Has airport security measurably improved since September 11, 2001? What measures do you believe could be implemented to reduce costs and offer effective solutions?

Here is some information that you might include in your essay. Two months after the September 11, 2001, attacks, Congress passed the Aviation and Transportation Security Act (ATSA), forming the Transportation Security Administration (TSA). This effectively put the system of airport security under federal authority; formerly, each individual airport had control over its security and often hired private companies to carry out security operations. In November of 2002, the TSA was placed under the newly formed Department of Homeland Security.
The TSA carried out several reforms to improve airport safety. For example, passengers were not allowed to pass through security checkpoints unless they had tickets, and there were restrictions on what kinds of baggage they could bring on board the plane (and liquids, except in small quantities, were banned from passing through security). In addition, passengers were over time required to remove their shoes, and they were screened carefully. Cockpit doors were locked, and no one could enter the cockpit during the flight. These measures improved a situation in which there was lax airport security and little to no security measures during flights. Eventually, the TSA employed 65,000 federal employees, and passengers paid for some of these new expenses with a new fee added to their tickets, amounting to over $2.9 billion in fees from 2002 to 2010. According to an article in the International Business Times on September 11, 2014 (see the link below), some experts such as Victor Asal, a political science professor at SUNY Albany, think we are safer as a country than we were before 9/11. 
However, training and turnover at the TSA continue to be problematic. In past years, turnover among TSA employees was estimated to be 20-26%. That means that about one quarter of TSA employees left their jobs or were let go each year. In 2008, the TSA already had had 110,000 employees in six years, meaning that each year, they had many new employees and were in constant need of rehiring. In 2016, the TSA opened a new training facility in Georgia that will try to train TSA workers in the types of situations they will face on the job. This seems like a good step after a sting operation conducted by the Homeland Security Department found that many security checkpoints failed tests of their safety. Other measures to improve airline security might include more intensive training and continual checks to make sure airport security personnel are doing their jobs correctly. If screeners knew that there are routine tests, which would not be expensive to conduct, they might be more attentive to their jobs. In addition, perhaps personnel who met high standards could be used to train newer employees. 
https://www.ibtimes.com/911-anniversary-are-we-safer-now-september-11-1684730

https://www.pbs.org/newshour/world/911-to-now-ways-we-have-changed