hijackers were killed during the course of their crimes until 1971. After that, there is about a 10% chance of the hijacker being shot dead. Air marshals started riding on US planes in 1970;  there were about 1200 of these  air marshals, who had to be about the most boring job in the world.

The primary purpose of hijackings in the USA in the late 60s and early 70s in the USA initially was to obtain free transport to Cuba for the political purposes or to avoid prosecution for crimes. However, in the early 1970s, this demand for air transport started to decline as news filtered back about how poorly these hijackers were treated in Cuba. A few of these hijackers chose to return to the United States.

Interestingly, the substitute for flying to Cuba was para-hijackers. They demanded a ransom of an average of $300,000 and then parachuted out of the plane.  One out of 18 succeeded. Their average prison sentence for the 11 that survived was 43 years.

As the table above shows, the number of hijackings in the USA  immediately fell from over 20 per year, with a maximum of 38 in 1969, to one or two per year after the introduction of mandatory screening of passengers and their carry-on luggage In 1973.

All hijackers were apprehended between 1973 and 1976. Apparently, hijackers  of all breeds and political complexions do not enjoy the prison experience. Criminals don’t like to be caught.

Interestingly, lunatics could be deterred. They retained sufficient capacity for planning to abandon their plans to hijack a plane because of the inevitability of arrest at the boarding gate after the metal detector sounded off from 1973 onwards. Only to the 12 offenders that were apprehended for attempted hijacking between 1973 and 1976 were committed to mental institutions. The remaining 10 were just plain stupid.

If lunatics cannot be deterred, do not respond incentives, they should  have continued to hijack planes at the same rate as prior to the introduction of mandatory screening in 1973.

That said, mandatory screening was not cheap, which may explain why airlines and their passengers were putting up with up to 40 hijackings per year, as Landes explained using 1977 dollar, which was back when a dollar actually bought something:

Although the mandatory screening program is highly effective in terms of the number of hijackings prevented, its costs appear enormous.

The estimated net increase in security costs due to the screening program (which does not include the time and inconvenience costs to persons searched) is $194.24 million over the 1973 to 1976 period.

This, in turn, translates into a $3.24 to $9.25 million expenditure to deter a single hijacking. Put differently, if the dollar equivalent of the loss to an individual hijacked passenger were in the range of $76,718 to $219,221, then the costs of screening would just offset the expected hijacking losses.

I should add, however,that air travel was much more expensive and much less frequent in 1973. The jumbo jet had only been introduced two years previous. Air travel is much more frequent these days so would the contemporary travelling public be willing to put up with the equivalent of hundreds of hijackings per year?

Caption: A Northwest Orient Airlines plane that was hijacked on July 1, 1968, is pictured at the Miami International Airport after returning from Cuba.

What did happen after the crackdown on hijacking  was the terrorists change tactics.  Embassy takeovers another type of sieges surged. Prior to the crackdown on hijacking, these were rare.

When embassies became fortified, the terrorists instead started kidnapping or murdering diplomats after they left the Embassy compound. As Walter Enders and Todd Sandler found

The existence of complements and substitutes means that policies designed to reduce one type of attack may affect other attack modes.

For example, the installation of metal detectors in airports reduced skyjackings and diplomatic incidents but increased other kinds of hostage attacks (barricade missions, kidnappings) and assassinations.

In the long run, embassy fortification decreased barricade missions but increased assassinations.