So I just watched Olympus has Fallen and I realize it is a fictional story. Slight spoilers for that movie in this question.
What type of defense systems exist for the White House from aerial and ground assault? In the movie, a C-130 gunship flies towards the White House, shoots the two fighter jets that are initially sent to escort it away, then proceeds to go to town on the the White House itself and a bunch of neighboring areas. I would expect there to be more aircraft on ready to repel a C-130. In addition, I would expect there to be more anti aircraft guns and missiles able to be deployed well before the plane is able to attack the White House. Is it realistic that a single C-130 could do that much damage?
Then there is a ground assault. Maybe 1-200 people coordinate a charge basically blowing up the fence around the perimeter and charge in, shooting everyone and two garbage trucks with miniguns mounted mow through everything. Could hundreds of people simply overwhelm the defense forces there?
The Secret Service has a policy of not commenting on security matters. (They have the word secret in their name, after all.) So I don’t know if you’ll be able to dig up anything other than speculation.
I am pretty sure the (A)C-130 gunship has limited or no capacity for air to air targeting, especially so against a modern fighter. So if the movie plot hinges on the assault gaining and maintaining air control via use of the gunship I think it has fallen down already.
Additionally whilst the secret service may not have the capacity to repel a large military-level attack, I am sure there are military assets that would completely wipe the floor with a couple of converted garbage trucks based quite nearby - attack helicopters? There are a number of US military bases quite nearby, and I know that just from having looked at a google map of the area in the past. I’m sure there is way more nearby than meets the public eye.
We regularly (once every couple years) have large scale counter terrorism drills incorporating the use of special forces and helicopter urban deployment in my remote city - I daresay there are heaps more exercises planned and conducted in the DC area and the response would be rapid and slick.
I assume that the President would already have been put into a panic room due to the unidentified military aircraft headed his way, but if not, certainly within a minute or so of explosions on the perimeter.
You have Stinger missiles, .50cal machine guns w/tracking system, F-16s, helicopters, .50cal sniper rifles, and modified AARAM missiles in the general area. You have quick reaction civilian and military forces in various states of alert. Also available are Bruce Willis, Captain America, and other action stars and superheroes who have asked not to be publically identified.
As noted above, an AC-130 would not be capable of taking out one or multiple fighters unless they just poked alongside with big “shoot me” signs. The cannons (20mm, 40mm, 105mm) would do a number on the exterior of the White House but the subterranean sections would be unscathed for the short time the gunship would continue to exist.
Here is a fairly detailed article that appears to be reputable. There almost certainly are SAM batteries at the White House itself and SS agents are reported to be armed with Stinger missiles on the roof. However, a couple of Stinger missiles isn’t going to take down a C-130 on final approach to attack the White House. They might work for small planes but the overall defense system is more distributed than just the local assets.
"Over the last decade, a Hummer-mounted point air defense system that uses FIM-92 Stinger missiles and a 50 caliber machine gun, known as the Army’s “Avenger” system, has become a common place fixture in and around Washington DC. This is true especially during times when the country is on high alert and they’re hard to miss.
Look a little closer and you’ll see the Avenger system is actually hard-mounted to the tops of buildings in key strategic areas around the city. This includes at least one Avenger turret overlooking the White House at a nearby building."
What does the guy in the ultralight DO in between landing at the Capitol, WH, or whatever and getting filled full of lead? I think you need something bigger to be a significant concern.
Both the U.S. Capitol and the White House are vulnerable to sudden attacks from rogue aircraft. The airspace directly above them is among the most protected in the world but that doesn’t mean much for a determined person that has control of an airliner. Reagan National is a major airport very close to all of the government centers.
I was surprised when I was making a connection through Reagan a couple of years ago how low and slow the approaches are from certain angles. I was sitting on the side of the plane that allowed for the best sightseeing and it was obvious that the pilots were threading the needle to stay out of heavily restricted airspace but it is striking that certain approach paths would be almost indefensible.
Just look for the Washington Monument, the tallest and most distinct structure in the general area, and you have clear and direct lines to the White House, Capitol and everything else. I am not sure how that threat can be protected against. Even effective Surface to Air Missiles can’t guarantee that they can bring down an airliner or military aircraft within a few miles. Even if a threat was shot down, it would still come down in a heavily populated area.
Ground attacks are much easier to defend against. Most people don’t realize it but the current White House is not a historical building. It was was completely gutted and rebuilt in the early 1950’s from the inside out. That reconstruction happened during the early parts of the Cold War. The details of the exact architecture are classified but it is generally known that there is a large bunker underneath it meant to house key members of government in case of a nuclear war for extended periods of time. There are probably also a series of tunnels that connect it to other government buildings. Any ground threat would just mean that the POTUS and family could secure themselves in the secure bunker until the appropriate evacuation plans were put into action.
A couple of Stinger missiles could certainly take down a C-130 but not reliably and quickly enough to neutralize the threat to the White House for one that is deviating suddenly from its flight plan let alone a larger airliner. C-130’s are extremely rugged aircraft by proven design and hitting them in the engines (which Stinger missiles are designed to do) would be ineffective to prevent any type of suicide mission because the last few miles to target would still likely be somewhat controllable. Stinger missiles are hand-held SAM’s and not very large. While they can certainly disable even large aircraft, they will generally not cause them to explode and drop from the sky.
Despite the extremely restricted air space over the White House and the Capitol, there are allowed corridors for many different types of aircraft just minutes away so the effective difference is minimal.
My definition of a “small” aircraft is one under 12,500 pounds.
My cousin is a Special Agent with the FBI. He spent most of Sept 11, 2001 on a rooftop in Washington, D.C. with a Stinger at his side. Then he spent the next couple of days at an undisclosed secure location as part of the VPOTUS entourage. I don’t know if he had the Stinger with him them. I had No Need To Know, so I never asked.
It’s not clear from the movie where the AC-130 took off from. It apparently appeared very quickly. And yes, the tailing two fighters were directly on the side of it for some reason that seemed odd. And after they were shot down, it took over 4-5 minutes for other response aircraft to be on site. I found that unbelievable.
After that, it took over 15 minutes for ground personnel to arrive. That seemed unbelievable too.
While the president did get to the secure bunker, spoiler - they had a mole in the bunker too.
It was a very entertaining movie But the AC-130 and the hundred of ground personnel seemed far fetched.
Individual SA-2 and SA-7 shoulder launched missiles downed AC-130 gunships in the Vietnam war. A single Strela-2 brought a 130 down in Desert Storm. All crews were lost.
You must have been typing while I posted. 
But the AC-130 and the hundred of ground personnel seemed far fetched.