Merry X-mas!
From CrossingTheSkies staff, we wish you a nice and merry christmas, and a happy new year also! We hope you found this blog beautiful, and we thank you all for visiting it!
We expect a new year (2009) with plenty of new and fresh material, new posts, aviation news, aeronautics and some more.
See you around!
Andrew && Angel
Author: La Roche Spotters
Designing an airport runway
One of the key elements of an airport is the runway. In fact, if there is no runway, there is no airport anyway. The runway is the place where airplanes take off or touch down. Then, the runway features will be an important issue to bear in mind.
First of all we have the runway orientation. The runway direction will be a major fact in terms of airport operations. A wind intensity and direction research must be done in order to obtain and gather wind data, and then determine the most likely wind direction in that area. Now let’s talk about physical characteristics.
The two more important sizes are the runway length and the width. Depending on the aircraft expected to operate on that airport, you might use larger or shorter distances. There is no specific runway length established by FAA or ICAO, but could change from 200 meters to infinite (if we could have that region). About the runway width it is mandatory to be greater than 18 meters up to 60 meters (able to land an A380). There are other physical matters, like strips up to 150 meters (around the runway) and shoulders up to 15 meters (paved margins at both sides of the runway).
In addition, to promote the most rapid drainage of the water, there should be a transverse slope not greater than 2%. Longitudinal slopes cannot be greater than 2% (just imagine a 3000 meters runway, 2% would mean 60 meters of vertical variation).
Fly-by-wire and Airbus Laws
Nowadays, commercial airplanes do not fly with metal wires moving the ailerons anymore. Now it is managed digitally, from the source (the sidestick or yoke movements) to the control surfaces movement. This system is called Fly-by-wire.
The fly-by-wire system consists of some computers (5 computers on board the Airbus’ planes, 3 primary and 2 secondary), that read the pilot movements, interpret them, and it sends a modified signal (from the original one) to the control surfaces.
All these means that the airplane movements will not match proportionally what the pilot is doing actually. This philosophy shocked a lot of pilots, they couldn’t imagine flying something without a cable between the yoke and the surfaces. Finally, it was demonstrated that this system was much efficient, safer and much versatile.
Airbus was the first one using fully fly-by-wire (A320 were the first) and they create a set of laws that would govern this system. There are 4 laws: normal law, alternate law, direct law and mechanical back-up depending on the degradation of the airplane.
- Normal Law: It is on when normal operation is carried out. It controls the 3 axis (pitch, roll and yaw) balancing the aircraft and interpreting the sidestick movements. In addition, it offers some envelope flight protections (on pitch attitude and roll attitude) and alleviate load factors, like the gravity when turning for a much better comfort.
- Alternate Law: If a minor failure exists (sensors disagreement, computer blackout, hydraulic system upset,etc) this law becomes the active one. Basically it provides the same control as the normal law, but without protections. Also, the roll control becomes “direct law-like” control.
- Direct Law: If a major failure exists (radio altimeter failure when approaching, 3 inertial references down, etc) this law become the active one. Then, the movements of the control surfaces are the same as the sidestick movements. There is no auto trim, and any protection system will be available (even alpha-floor for stall warning).
- Mechanical Back-up: This mechanical aid should be used when the electrical system is all down. Then, the airplane can only be controlled with the trim wheel for pitching, and rudder pedals for rolling.
The SELCAL Code
The SELCAL system or Selective Calling system, commonly used in aeronautical communications, is a multiple system that allows the radio ground-based operator to send a signal to the aircraft that wants to establish a communication. In other words, when an ATC want to talk with an airplane flying over the ocean, he pushes a button and the airplane’s crew receive a message. That is kind of worthy in oceanic routes, where HF (High Frequency) communications give a lot of background noise, and pilots usually turn off the squelch until they receive this signal.
In order to identify each single aircraft, a SELCAL code is assigned to each one. This code is made by 2 pairs of letters (using from “A” to “S” excluding “I” and “O”) and each letter has an assigned frequency. Then, when the operator wants to talk with that aircraft, a 4-tone signal is sent with those letters. Everybody who is in that frequency will hear that sound, but only the one with that code will receive a sound alert (bling-blong-like sound) and a light alert.
There are 10920 different SELCAL codes. That’s the reason why there are duplicate codes (two airplanes, same code). Only airplanes operating oceanic routes use that system though. So, when a duplicate code exists, they make certain that those airplanes will operate in widely separate parts of the world.
ARINC (Aeronautical Radio Inc.) issues these codes in the US. You can find real-world SELCAL codes in this website just entering the registration number.
5 commentsVirgin America will launch an in-flight WiFi
Virgin America will release an in-flight wireless Internet on all his flights by the second quarter of 2009. In fact, they flew a test flight from San Francisco to test the whole system and it kinda works.
This gadget, called GoGo, will not forbid any special content, but there will be some constraints though ( no Skype, no IP voice systems,…). The company’s philosophy is not to edit the content that passengers want to watch, but to offer WiFi in order to let the people choose what to watch. This system will be available above 1000 feet and it works with 3G technology.
Thence, get connected in the airplane will be $10 on short flights, and $13 on longer legs. You just need a laptop to get access. Virgin says that later in 2009 they will include an integrated in-flight entertainment system, that will give connectivity to people who don’t have laptops or PDA’s.
Of course, nowadays, a lot of airlines are willing to incorporate this devices to their birds.
Source: Original Link
Oshkosh: The General Aviation Mecca
Each year since 1953, a huge aviation event take place in Oshkosh, a little town in Wisconsin (USA). In Wittman Regional Airport is where aviation fans gather each summer to spend one week with their fellows. Is the greatest general aviation ever seen, not only because of the airshow (where more than 2500 show aircrafts participate each year), but also exhibitors, forums, courses and so on.
EAA, The Spirit of Aviation, is the organzation who plan this whole event. They join thousands of people with aviation interests for one week at Oshkosh. Every general aviation pilot from the US (maybe from other countries as well) is willing to reach their vacations and fly to that little but crowded airport.
Apart from homebuilts, antiques, classics, ultralights and rotorcraft, there’s also big birds like boeing 747 Cargo (Dreamlifter), jet fighters and commercial airplanes. Also, they arrange some courses to enroll right there, giving some thoughts about avionics, engines, structures or pilot skills.
If you are eager to join this event, you can do it now at EAA AirVenture Website and you’ll meet them on July 27th 2009.
