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wardialer
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Using GPS Onboard Aircraft?

Wed Dec 01, 2004 1:45 pm

I just heard a friend of mine that took a plane trip and he was using a GPS onboard. Of course, he told me that no one was looking anyway.

But he told me that his reading on the GPS gave him a Ground Speed of 643mph at 38000 feet on the way from Los Angeles to Miami.

I have this Garmin89 Handheld Aviation GPS and I would like to ask if it will give an accurate reading of speed and altitude the next time I fly somewhere?

Because one time I tried it in my car and gave a message that no reception was available. So how could I solve this problem in an aircraft if that were to happen when I fly like my friend did with his GPS unit??? I dont really know what kind he has though.

[Edited 2004-12-01 05:49:32]
 
OpsGuy
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RE: Using GPS Onboard Aircraft?

Wed Dec 01, 2004 1:50 pm

I assume that it would. A friend of mine brought a GPS that he used for hiking along on a flight in a Cessna 172. We tracked the ground speed and the altitude. It was pretty interesting and a relatively cheap GPS. The Garmin would probably work even better. However, I would caution using a GPS on a commercial flight, with all the security concerns today you may run into some unwanted problems.
Is this the Delta House?
 
320tech
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RE: Using GPS Onboard Aircraft?

Wed Dec 01, 2004 2:02 pm

Another concern might be poor reception inside an airliner. Flying a Cessna 172, I have to keep my GPS on the dash to get continuous reception.

Ground speed of 643 mph is reasonable with a tailwind.

I'd be concerned about security too, there's some pretty paranoid people around.
The primary function of the design engineer is to make things difficult for the manufacturer and impossible for the AME.
 
air2gxs
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RE: Using GPS Onboard Aircraft?

Wed Dec 01, 2004 11:13 pm

I've used GPS many times when soft-seating. You just need a window seat and basically keep the unit right up to the window.

A high-wing Cessna presents a problem that should be solved by putting the GPS on the dash.
 
747NUT
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RE: Using GPS Onboard Aircraft?

Wed Dec 01, 2004 11:32 pm

I have a Garmin III pilot and have got an antenna extension that has a suction pad that allows me to put the antenna on the windscreen and the unit out of the sun, works great in most situations.
If it's not broken, don't fix it !
 
iakobos
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RE: Using GPS Onboard Aircraft?

Thu Dec 02, 2004 12:36 am

There seems to be a misconception here concerning the location of GPS (Navstar) satellites.

The (more than) two dozen Navstars are orbiting the earth, they are not "geostationary" (geosynchronous).

As long as the receiver antenna has a sufficient unobstructed view to pick up signals from 3 of these sats, the job will be done.

At any time, provided you are in open space, one should be "in view" of 6-7-8 sats. They will be at different elevations and azimuths, none being necessarily "sky up".
 
wardialer
Topic Author
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RE: Using GPS Onboard Aircraft?

Thu Dec 02, 2004 6:42 am

So inorder to use my handheld GPS unit or to make it give accurate reading on an airliner, do I just have to just hold it near the window???
 
Newark777
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RE: Using GPS Onboard Aircraft?

Thu Dec 02, 2004 6:50 am

On a recent delta song flight, I brought my Garmin gps unit on board without any problems. I was only able to get a signal by holding it extremely close to the window, though, and it was a weak signal at that, but I was still able to pick up our speed and altitude.

I've heard though that some airlines tend to be more strict on the topic of a gps on board, but I am not sure which ones. The flight attendants on Song certainly didn't seem to care.
Why grab a Heine when you can grab a Busch?
 
vneplus5
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RE: Using GPS Onboard Aircraft?

Thu Dec 02, 2004 8:10 am

My Magellan handheld GPS works really well on airliners. You do have to hold it very close to the window.

The GPS knows what satellites it should be seeing and draws a representation on the screen of where in the sky they should be. Let's say it is looking for 10, it will normally find about 7 with maximum signal strength, and the other 3 will have zero strength, obviously being shielded by the fuselage.

It's very interesting to watch it work out where the satellites should be. It often takes a few minutes to realise it's so high and then it will re-draw the sky diagram correctly.

I haven't had any problems with cabin crew though. Some know exactly what it is and ask me where we are flying over or how fast, etc... Sometimes they think it is a mobile phone, so my advice is to just use it discreetly. Propped up on the plastic 'ledge' of the window against your shoulder normally does the trick for when you want to eat/talk but not let it lose the signal.

