I am not in a position to shed much light on why the C-802 was able to bypass Israeli defenses and strike their ship.
There are two main reasons for this:
1. I do not know how much of our technology Israel has available to it, in part because the relevant techology is still classified in US arsenals, and therefore also classified if sold to our allies.
2. A big part of the equation depends on the precise operational conditions onboard that ship at that point in time.
Discussion of, point 1:
The original Aegis system used its powerful radar to locate and track inbound missiles and aircraft, to track outgoing defensive ordinance, and to adjust the track of defensive ordinance to meet incoming threats.
Radar is a dual edged system, it gives away your position from further away than you are able to see. Under certain situations US doctrine requires Aegis to go dark, to cease illuminating the battlespace, so as not to give aaway the ship or battle group's position.
Because of the effect this EMCON situation imposes on fleet vulnerability, therr have been research and development towards creating a network of sensors and response platforms which allo for "distributed processing". A high value asset like a ship can go dark, while a low value and more maneuverable asset like a P3 Orion aircraft can use it's sensors to feed threat information to the ship via secure datalink, allowing the Aegis system to process the information without having to transmit.
Various pieces of these developments have been released to the open source domain, but the most recent ones, including operational capabilities, have not.
Further there have been significant updates in processing horsepower and threat response algorithms, as well as increases in the pohysical capability of fleet defense like larger and faster anti-missile launchers.Without knowing exactly what Israel has, it is hard to pinpoint failure, and you can be sure that any published specifications fall far short of operational reality. To publish all of your secrets would be folly.
Discussion of point two:
Whatever happened to that vessel happened under combat conditions. Under those conditions, the situation changes in milliseconds, and human response can lag behind. Rules of engagement determine what latitude commandersd have regarding their threat posture, and all of this is true in a perfect, and mythical, situation. In live combat, mistakes can add to this and without possession of the ship's log, which will at best only tell a fractional part of the story, it impossible to reconstruct the failure.
Without even this minimal information only conjecture and supposition is possible.
1. From memory, this class of cruise missiles is slow, old, and packs a powerful warhead. I believe they are sea skimmers, capable of approaches at ten feet ASL. From memory, the speed of these missiles is between 200 and 350 mph. With the ship 16 km offshore, 8 miles for approximate conversion, a 300 mph missile will traverse the distance at six miles per minute, a total of 1 minute 15 seconds. I do not believe this is enough time to boot up an Aegis system from a cold start. If Israel was using known Hezbollah TOEs, which do not include Silkworm era cruiise missiles, the ROE may have been based on the assumption that EMCON was a lesser risk than illuminating the ship's position against an enemy with neither aircraft nor cruise missiles.
2. Although a sea skimming missile at an altitude of 10 feet ASL will climb above a surface observer's radar horizon at a range of 65 miles, surface clutter can reduce detection range significantly. Naturally a ship's radar is not located at surface level, but the limitations can still apply. There are algorithms to differentiate between stationary clutter and mobile threats, but radar itself works so close to the noise levels that probability equations shoulder a large part of the processing load in identifying returns. Probability equations are what determine what happens when you flip a coin.
3. While a networked threat identification and defense system has significant advantages of a single asset system, distributed sensing, processing, and response impose unavoidable delays. In a combat environment, these delays an be magnified, as large numbers of radiators compete for limited electromagnetic bandwidth. The spectrum os further contested with a technically competent enemy, through spectrum denial efforts.
4. In a high threat environment, where many targets are aloft simultaneausly, any system has finite limits to how many threats it can analyze, track and define a response to, and response systems can be overloaded as well.
All all of these variables up, and you guarantee leakers, enemy missiles that get through even a llayerd defense. Layered defense systems are measured in terms of what percentage of leakers they allow, with zero being desireable, but rarely obtained.
I am certain that Israel will conduct an after action review in this matter, which may or may not be released publicly. If you want to learn more about what went wrong, give it a year, and then search Janes or other sites for "lessons learned" reports, with the identifying variables, and you may get lucky.
"I am not in a position to shed much light on why the C-802 was able to bypass Israeli defenses and strike their ship. "
It has already been reported that the anti-missile defenses were turned off because the captain did not know of a threat by missiles and because there were so many aircraft in the area.
http://www.freerepublic.com/focus/f-news/1666974/posts
I believe I read on another thread that the system was not turned on.
I've not heard anything about anti-missile missiles, like the Patriot that we heard so much about in the first Gulf War. Are they ineffective, or what?