When a plane hit the Pentagon on Sept. 11, 2001, Capitol Police officials didn’t know if another plane was on its way to the Capitol.

Unlike today, they weren’t in constant contact with federal agencies such as the FBI, the Secret Service and the Department of Defense. They had no standard protocol for evacuating the Capitol when an airplane was on the way to wreak havoc. Their force was small, their radios were outdated, and their world was insular.

“The protocol then was not an established protocol. It would be as you saw what happened,” House Sergeant-at-Arms Bill Livingood said in a recent interview. “We did not know an aircraft hit the Pentagon until it hit.”

Seven years later, law enforcement at the Capitol — and across the nation — has matured.

When the Secret Service identifies a suspicious vehicle in Washington, D.C., Capitol Police officials know it. If a plane enters restricted airspace, one of dozens of pre-scripted plans go into effect.

While the events of 9/11 put all those changes into action, its anniversary isn’t necessarily more dangerous than any other day. Terrorists “aren’t as tied to anniversaries as we are,” Senate Sergeant-at-Arms Terrance Gainer said.

Still, Capitol Police Chief Phillip Morse said officers will be ready at posts clearly visible to the public.

“It’s a day of mourning and remembrance. It brings back a lot of the fears and realities of the world that we live in,” Morse said. “We’ll just be more visible to make people feel more comfortable.”

Morse also pointed to several security improvements made over the past year, including a revamped screening process and a reinforced presence at the “access points” to the Capitol.

Officers are now trained to recognize certain disguised weapons and are more proactive, Morse said. They have practiced evacuations on the Capitol grounds and go through more training than ever before.

But there’s still work to be done.

The police union has complained of low morale among officers under Morse’s leadership, and Members continue to monitor the department’s troubled administrative departments.

Just two months ago, police officials asked 15 recruits to resign after realizing they didn’t pass background checks.

If “we find that there’s holes and that there’s lessons learned, we shore up the holes. We retrain if necessary,” Livingood said, adding that such problems don’t hinder the department’s ability to handle emergencies.

Emergency plans still don’t go exactly as planned, however. In March, a “Code Orange” alert — meaning an airplane had entered restricted air space — prompted an uneven evacuation.

A Code Orange does not necessitate an evacuation, yet some Members and staffers left the building on the advice of officers and after a public announcement by Senate Majority Leader Harry Reid (D-Nev.).

Since then, Capitol Police officials say, they have fine-tuned the process. However, some have criticized Congress for the lack of a single point of command in a crisis.

In the House, for example, the Sergeant-at-Arms is responsible for evacuation while the Chief Administrative Officer handles the continuity of business.

On the Senate side, the Sergeant-at-Arms is in charge. And both chambers are under the three-person Capitol Police Board, made up of the House and Senate Sergeants-at-Arms and the police chief.

Livingood said the system works. Gainer agreed, but added that it isn’t ideal.

“The bottom line is we’re linked,” Gainer said. “It is not as crisp as I think I and others would like it to be, with a single line of command. … But we’ve made it work.”

Gainer also mentioned an effort to get Congressional leaders to update a “leadership agreement” that describes how the Capitol Police Board and the department should handle emergencies.

He declined to get into specifics, saying only that he’d like it to be “refreshed.”

At this point, emergency plans call for the board to make decisions, and officials say that the department is ready with a flurry of prepared and vetted plans for any situation akin to 9/11.

“We would have to have a very strict control of the environment,” Gainer said. “I’m suspecting we would stop tours, close some streets, while we and the larger Washington area are assessing what the threat is.”

But Livingood noted that one thing hasn’t changed in seven years: the pride and loyalty of Capitol Police officers.

On Sept. 11, 2001, after officials had evacuated the Capitol and determined that a terrorist’s plane may have been headed their way, Livingood tried to convince three officers to leave the building with him.

They insisted on staying.

“I think you find that people today realize the dedication of the U.S. Capitol Police and appreciate that they’re willing to lay their life on the line for everyone here and in the community,” he said. “That’s what gives me great pride.”