Rarely, cabin crew (esp. young ones) will just want to show who's the boss and bark at you. Still nothing to worry about.

Asking for permission outright is pretty silly, in my opinion. The automatic reaction will be 'no'. Best not to say anything unless asked.

If there's a problem, turn it off, no harm done. Better luck on your next flight. There's no sense getting into an argument.


However, I would caution using a GPS on a commercial flight, with all the security concerns today you may run into some unwanted problems.

ugh! This just reeks of paranoia. Queuing up to go to the toilet is a 'security concern' too, I guess? Now where did I put that old barf bag.. I wanna be sick.
 
greg3322
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RE: Using GPS Onboard Aircraft?

Thu Dec 02, 2004 8:20 am

Prior to 9/11, I used my Garmin 12 all the time. My first airline trip with it, UA from LAX to MCO, I asked the captain if it was OK to use in flight. He said he wasn't sure if it would work, but go for it. He even gave me a copy of the flight plan to follow along. Upon arrival, he even asked how well it worked! On the return trip from MCO to LAX, the flight attendant decided that I wasn't allowed to use it at all. I asked her to check with the captain, and she came back 30 seconds later saying no. I then gave her the unit, asked her to show the captain what it was. Again, she came back and said, "it must be FCC class C certified and it doesn't say it is" so put it away. I questioned the captain on the way out and he sure didn't want to discuss it. Oh well...

I used it many times after that with no hassles. However, after 9/11, many airlines specifically prohibit GPS units being used on board - AA, HP, and UA that I know of. I guess the fun times flying are long gone...

Greg
 
airplay
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RE: Using GPS Onboard Aircraft?

Thu Dec 02, 2004 11:46 am

Asking for permission outright is pretty silly, in my opinion. The automatic reaction will be 'no'. Best not to say anything unless asked.

Yes. And proceed to make the choice for all aboard to endanger their lives while you play with your unauthorized toy....
 
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N328KF
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RE: Using GPS Onboard Aircraft?

Thu Dec 02, 2004 1:01 pm

Airplay:

That's just sheer lunacy. The electronic emissions thing is garbage, especially with a receive-only device like a GPS receiver.
“In the age of information, ignorance is a choice.”
-Donny Miller
 
Kerberos
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RE: Using GPS Onboard Aircraft?

Thu Dec 02, 2004 3:12 pm

I had no problem using a Garmin eTrex on a flight from Cuba to YVR, however I was on the "north side" of the aircraft, so the farther north we flew and the more north my window faced, i started to lose signal strength to the point that over eastern Washington I was pretty much unable to get a signal lock. Most of the GPS sats are over the equator, so it seems to work best if you can be on the "south" side of the aircraft. I have a hard time using the GPS on the ground without a clear view to the south.
This is your captain speaking. I’ve turned off the no-smokin’ sign. Hell, if the plane is smokin' why can't you?
 
airplay
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RE: Using GPS Onboard Aircraft?

Thu Dec 02, 2004 9:27 pm

That's just sheer lunacy. The electronic emissions thing is garbage, especially with a receive-only device like a GPS receiver.

N328KF, so what exactly qualifies you to announce that? It is quite obvious you don't know what you are talking about here. There have been several studies done that have formed the standards and regulations.

EMI/RFI is a very real thing. I have witnessed interference with aircraft systems from all sorts of devices including unintentional radiators like hand-held GPS receivers.

If you think GPS receivers are not capable of emitting interference, again it is obvious that you don't understand how electronic devices work.

Of course the operation of a personal electronic device won't make the airplane crash every time, but there is enough evidence that if usage is not controlled, the probability of serious interfernce is high enough to conflict with the standards of safety.

It is quite irresponsible to spread incorrect uninformed information regarding operational standards of aircraft. There are other people on board besides you. Don't treat airplanes like high school science projects.
 
david b.
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RE: Using GPS Onboard Aircraft?

Thu Dec 02, 2004 11:51 pm

N328KF, all electronic devices emit radiation. It doesn't matter if it is passive (GPS, CD player) or active (cell phone). Even your car radio and TV emit radiation which can cause interference with other devices. Also, those emissions can be used to locate you using the right devices.
Teenage-know-it-alls should be shot on sight
 
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N328KF
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RE: Using GPS Onboard Aircraft?

