Ari

Spiff is an engineer, so please respond to his post above.

I never claimed to be an expert an anything other than common sense; that Mythbusters reference and the "bub" after it is condescending, and that is arrogant.

Please also explain (using your expertise) the distinction between taxi in and taxi out when it comes to signal interference. (Hint: saying "you aren't an expert" doesn't explain anything and is arrogant, so don't answer using that).

magiciansampras

LOL, another armchair aviation expert.

Who said anything about signal interference? There are a variety of reasons why the FAA limits the use of electronic equipment that has nothing to do with signal interference. But to your point directly, you think airplanes are using navigational aides on the ground other than lights, runway markings, etc?

Ari

He's an engineer and that's what we're talking about; don't change the subject.

I see your confustion with my posts and it is due to my use of the term "signal interference" to mean "interference caused by cell phone signals" which is not really what "signal interference" really means. Serves me right for being lazy and not wanting to type a few extra words; this one's my fault.

Now then, please answer the question about taxi out in the context of interference caused by cell phones or other devices allowed during taxi in and why, from an engineering standpoint, that makes sense.

Boggie Dog

Could you list the "variety of reasons" FAA would limit electronic equipment that has nothing to do with signal interference?

Shielding of modern avionics has reduced the chance of outside interference to just about nil and that remaining chance would be limited to strong signal sources.

If privately held transmitting devices were really a safety issue do you really think FAA would allow them in the passenger cabin?

Saying something to a person who has not turned off their gear is one thing, but if they do not respond what is the point of making an issue out of it? If you feel that strongly say something to the crew, it's their problem to deal with not yours.

themicah

Some pretty extreme positions here...

There is no question that GSM devices (particularly Blackberries) cause "Blackberry buzz" on many audio devices. I've been on countless conference calls for work where the buzz was a problem, and have been to a synagogue where the PA system would buzz whenever an incoming call came into a live GSM phone in the sanctuary (they had a big sign begging people to switch their phones completely off, but many would simply put them in vibrate). The WSJ wrote an article about it a couple years ago.

Whether this can actually interfere with airplane navigational or communications equipment, I don't know. But it certainly could in theory.

As for taxi in vs. taxi out, I always assumed that the distinction had nothing to do with differences in the potential for interference but with enforcement. The critical time they need everything to work is the actual takeoff and landing, not the taxi time. On landing, once you're on the ground, the critical time has passed. On takeoff, however, passengers (and even FAs) don't necessarily know when exactly takeoff is going to occur, and the FAs are typically seated and therefore unable to patrol the cabin to make sure everything is off right before the critical time. So it's simply easier to make the rule effective as soon as the cabin door is closed.

This is of course all speculation (I'm an armchair engineer and proud of it!) and given how many times I've seen people e-mailing and texting during taxi out, it's clearly not THAT critical of a rule. But the blanket "obviously the rule has no basis in reality" statements are almost as idiotic as the sheeple who fear the plane will crash if somebody sends an e-mail during taxi time.

magiciansampras

Why does being an engineer have anything to do with this? It's still about being the armchair expert. The "I know better than anyone else" hubris that is being discussed here.


I still don't understand your question. If the FAA's concern is that unknown electrical devices, such as cell phones, may affect navigational equipment, why would there be a navigational concern on the ground? Navigation on the ground is done by looking out of the window, not looking at a computer.

Who knows. Certainly not me. But I do understand the notion of precautionary principles and the disincentive for airlines to do significant tests when there is little (or no) financial return for doing said tests.

N965VJ

That was picked up by our very own gleff on his Boarding Area blog.

Here’s a portion of the original post by a 20-something FA with 4 years experience under her belt:

Oh and we aren't being paid yet so unless you want us to board earlier before each flight leaves, making Your ticket price higher all so we can go over the specific electronic devices to be on and off for each plane, they all have to be off.

We really don't have time to even think during boarding so please just help make life a little easier for us all and turn them all off. This means Anything with a battery and on/off switch. Don't make us ask you two, four or eight times, it really doesn't do well for our mood for the flight.

I’ll let others speculate what kind of FA she’ll be in ten years, if she decides to stay on the job.

A few comments from folks with a little more experience in the field of avionics:

Do you even know the history FAR 91.21?

I am sorry to advise you that there have been no accident or incidents involving any piece of Electronics or EMI ever. Boeing has done test after test with no proof. The rule is in effect basically so the pax are prepared for any incident on take off or landing. Which is not wrong but I just can't stand people providing wrong information. Sorry it's a pet peeve. I do have the experience on this. I have over 30 years in aviation as an Avionics Tech, Aircrew, pilot and flight attendant and accident investigator with both military and civilian experience so I have researched and know that there is no proof! Trust me if your A319 had an avionics problem it was likely just broke not due to some cell phone, ipod or EMI related equipment.

And:

On the background of FAR 91.21:

The rule FAR 91.21 was enacted in 1963. The reason was during a 1961 Washington Redskins football game an airliner was attempting to land at Washington Dulles Airport. Many of the passengers had AM transistor radios and back then they were using ADF navigation to land. One of the main hazards of ADF is electrical effects. Since so many pax were using transistor radios to listen to the Skins game they could not get the ADF indicator to lock onto the station. Hence the new rule.

However, nowadays it makes absolutely no difference and there have been no confirmed incidents or accidents resulting from cellphones. I have about 3,000 hours combined as pilot and aircrew both military and civilian and I often talk on my cell while flying and or check email with no negative effects. Basically during critical time of flight takeoff and landing that is when you want to be aware so the rule is basically in place for safety reasons.

Ari

Many posters complain about people not turning off their phones until just before takeoff, that's why . . .

magiciansampras

As a previous poster said, takeoff times vary. Isn't is just more comprehensive to have the door closed rule when taxiing out?

gatorray

Thank you for the clarification. I subscribe to his Boarding Area blog and I navigated to the FAs blog through his. Credit where credit is due.

Still, I want to know what the gadget is that tells the pilot that I am on a blackberry. Does it capture personal information about me.

clrankin

Pot, meet kettle. The reality is that you don't know more than anyone else on this matter either. And the airlines are pretty much clueless on this too.

As previously stated, it's a nonsense regulation. If phones presented a considerable danger, with the number of flights that occur on a daily basis there would surely be a string of incidents and accidents reported that could be traced back to this. And since planes aren't experiencing aborted take-offs and aren't falling out of the sky in droves, I'll accept anecdotal evidence that phones left on do no harm over no evidence to the contrary.

Boggie Dog

[QUOTE=N965VJ;13950645]

[I][URL="http://boardingarea.com/blogs/viewfromthewing/2010/05/12/please-turn-off-all-electronic-devices/#comments"]On the background of FAR 91.21:


I'm having a bit of trouble with the ADF thing.

ADF in aircraft are receivers (only) that are tuned to any ADF broadcasting station giving a point to the station.

I don't see how having multiple receivers close together would have any bearing on the aircrafts receiver.

magiciansampras

Except I'm not the one breaking the rule. @:-)

clrankin

No, you're just the one who wants to play judge, jury, and executioner on those who ignore an inconvenient, useless rule.

The same arrogance still applies. It's kind of like being the one little kid in grade school who reminds the teacher that she forgot to assign homework on a Friday, or the one who rats out other kids for bringing a cell phone to class...

Spiff

You're in the near field (< 1m) so yes, the possibility becomes a little higher in that area.

It's extremely unlikely that when one is in the airplane cabin that one will be in the near field.

If anyone wishes to carry out a legitimate scientific experiment to answer questions about these devices, I'm happy to serve as PI for a reasonable fee.