Some info about black box

With any airplane crash, there are many unanswered questions as to what brought the plane down. Investigators turn to the airplane's flight data recorder (FDR) and cockpit voice recorder (CVR), also known as "black boxes," for answers. In Flight 261, the FDR contained 48 parameters of flight data, and the CVR recorded a little more than 30 minutes of conversation and other audible cockpit noises.

The cockpit voice recorder from the downed Alaska Airlines Flight 261, held by the robotic arm of the remotely piloted vehicle that retrieved it

These recording devices, which cost between $10,000 and $15,000 each, reveal details of the events immediately preceding the accident. In this article, we will look at the two types of black boxes, ­how they survive crashes, and how they are retrieved and analyzed.

The damaged flight data recorder from EgyptAir Flight 990


Although many of the black boxes in use today use magnetic tape, which was first introduced in the 1960s, airlines are moving to solid-state memory boards, which came along in the 1990s. Magnetic tape works like any tape recorder. The Mylar tape is pulled across an electromagnetic head, which leaves a bit of data on the tape. Almost all the black boxes used today contains solid state memory devices instead of conventional Magnetic tape devices. Black-box manufacturers are no longer making magnetic tape recorders as airlines begin a full transition to solid-state technology.



Solid state electronics used in Black boxes contains no moving parts and is completely crash proof (some times not!! that too when the particular plane crashs..!) Memory boards are located safely located inside crash-survivable memory unit (CSMU). In recorders made by L-3 Communications, the CSMU is a cylindrical compartment on the recorder. The stacked memory boards are about 1.75 inches (4.45 cm) in diameter and 1 inch (2.54 cm) tall.
(oh! thats very small..!). The memory boards have enough digital storage space to accommodate two hours of audio data for CVRs and 25 hours of flight data for FDRs.

Architecture:



Cockpit Voice Recorder:
In almost every commercial aircraft, there are several microphones built into the cockpit to track the conversations of the flight crew. These microphones are also designed to track any ambient noise in the cockpit, such as switches being thrown or any knocks or thuds. There may be up to four microphones in the plane's cockpit, each connected to the cockpit voice recorder (CVR). Any sounds in the cockpit are picked up by these microphones and sent to the CVR, where the recordings are digitized and stored. There is also another device in the cockpit, called the associated control unit, that provides pre-amplification for audio going to the CVR. Here are the positions of the four microphones:

* Pilot's headset
* Co-pilot's headset
* Headset of a third crew member (if there is a third crew member)
* Near the center of the cockpit, where it can pick up audio alerts and other sounds

Most magnetic-tape CVRs store the last 30 minutes of sound. They use a continuous loop of tape that completes a cycle every 30 minutes. As new material is recorded, the oldest material is replaced. CVRs that used solid-state storage can record two hours of audio. Similar to the magnetic-tape recorders, solid-state recorders also record over old material.


Flight Data Recorders:
The flight data recorder (FDR) is designed to record the operating data from the plane's systems. There are sensors that are wired from various areas on the plane to the flight-data acquisition unit, which is wired to the FDR. When a switch is turned on or off, that operation is recorded by the FDR.

In the United States, the Federal Aviation Administration (FAA) requires that commercial airlines record a minimum of 11 to 29 parameters, depending on the size of the aircraft. Magnetic-tape recorders have the potential to record up to 100 parameters. Solid-state FDRs can record more than 700 parameters.! On July 17, 1997, the FAA issued a Code of Federal Regulations that requires the recording of at least 88 parameters on aircraft manufactured after August 19, 2002.

Here are a few of the parameters recorded by most FDRs:

* Time
* Pressure altitude
* Airspeed
* Vertical acceleration
* Magnetic heading
* Control-column position
* Rudder-pedal position
* Control-wheel position
* Horizontal stabilizer
* Fuel flow

Solid-state recorders can track more parameters than magnetic tape because they allow for a faster data flow. Solid-state FDRs can store up to 25 hours of flight data. Each additional parameter that is recorded by the FDR gives investigators one more clue about the cause of an accident.

7 Reasons No One Subscribes to Your Blog

While the number of subscribers isn’t the only important blog statistic, no one wants to manage a blog that has 0 subscribers. After all, it’s not exactly a sounding endorsement of your content if no one chooses to follow it.

 

So, it all leads up to the big question—why isn’t anyone following your blog? There isn’t one simple answer to this question. That’s why I’ve come up with this list of 7 reasons no one subscribes to your blog.

 

1. Your Content Sucks- Okay, so this might sound a little harsh, but one potential reason for a lack of subscribers is your content just isn’t that great. Most of the time, poor content is a result of “me too” blogging. Some bloggers are happy to play it safe rather than stepping out and saying something new. Before you post, always ask yourself if the content adds value to your field. If not, rethink your topic or your approach to it.

2. Your Posts are Advertisements- I could have included this with the first reason, but it deserves its own section. Sure, the ultimate point of your blog might be to promote your brand, but you shouldn’t be writing posts that are nothing more than advertisements. Here’s why: readers won’t subscribe to advertisements. Who wants to read post after post about how great your company is? Again, it’s all about adding value. Self-promotional posts don’t add value, and they won’t get you subscribers.

3. Your Subscribe Button is Hidden- Assuming your content is great, another reason no one is subscribing could be that they don’t know how. Think of your “subscribe now” button as your blog’s call to action. If it’s hidden, no one will ever take the action you desire. Instead, feature your subscribe button in an easy-to-see location above the fold. By making it easy to subscribe to your blog, you give yourself a better chance of boosting your subscriber base.

4. You Don’t Optimize Your Posts- While you don’t want your blog to turn into a keyword-stuffed, useless content directory, you also don’t want to completely ignore SEO. The search engines love fresh content. Simply optimizing your posts for relevant terms improves the amount of traffic you receive, and it increases your chances of earning new subscribers.

5. You Post too Infrequently- I doubt I’m the only one who’s unsubscribed from a blog because they updated rarely. Not only does updating infrequently lose your readers’ attention, but it also sends the message that you don’t really care about your blog. And if you aren’t committed to your blog, how can you expect anyone else to be?

6. You Post too Much- Now this might seem like a contradiction to the above point, but let me clarify. Posting a lot is good if all of your posts are of high value. Unfortunately, many binge posts lack quality. It seems they’re published just for the sake of keeping the blog in the forefront of the readers’ minds. And no one wants to be bombarded with constant posts that aren’t great.

7. You Don’t Market Your Blog- A blog is just like any other property, you need to market it to get it the attention it deserves. You can’t just sit blogging away in your little world expecting readers to suddenly show up. You need to promote your blog through social media sites, guest blogging, linking out, commenting, and other techniques.