Sat Dec 04, 2004 12:37 am

I am well aware of the effects of EMI/RFI. I just believe that it's excessive paranoia by the industry.
“In the age of information, ignorance is a choice.”
-Donny Miller
 
airplay
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RE: Using GPS Onboard Aircraft?

Sat Dec 04, 2004 5:15 am

The electronic emissions thing is garbage...

Flip.

I am well aware of the effects of EMI/RFI

Flop.
 
iakobos
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RE: Using GPS Onboard Aircraft?

Sat Dec 04, 2004 7:26 am

Airplay,

Why the oversensitiveness concerning GPS receivers ?

I do know a thing or two about EMI/RFI, I passed enough equipment through ETSI testing, and I know what to expect from a local oscillator inside a metallized plastic box, that's why I don't see the case.

What kind of interference did you witness exactly inside an airplane from a "receiving only" device ?
 
airplay
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RE: Using GPS Onboard Aircraft?

Sat Dec 04, 2004 7:57 am

Iakobos, how long of a list do you want? I am involved in aircraft design and certification and avionics is my specialty. I have conducted hundreds of EMC tests on numerous aircraft types and various aircraft systems.

I have witnessed interference from many sources including portable electronics devices typically operated by passengers. These devices however are the worst. One factor is the less demanding standards these devices are designed under, however, an even more serious factor is how they are maintained.

Commercial electronic devices employ various active circuits that operate at frequencies throughout the spectrum. When you consider processor speed, board speed, I/O speeds, video speeds etc, the average lap top computer uses frequencies in the ranges of every piece of equipment on modern airliners. What keeps the device from interfering with other electronics in relatively close proximity are various metal shields and electronic filters.

When electronic devices are maintained, there is no guarantee that the shields are replaced or if the device operates to any standard. Portable GPS receivers obviously do not have the potential interference signatures of the average laptop, but they still have the potential to cause interference.

When you consider that a thrust reverser can be deployed by a command on a data bus that happens to be passing through the passenger cabin and that all it takes is a bad shield to cause it to deploy at an inappropriate time, don’t you think this is a serious matter? Don’t you agree that it is quite inappropriate and hazardous for someone to ignore the rules and advocate the use of such devices based on ignorance?

I do.


 
bahadir
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RE: Using GPS Onboard Aircraft?

Sat Dec 04, 2004 10:19 am

I used it on my Skywest flight from SEA to PDX. Made sure to ask the F/A to check with captain. Captain's response was "Let me know if I get lost"  Smile
I even ended up having the gorgeous F/A sit next to me and listen to my geeky explanations  Smile
Earthbound misfit I
 
iakobos
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RE: Using GPS Onboard Aircraft?

Sat Dec 04, 2004 10:37 am

So, I take it you have never witnessed any actual interference.
Me neither, nor anyone else I know in the branch in the last 31 years.

We know that the shielding and/or tuning of consumer products is often inappropriate (though supposedly complying with moderately strict standards), though the amount of unwanted radiation is grossly insufficient to interfere with anything, not even with another consumer product in close proximity.

When you look at the amount of radiation rightly emitted by aircraft communications devices, radar, radio altimeter, transponder, satellite, IFE, video player, etc...it seems to me very awkward to raise the subject of a few unwanted nanovolt (at 1 meter in free space !) from "toys".

With the amount of electronics on board, I am confident that the level of white noise due to the aircraft's electrics and electronics onboard is several order of magnitude higher than any bad toy could generate.


 
airplay
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RE: Using GPS Onboard Aircraft?

Sat Dec 04, 2004 12:21 pm

So, I take it you have never witnessed any actual interference.
Me neither, nor anyone else I know in the branch in the last 31 years.


Um...I assume you know how to read Iakobos, because you can write. How can you come to this conclusion after reading my post?

I have witnessed actual interference numerous times from devices such as cell phones, laptops, portable GPSs, portable DVD players etc.

What "branch" exactly do you have experience in? It is obviously not direct on-aircraft EMC testing.

though the amount of unwanted radiation is grossly insufficient to interfere with anything, not even with another consumer product in close proximity.

Not only is this statement not true, but it truely illustrates your lack of experience in this matter.

Its a good thing you don't control certification of aircraft systems. Your attitude is quite dangerous and irresponsible.

