Most of us perceive airport security personnel, baggage handlers and airline cabin crews as harmless individuals. They are, after all, tasked to make our travels abroad as convenient and safe as possible.

A risk management expert, however, warned that even the airport security crew can be infiltrated by terrorists, and can cause harm to a huge number of passengers.

Former National Transportation Safety Board member Vernon Grose admitted that the United States' airport security is woefully lacking in necessary safeguards, even 14 years after the terror attack at the World Trade Center on Sept. 11, 2001.

"The crew can be infiltrated. Luggage handlers, the people who prepare the food or those who service the lavatories – the number of people with full access who could do us harm is shocking," Grose, the chairman of Omega Systems Group Inc., told WND.com.

"Anyone can smuggle in a device. It's a wide-open gate if they want to come in," he added.

Grose' views bolster a report by the Department of Homeland Security last June, which revealed that as many as 73 aviation workers employed by airlines and even ordinary vendors in the airport had alleged ties to terrorism.

The same report also highlights the Transportation Security Administration (TSA)'s weaknesses in screening airport personnel.

"TSA had less effective controls in place for ensuring that aviation workers had, one, not committed crimes that would disqualify them from having unescorted access to secure airport areas, and, two, had lawful status and were authorised to work in the United States," the report read.

"In general, TSA relied on airport operators to perform criminal history and work authorisation checks, but had limited oversight over these commercial entities.

Thus, TSA lacked assurance that it properly vetted all credential applicants," it added.

The issue of aviation security once again came to the public's attention after a Russian jet was recently downed by Islamic State militants over the Sinai peninsula in Egypt.

All 224 passengers aboard Metrojet Airbus 321-200 were killed after a local baggage handler at Sharm el-Sheikh International Airport in Egypt supposedly planted a bomb inside a soda can.