Electronics & Planes Don't Mix?

dirtydamo writes "The Sydney Morning Herald is running an interesting story on the old debate on whether electronic devices cause problems on planes. It appears pilots are pretty much accustomed to handling weird problems with equipment, which they attribute to passengers' portable devices. More research is needed to determine whether or not this is the actual problem, but the article certainly makes me a little uneasy about modern air travel."

Comments

Could a HERF weapon be made notebook sized?

[Anonymous Coward]

http://www.amazing1.com/emp.htm

Sad I have to post this anonymously.

Re:This is exactly right.

[duffbeer703]

What airline to you fly?

The last plane I was flying coach the aircraft was a virtual cattle car. Most city busses have more room and are usually more comfortable than the vast majority of aircraft.

Re:Can't they insulate this stuff?

[psyconaut]

See my other reply to someone asking this, it's not the cockput that's the issue...it's the wiring looms that run all over the aircraft that end up acting like RF antennas.

-psy

Re:Too far fetched...

[stilwebm]

If we design our aircraft so poorly as to not have any manual controls, then some re-evaluation needs to occur.

Exactly. The problem however, is when pilots (or air controllers) rely on instruments they believe to be accurate and have no way of knowing whether this is true. In some instrument landing system (ILS) landings, it is virtually impossible to land without the instruments or verify all the parameters. More often, this only makes it hard to recover from another mistake such as leaving air brakes on or verifying that the ground aid is working. Pilots have well defined procedures for preventing these mistakes and for recovering from them as well. Yet the danger of faith in an inaccurate instrument can lead the crew to feel nothing is wrong until it is too late.

Re:Can't they insulate this stuff?

[ddimas]

The problem is not alpha, beta or gamma radiation, the problem is that the wires controlling the airplane make a really nice radio frequency antenna. Those wires by necessity run throughout the plane. The obvious answer is to redesign the passanger compartment to make it a properly grounded faraday cage. The side effect will be that you won't be able to use communications devices. Altrenativly you can rewire the entire plane with grounded control (coaxial) cables, think $$$ and weight = shorter flight range, if you can cram them in there at all.

BTW airplanes are not the only place this kind of interference shows up. Any instrument with an exposed wire is subject to this kind of RF interference. Examples include medical equipment, entertainment devices, and scientific instrumentation.

I have personally identified it in HPLC chromatograms (analytical chemistry) where it shows up as spurious peaks (everybody else was thinking sample contamination). We had to ban communications devices from the labs, the security guards and manufacturing people used to grumble, but oh well.

I'm a pilot

[Teahouse]

I'm a private pilot, and even on small planes we can have this problem. The problem does exist. It's not some pilot conspiracy to stop you from playing your Game Boy. Navigation is performed with the aid of a gyroscope and magnetic compass and VOR stations.(GPS is a few years away from becoming a standard). Any number of electronic devices can affect this system. In-cabin devices can have much more affect on these systems then outside incluences simply because you're basically travelling within an aluminum faraday cage. A microwave signal from a cellphone will bounce around inside the cockpit a lot more than if it is outside.

It is particularly crucial that these devices are off during landings. Landing is by far the most dificult portion of flying. On commercial planes, they are often making their approaches in IFR (Insturment) conditions. It takes very little to make approach devices go haywire. You don't want this happening when the visibility is 500ft and you are trying to touch down 30 tons of aircraft in fog. It hasn't happened yet, but sooner or later some aircraft is going to crash on landing because some schmoe couldn't wait till he got down safely to call and tell folks he is going to be late for his meeting. In 99 out of 100 cases there may be no effect on the plane, but it only takes one crucial event to destroy an aircraft. Try to remember that.

Re:Too far fetched...

[Lumpy]

In some instrument landing system (ILS) landings, it is virtually impossible to land without the instruments or verify all the parameters.

I'm pretty sure that's why they still put windows in front of the aircraft.... Unless it's just for pretty pictures and making the workplace more enjoyable.

Granted this wont work in low visibility. but 6 times out of 10 it's not an issue.

It worked for the first 7/8ths of aviation history... I'm sure it will work for while more.

Re:Too far fetched...

[jbwolfe]

Then this will scare you...
Every Airbus ever made has been fly by wire. There is absolutely no direct connection to the flight control surfaces. The closest it gets is pitch trim can manually deflect the stabilizer through a hydralic actuator- the connection is still wired but seperate. All control inputs are fed to seven computers (2 ELACs, 2 FACs, and 3 SECs) which position the control surfaces. The system has three catagories of control law. Without any electrical power, the aircraft is uncontrollable.
Now to ease your fears...
If there are multiple failures of redundant systems, the controls can move from normal to alternate or direct law. Even with complete loss of generator power, the pilot can operate in direct law (on battery) and land safely. Yes, we train in this law. No, its not easy.

P.S. Lightning stikes are common and most aircraft have some damage taht is deferred until the next heavy maint. visit.