If you get a chance, get a copy of RTCA DO-199. It contains a study of "Potential Interference to Aircraft Electronic Equipment from Devices Carried Aboard". This report helped form the current operational policies regarding PEDs. Educate yourself about the potential of interference then come back and comment.
 
erj-145mech
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RE: Using GPS Onboard Aircraft?

Sat Dec 04, 2004 3:55 pm

Airliners don't fly at 38,000 feet. 37000-yes, 39000-yes, 36000-no. This will change on Jan 5th when domestic RVSM goes into effect, but not now, or up to now.
 
iakobos
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RE: Using GPS Onboard Aircraft?

Sat Dec 04, 2004 9:41 pm

Airplay,

I agree that there is a need for some to raise the specter of interference and keep things in check.

This said, if there was REALLY an evident risk of interference from carried on gadgets, I bet my right hand that all regulation authorities would strictly ban not only the usage but also the presence of any "potentially" hazardous electronic device on board any aircraft, and concurrently there is no doubt that all airlines would enforce it at once.

Not only did nothing like that happen, but on the contrary passengers are expected to use their computers and generate income through the satellites (so-called) broadband links, CD players and the like can be used, and sooner than later cellular telephony spots will be installed onboard and consequently dozens of cellphones will be used simultaneously.

Not much water for your mill, isn't it ?

By the way, you did not mention any case of practical interference you might have witnessed.

..and yes I can read

Iakobos EE
former (and long time) member of the European Technical Standards Institute



 
airplay
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RE: Using GPS Onboard Aircraft?

Sun Dec 05, 2004 12:10 am

Iakobos, perhaps you don’t have access to the airworthiness standards. Here is the FAA version. All other airworthiness authorities have similar standards:

Sec. 121.306

[Portable electronic devices.]

[(a) Except as provided in paragraph (b) of this section, no person may operate, nor may any operator or pilot in command of an aircraft allow the operation of, any portable electronic device on any U.S.-registered civil aircraft operating under this part.
(b) Paragraph (a) of this section does not apply to--
(1) Portable voice recorders;
(2) Hearing aids;
(3) Heart pacemakers;
(4) Electric shavers; or
(5) Any other portable electronic device that the part 119 certificate holder has determined will not cause interference with the navigation or communication system of the aircraft on which it is to be used.
(c) The determination required by paragraph (b)(5) of this section shall be made by that part 119 certificate holder operating the particular device to be used.]


Here is some more reading material for you:

http://www.boeing.com/commercial/aeromagazine/aero_10/interfere.html
http://www.caa.co.uk/docs/50/Gsm_intf.pdf
http://www.tc.gc.ca/CivilAviation/commerce/circulars/AC0106r.htm
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/72F58116704FC3D986256A71006ED5B0?OpenDocument&Highlight=portable%20electronic%20devices

The fact that you are a former member of ETSI makes your comments even more inappropriate and unfortunate. You should know better…..
 
iakobos
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RE: Using GPS Onboard Aircraft?

Sun Dec 05, 2004 1:15 am

Airplay,

Unreconciliable positions. Keep your scythe.
 
bahadir
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RE: Using GPS Onboard Aircraft?

Sun Dec 05, 2004 1:21 am

ERj-145mech wrote:
Airliners don't fly at 38,000 feet. 37000-yes, 39000-yes, 36000-no. This will change on Jan 5th when domestic RVSM goes into effect, but not now, or up to now.

what are you a republican?  Smile There are airliners outside of united States too. RVSM have been in effect in Europe for last 2 years. Over the Atlantic crossing 38,000 is a valid one as well..

Earthbound misfit I
 
david b.
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RE: Using GPS Onboard Aircraft?

Sun Dec 05, 2004 1:22 am

Iakobos, your ignorance is bliss. Hope you don't work in aviation or fly on my plane.
Teenage-know-it-alls should be shot on sight
 
iakobos
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RE: Using GPS Onboard Aircraft?

Sun Dec 05, 2004 3:30 am

Thanks tenderfoot,

I guess you never used a handheld VHF or a GPS or a laptop in your plane and you don't fly on airlines which do not apply the rules as per para 1 to 4 (i.e. none thus).

Did you notice that section 121.306 para 5 leaves the door totally open for "self regulation" by the certificate holders (the airlines) ? it says enough.

Even in static conditions, it is hardly possible to willingly create an interference susceptible to have an influence on a/c electronics, or did you witness something for real Airplay ?

