In the US, President George Bush quickly came to the aid of his own ailing aviation players stumping up a US$15 billion Government bailout.
Initially business travellers stayed put. But they are now accepting of three-hour check-in times.
Another terrorist attack would severely damage world aviation travel. But security is tighter on most international flights.
Air New Zealand is pulling through but its future depends on a confident travelling market.
* Insurance
Many insurers were forced to rethink whether they could afford to cover terrorism risks.
Many European and London-based insurers will now cover only limited risks - at a vastly increased price. International brokers are having to come to grips with dealing with customers on the other side of the world. Governments do not want to provide backstop cover against terrorism and many underwriting decisions are being taken out of local insurer's hands.
In this environment some companies may decide to carry some of the risk themselves - covering up to five per cent of a $20 million insured sum through claims deductibles. In this case the claim must exceed more than $1 million before the insurer pays anything.
But the equations are tricky. Going unhedged might be a better option trading off the premiums saved against future excesses paid.
The World Trade Centre disaster has also reduced the global industry's risk capacity. Insurers have incurred multibillion dollar losses increasing the pricing pressure. Offshore reinsurers have to make a return on capital after sustaining large losses.
Ironically, a terrorism attack such as that on the World Trade Centre does not factor high on offshore reinsurers' risk categories. The potential for a major earthquake, or infrastructural disaster is identified as a higher risk.
Offshore risk assessors say crippling a nation's infrastructure - its telecommunications, electricity dams, roads or water supplies - is a more simple way for a terrorist to bring a country to its knees than trying a repeat performance of the September 11 flights.
Companies in those sectors - rather than the owners or residents of flash high-rise offices - have more to protect.
* Security
Pinpointing just which companies face security risks is difficult. There is no way firms can easily prepare against terrorist attacks without descending into an unworkable paranoia.
The Government will pay almost $14 million a year by 2003-2004 to ensure New Zealand makes an effective contribution to the international counter-terrorism effort. The $14 million will be spread across the defence, intelligence, customs and immigration portfolios.
It is concerned New Zealand could become a safe haven for terrorists and their activities. Legislation to stop financial flows to terrorist organisations is also being passed.
But businesses must now grapple with an environment where information is less secure. The Government has increased its power of surveillance - also grappling with new security issues. The trade-offs involve civil liberties and the potential disclosure of price-sensitive confidential information. Protecting employees and computer data is not simple - more background checks, more security guards, encryption technology - all take money and time.
* Bioterrorism
Anthrax was the big scare factor in 2001. Until September 11 hardly anyone had heard of it, let alone got down to the tricky business of identifying the particular white powder. In reality, Anthrax is not a major risk to New Zealand. But we are vulnerable to other biosecurity risks such as foot and mouth disease. A terrorist with economic sabotage on his/her mind would take a different route.
Six months on, the markets are still weighing the long-term consequences. Retail spending and hotel bookings are recovering. Downtown Auckland has filled up again. Restaurants are bubbling and confidence is high.
Global brands like McDonalds, Microsoft and Starbucks are still seen as vulnerable because they are seen as agents for globalisation. But the overall threat has diminished.