Digital Electronics

[Detritus]

The spellchecker is a digital device. That means it uses lots of digital signals with fast transitions, similar to square waves. Square waves, and digital signals in general, have a large amount of harmonic content. That means that a 10 MHz square wave also contains substantial energy at odd harmonics of the 10 MHz fundamental frequency, such as 30 MHz and 50 MHz.

Consumer electronics devices are designed to be cheap. That means that they will not add shielding or EMI suppression unless someone holds a gun to their head.

A portable digital device can radiate large amounts of interference at many different frequencies. What is even worse, the RF output is not constant. Anything with a microprocessor in it will radiate at varying frequencies and power levels depending on what code the microprocessor is executing. This makes it almost impossible to test for interference to specific frequencies.

The earliest forms of computer music involved putting an AM radio near the computer and executing code snippets that would produce the desired sound (interference) on the radio.

Interference DOES exist..

[hoofie]

This is a PDF file of a study done by the CAA in the UK (equivalent to the FAA) on cellphone interference against instruments. It was done in a laboratory to model in-flight circumstances.

To quote from the report (6.1) :
The tests revealed various adverse effects on the equipment performance from simulated cellphone interference. Although the equipment demonstrated a satisfactory margin above the original certification criteria for interference susceptibility, that margin was not sufficient to protect against potential cellphone interference under worst case conditions.

So until there is concrete evidence one way or the other, erring on the side of caution may be advisable - its also one of the last places where you don't have to listen to some dickhead chatting on the phone in a loud voice.

Re:Not too far fetched..

[LinuxHam]

I'd be more concerned with an attempt to take one out on takeoff than landing

That's what happened in Kenya several months ago. A SAM-7 was fired at a chartered Israeli jet that had taken off a few seconds earlier. The terrorist fired it off too early, and the SAM never picked up on the IR signature you worry about. The pilots felt a bump on the left side of the plane and saw the smoke trail as the rocket flew past the plane. Once they reached Israeli airspace, they were escorted in by Israeli F-15's and landed safely.

I'm surprised you don't seem to remember this event. Its exactly what you describe. Except, of course, the missile failed to destroy the target.. more like bounced off it.

Re:Radio?

[Detritus]

Radios are infamous for local oscillator radiation. When the FM signal comes into the radio, it is mixed with a local oscillator signal to downconvert the desired signal to the first IF, usually 10.7 MHz. The local oscillator's frequency is probably set to the frequency of the station you are listening to, plus or minus 10.7 MHz. It isn't unusual for local oscillator energy to escape back up the antenna lead, or to be radiated directly from the electronic circuits.

Most of the infamous "TV detector" vans in the UK look for local oscillator radiation from TV sets. Not only can they detect that you have a television, the frequency of the local oscillator tells them which channel you are watching. The Nazis and Soviets used similar techniques to locate people who were listening to illegal foreign broadcasts.

If you look at a spectrum allocation chart, guess what is immediately above the FM broadcast band (88-108 MHz)? The aeronautical band (108-136 MHz), used for voice communication and navigation. Now imagine that you are sitting on an aircraft, listening to KRAP 106.3 MHz on your FM radio. The radio set the local oscillator to 117 MHz (106.3 + 10.7) to mix the signal down to 10.7 MHz. The FM radio is now radiating a signal in the middle of the aeronautical band, hopefully not on a frequency that the pilot is currently using. The radiation from the local oscillator may be relatively weak, but you are much closer to the aircraft's radio antenna than the control tower or the navigation beacon. This was the earliest noted form of interference from passenger electronics to aircraft electronics, well before laptops, GBAs and PDAs.

Re:Not too far fetched..

[mr100percent]

The 72 virgins are probably the most overblown thing that people seem to remember about Islam. Forget the doctrines of monotheism, all people want to hear about is the virgins. There's a lot more to Paradise than just sex and physical pleasure, you know.

Ok, the Quran says that those who do go to heaven will be rewarded with blessings that eclipse anything on earth; unlimited food, riches, wishes come true. People will be reunited with their relatives, we will all be made young again, there will be no anger or pain. Those who get to the highest part will also be able to see Allah with their own eyes. Also, the believers who make it into Paradise, male and female, are promised beautiful companions called "Houris."

The Quran describes them in some detail. They are basically creations of God, intelligent yet soulless and created to serve the believer who goes to Paradise. They are described as pure, beautiful, lustrous, virgin, and more perfect than any human on earth. The woman of your dreams. A man in paradise will get numerous female servants for himself, while a woman would get male servants.

In Paradise, you can marry them. Even if you were married on earth, they will be invisible to your spouse. Islam is pretty clear in saying that guiltless sex is a reward in Paradise.

To answer your questions, they are made for the believers, they are intelligent yet have no souls. They are created for the purpose of serving the believer. They dont exactly have free will, they are like the angels in that regard. Of course it's worth being with them, since they aren't droids, they are smart but they just cant disobey God.

And no, dirty terrorists who hurt innocent people are sinning, so it's up to Allah if they'll go to Paradise or not.
More info on "the islamic paradise"