If I were to follow you, all world airways would avoid passing close to any major source of radiation (megaWatt class). Do they ?


 
airplay
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RE: Using GPS Onboard Aircraft?

Sun Dec 05, 2004 6:26 am

Did you notice that section 121.306 para 5 leaves the door totally open for "self regulation" by the certificate holders (the airlines) ? it says enough.

Iakobos, the regulation sets the stage. The guidance material that I provided links to provide the guidance for the airlines to follow to meet the standards. The dorr is NOT wide open.

Even in static conditions, it is hardly possible to willingly create an interference susceptible to have an influence on a/c electronics, or did you witness something for real Airplay ?

I don't know how many times I need to repeat myself. I won't even bother addressing this obviously uninformed question.

If I were to follow you, all world airways would avoid passing close to any major source of radiation (megaWatt class). Do they ?

Strange you should mention that. Ever heard of HIRF? Probably not...and thats because you don't know what you are talking about.

When the first glass cockpits and digital interfaces were introduced, some operators experienced total failures of the displays. Others experienced odd behavior of aircraft systems such as erratic navigation or AFCS operation.

The occurrences of such behavior was soon linked to the operation of the aircraft near High Intensity Radiated Fields (HIRF) from high power transmitters. Since that revelation, new aircraft systems have been subject to additional susceptibility testing and new design methods have been introduced to reduce the probability of such interference.

HIRF hardened designs don’t always guarantee that interference will not happen. Again it also depends on the consistent good maintenance of the systems and avoiding stray emissions.

In one well known incident, a Bell 407 was flying along when the pilot experienced a serious reduction in power while he was talking to ATC. He declared an emergency several times but then found the engine running normally again. He soon discovered that his radio transmissions were causing the engine to reduce power. He landed normally and inspection found that the collar that held the cable shield around the FADEC harness connector was broken and a short length of cable was exposed.

Here is some more light reading for you Iakobos. Please…take my advice and educate yourself before you spread more incorrect information.

http://www.assassinationscience.com/HERFData3.pdf




[Edited 2004-12-04 22:29:07]
 
iakobos
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RE: Using GPS Onboard Aircraft?

Sun Dec 05, 2004 8:15 am

You can steam as much as you want and use whatever names you wish to gratify me Airplay, you did not come up with one single case of real interference on aircraft systems due to personal electronic devices (that you witnessed), and thousands of a/c are flying every single day with such devices onboard, despite the cautious standards and in full knowledge of the civil aviation bodies, the a/c manufacturers, the airlines, the pilots and the insurances.

Reading is theory, I suggest you connect a long whip to your spectrum analyzer's RF IN, place a GPS receiver at a distance of 1m and tell me what you find and where in the frequency spectrum. Sure you have these at hand.

Where in your idea is the line between non harmful and potentially harmful electrical field ?










 
airplay
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RE: Using GPS Onboard Aircraft?

Sun Dec 05, 2004 8:41 am

You can steam as much as you want and use whatever names you wish to gratify me Airplay, you did not come up with one single case of real interference on aircraft systems due to personal electronic devices (that you witnessed)

Iakobos, I made the following statement very early in this dicussion and repeated it later:

Iakobos, how long of a list do you want? I am involved in aircraft design and certification and avionics is my specialty. I have conducted hundreds of EMC tests on numerous aircraft types and various aircraft systems.

I have witnessed interference from many sources including portable electronics devices typically operated by passengers.


These observations were made during certification testing and documented in that context.

You chose to ignore my statements and continue to accuse me of not "coming up" with any single case. Your powers of comprehension of the written word are astounding.

Of course if I published documentation out of our records, you would just denounce it because it doesn't show up in any public record. But neither does any other certification documentation. So I included a link to Boeing who has documented such interference, but you chose to ignore even that.

There's not much more to discuss except for the erosion of your credibility due to your posts. You would be wise to quit before you do more damage.

 
iakobos
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RE: Using GPS Onboard Aircraft?

Mon Dec 06, 2004 6:05 am

Well well, out of public records

From Transport Canada:
Devices that may be used include, but are not limited to:
1 audio or video recorders;
2 audio or video playback devices;
3 electronic entertainment devices;
4 computers and peripheral devices;
5 calculators;
6 FM receivers;
7 TV receivers; and
8 electric shavers.


From Boeing
Though many cases of EMI have been reported over the years, with PEDs suspected as the cause, it has proven almost impossible to duplicate these events. "almost impossible" actually translates into "we never could".
If they only even once could have found an actual interference, the sentence would have been very different.

