Jud Burkett, Associated Press
An aerial view shows the St. George Municipal Airport Tuesday, July 17, 2012.

A lot of questions remain to be answered surrounding the attempted hijacking this week of an empty SkyWest Airlines jet in St. George. Chief among these is how Brian Hedglin, a pilot whose access card had been deactivated after his girlfriend was found dead, was able to get onboard, defeat security systems and start the plane before crashing it while on the ground and then apparently killing himself with a gun.

Authorities now are beginning to wonder aloud whether perimeter security systems are adequate at airports, particularly small ones. The answer to that question is a resounding "no," but the remedy is neither easy nor cheap. In the post-9/11 world, Americans have to decide where best to focus energies in securing transportation systems and centers.

Yes, the Federal Aviation Administration could begin requiring high-powered radar equipment to constantly monitor perimeters at every airport. That would come at a cost that would either be reflected in landing fees or, ultimately, the cost of airplane tickets. And if the rule applied only to airports that offer commercial passenger flights, it would do nothing to thwart terrorists or others who might commandeer aircraft at any of the thousands of small airports or landing strips that cater only to private planes.

This week's tragic story in St. George coincided with a report from The Associated Press that U.S. citizens who land on the federal "no-fly" list because they may pose a terror threat are not prohibited from taking flying lessons. Foreign nationals are screened against the list before they can receive training, but U.S. citizens are not screened until they have been trained and are applying for a pilot's license. The 9/11 terrorists learned how to fly at American flight schools.

To close this loophole also would take money. Judging from the angry reaction to the story by several lawmakers, that may happen.

But other vulnerabilities remain, most notably regarding train travel, mass transit and the shipping of cargo.

The backdrop to all of this is a new State Department warning that went out this week concerning the continuing threat of terrorist acts against U.S. citizens and interests worldwide. The nation's enemies certainly haven't given up, despite heavy losses.

It would be easy to overreact to isolated incidents. No one has suggested Hedglin was a terrorist. By all accounts, he was distraught. He remains the principle suspect in his girlfriend's death. What happened in St. George was virtually unheard of, which is why it has become such big news.

Certainly, it is appropriate to seek answers to questions and adjust security measures that were compromised. SkyWest needs to evaluate how Hedglin got onboard and why the airplane was accessible. The airport, and even the FAA, need to examine whether greater perimeter security at all such airports would be appropriate and cost-effective. And governments and private businesses nationwide need to continue to examine how best to protect their clients and citizens. The answers won't be easy. Providing total security everywhere, however, is simply not practical.