(re B737 '95) Boeing participated with the operator on two flight tests with the actual (suspected) PED, using the same airplane and flight conditions, in an attempt to duplicate the problem. Using even these extensive measures to re-create the reported event, Boeing was unable to confirm the reported interference between the PED and the airplane system.

(re B767 '96) Boeing purchased two of the actual suspect units through the airline and tested them in the laboratory, along with three off-the-shelf units. It was determined that these suspect units had emission profiles similar to the off-the-shelf units and that the levels from these devices were below airplane equipment emission limits.

(re B747 '98) In the Boeing navigation laboratory the (suspected) unit was placed next to the FMCs, control display unit, and integrated display unit, but the reported anomaly could not be duplicated.
As a result of these and other investigations, Boeing has not been able to find a definite correlation between PEDs and the associated reported airplane anomalies.

The RTCA concluded that the probability of a PED interfering with an airplane receiver system is very low. In the case of an ILS localizer antenna, the probability of PED interference was calculated as one in one million.

Operation of non-intentional transmitters should be allowed for use during noncritical stages of flight unless the operator of the airplane has determined otherwise.

And in all instances, the usage of PED (non-intentionally transmitting and intentionally transmitting) remains the responsibility of the a/c operator (and the PIC). In other words, the regulators do not prohibit PED's and their usage.
IF there really was a danger, do you think this would be the case ?


I did my best but I could not find a trace of proven interference, nor does Boeing.

I remind you that the post is about non-intentionally transmitting PED's, in other words everything that is not intended to actually transmit.
 
airplay
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RE: Using GPS Onboard Aircraft?

Mon Dec 06, 2004 10:16 am

Iakobos, I thought you would heed my caution...but here we are again.

The RTCA concluded that the probability of a PED interfering with an airplane receiver system is very low. In the case of an ILS localizer antenna, the probability of PED interference was calculated as one in one million.

The FAA (and other airworthiness adminstrators) provide guidance for determining acceptable probability of hazards. The applicable reference document is FAA AC 25.1309-1A.

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/50BFE03B65AF9EA3862569D100733174?OpenDocument

They classify hazards as minor, major or catastrophic.

The FAA defines a catastrophic failure as one which would prevent continued
safe flight and landing. The acceptable probability of such a failure is 1x10-9 occurances per flight hour which equates to 1 failure per billion flight hours.

Based on just the Boeing information, the operation of PEDs don't meet the standard if a catastrophic failure was identified. The numbers must be adjusted for every other PED operating in the airplane. Just adding 1 other will double the probability of a hazard. Also note that Boeing is calling on operators to be more vigilant in reporting anomilous behavior of aircraft systems when PED interference is suspected.

If you read the Boeing information closely you would read that they did in fact correlate misleading information in the cockpit to the operation of a PED. Arguably they did not observe a "catastrophic" failure but hazardously misleading navigaton information is classified as a major failure who's accepted probabilty is 1x10-6 or 1 occurance every million flight hours. Having 2 PEDs operating on board exceeds this safety margin.

I can go even deeper into the subject, but the fact is, the threat of PEDs interfering with aircraft systems is real. Thats why the operation of these devices is regulated. Thats why the design standards for aircraft include a great deal of EMI/RFI references. Thats why HIRF and EMC are huge buzz words in the industry. And even with all the vigilance, there are still reports of odd behaviour of systems attributed to PEDs.

I did my best but I could not find a trace of proven interference, nor does Boeing.

That's like saying you can't find information on how many times Bell failed when inventing the transistor. It is proprietary information that is not generally released. Tell you what though. Keep telling people its OK to operate PEDs in aircraft without informing the flight crew. Sooner or later you'll have an accident to read about....

Any other airworthiness standards you want to dismiss as rubbish?
 
videns
Posts: 132
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RE: Using GPS Onboard Aircraft?

Mon Dec 06, 2004 1:30 pm

On one hand I'm all for Iakobos' statement, and think that Airplay's attitude is a little too tight, BUT...
I agree with someone else in another (similar) topic in this forum (I don't recall who it was), but he/she said that when it comes down to interference, it's all based on a "what if" situation, which agrees a little more with Airplay's statements....
I'm involved in electronics, and although I rarely have anything to do with life safety, I sometimes see things where the first thing in my mind is "What the f...!!!". That being said, on aircraft systems, it only takes a sloppy job to create a serious accident...
But then again, the probabilities are really small, but they're there....
Travel? Why would i travel if I can watch it on TV?
 
iakobos
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RE: Using GPS Onboard Aircraft?

Tue Dec 07, 2004 1:54 am

Also note that Boeing is calling on operators to be more vigilant in reporting anomilous behavior of aircraft systems when PED interference is suspected
This is a strange interpretation, when I read the text on Boeing's site, it is clearly advising operators to come up with detailed reports instead of the numerous and vague reports suspecting PED's interference throughout the years, and which have never led to any sort of evidence.

...but the fact is, the threat of PEDs interfering with aircraft systems is real. Thats why the operation of these devices is regulated.
Wrong, the ACTUAL fact is that the usage of PED's onboard a/c is left to the responsibility of the operators, and most if not all do allow it, except during the critical phases of flight (i.e. t/o, approach phase and landing), and even this is not strictly enforced.

I do not have to tell people to do it, they are doing this since the advent of portable computers, quite a few years back. Personally I follow the PIC's instructions at all times, even if they would look inappropriate in my view.

...proprietary information that is generally not released
You want me to bite on this ? you imply that cases of interferences from PED's have actually been found and that still, there is no ban on the usage ?
In other words, an aircraft manufacturer would in full conscience know that there is a real danger and still would let its planes fly with the potential culprit on board ? this would be criminal Airplay.

Having been a member of a standards institute, you should realize that I am not a partisan of the "rules are made to be bent" philosophy, but exactly the contrary.
However, I can find no motivation in trying to be more catholic than the Pope.

I guess you totally object to the coming "flying cellular cell" (ARINC and others) that will not only allow pax to use (their own) cellphones onboard but furthermore incite them to use it.
We are not talking weak unintentional spurious emissions here, we are talking moderately powerful intentional emissions from dozens, if not hundreds of sources simultaneously.

 
airplay
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RE: Using GPS Onboard Aircraft?

Tue Dec 07, 2004 2:32 am

Iakobos, as discussions age, especially discussions where there are two quite different views, they become so detailed and convoluted as to miss the original point of the whole issue.

You want me to bite on this ? you imply that cases of interferences from PED's have actually been found and that still, there is no ban on the usage ?
In other words, an aircraft manufacturer would in full conscience know that there is a real danger and still would let its planes fly with the potential culprit on board ? this would be criminal Airplay.


Yes. They have actually been found. And the aircraft manufacturers do not have power to enforce legislation regulating the use of devices that have the potential to interfere with aircraft systems. The operators do, and therefore are charged with regulating their use. What IS criminal is when passengers operate PEDs without the permission of the flight crew and you may remember THAT is the issue I am addressing right from my first post.

You will find no reference to PEDs in FAR 25 because they are not an aircraft manufacturer’s issue. They are an operational issue. However, you will find several standards who’s purpose is to provide as much resistance to such interference from all sources as possible. Why would there be such standards if the problem didn’t exist? Of course several events must transpire before interference is the result. One event could be improper maintenance of shields.

Of course, the probability of a problem arising is very low and the appropriate measure of caution is taken as is with ANY hazard identified in aircraft. The use of PEDs are not banned. They are restricted to use during non-critical phases of flight, while the flight crew is aware of their use and intentional radiators are not allowed. And even though you consider the regulation open to interpretation, you fail to consider the guidance material.

Airlines who follow the guidance and therefore meet the regulation don’t allow use of PEDs during critical phases or flight or without permission of the flight crew.

You can go on and repeat ad nausum that the chances are remote. Yes. Everyone in aircraft certification will agree with you. Does that mean they should not be addressed? NO. Does that mean that they are not capable of causing a hazard? NO. Does that mean that its OK to covertly use your PED on an airplane? NO!

Why not just take a hammer to the window during your flight? They are designed to take such blows aren’t they? The chances that the window will break is slim right?
 
airplay
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RE: Using GPS Onboard Aircraft?

Tue Dec 07, 2004 2:48 am

I guess you totally object to the coming "flying cellular cell" (ARINC and others) that will not only allow pax to use (their own) cellphones onboard but furthermore incite them to use it.

AirCell’s system that would allow you to use your cellphone is quite controversial and I doubt you’ll be seeing it any time soon. Especially on airliners.

They need waivers on a couple of federal laws and the risks are too high in my opinion for them to receive any.

The system is supposed to limit the emissions from your cell phone by preventing it from ramping up power in a search mode. It doesn’t however consider failures.

Do you really want hundreds of cell phones sitting in an airplane turned on when the AirCell box fails? Does the FCC? I doubt it. Can you imagine if such an airplane passed over a large city tripping every cell tower for 300 miles with multiple channels?

I am well aware of the issues regarding T-PEDS. The RTCA has recently developed guidance for such systems and the FAA has issued a memo calling for issue papers for anyone involved in installing such systems as wireless LAN in aircraft.

So..yes. You will start to see a proliferation of transmitting PEDs in aircraft. But not without a great deal of scrutiny, careful design and regulation. Cell Phones? In flying airplanes? Don’t hold your breath.
 
lapa_saab340
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RE: Using GPS Onboard Aircraft?

Tue Dec 07, 2004 3:42 am

Regardless of a particular airlines' policies regarding the use of PED, they are routinely used even on 'critical' phases of the flight where their use is supposedly not allowed...

I've followed your posts Airplay, and while I have no expertise in this area, I share Iakobos' logic on this. If PEDs do really pose a potential threat to safety, they should be banned from aircraft altogether. Saying 'turn it off' to passengers is not good enough, for as long as they are present in the cabin there will always be the potential of somebody using them at the wrong time. And I see it countless times, people keeping their CD player on, video camera, GPS unit, you name it, after the announcement to turn off all PEDs is made.

And it happens every day, so one wonders just how many cases of interference from these devices affecting a/c systems do occur in airline ops, if any?

 
airplay
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RE: Using GPS Onboard Aircraft?

Tue Dec 07, 2004 4:04 am

I've followed your posts Airplay, and while I have no expertise in this area, I share Iakobos' logic on this.

That's the key to this entire discussion....we have many who have "no expertise" passing judgment on which regulations to ignore.
 
erj-145mech
Posts: 305
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RE: Using GPS Onboard Aircraft?

Tue Dec 07, 2004 4:23 am

Username: Bahadir
From United States, joined Oct 2001, 254 posts, RR: 6
"Reply: 26
Posted Sat Dec 4 2004 17:21:28 UTC+1 and read 203 times:
ERj-145mech wrote:
Airliners don't fly at 38,000 feet. 37000-yes, 39000-yes, 36000-no. This will change on Jan 5th when domestic RVSM goes into effect, but not now, or up to now.

what are you a republican? There are airliners outside of united States too. RVSM have been in effect in Europe for last 2 years. Over the Atlantic crossing 38,000 is a valid one as well.. "

If you had read the first post, the writer said that he was going from LAX to MIA, that would put him in the United States, at least the REPUBLICAN part of the country.


 
lapa_saab340
Posts: 398
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RE: Using GPS Onboard Aircraft?

Tue Dec 07, 2004 5:32 am

Airplay,
That's my point, I'm not commenting on the technical aspects since I don't have the background. But what I'm pointing out is, if emission from PED indeed have the potential to compromise a/c safety, why are these devices even allowed in the cabin? You certainly can't rely on the passengers complying with regulations. So what's the deal? Are the airlines negligent, or is there not evidence regarding the effect of PEDs, or is the interference harmless?

I've personally inadvertently left a PED on during critical phases of the flight before. If this is indeed such an important safety issue, then the enforcement of the rules in place is woefully inadequate. I personally have a hard time believing a passenger playing with his PED 'toys' could easily cause a potential safety hazard.

Airplay, since you mentioned you've witnessed the results of interference from such devices during tests, what steps are taken by the manufacturer regarding this? Are you going to forbid them carrying such items in the cabin, are the effects negligible, is there not enough data to conclude anything, or what?
 
airplay
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RE: Using GPS Onboard Aircraft?

Tue Dec 07, 2004 7:53 am

Airplay, since you mentioned you've witnessed the results of interference from such devices during tests, what steps are taken by the manufacturer regarding this? Are you going to forbid them carrying such items in the cabin, are the effects negligible, is there not enough data to conclude anything, or what?

Um…haven’t you been reading? Based on testing and analysis, the regulators have introduced rigid design standards to reduce the probability of interference. These standards prohibit the use of devices that intentionally transmit radio frequencies and limit the use of other electronic devices to non-critical stages of flight and only following permission from flight crew. There are exceptions that are allowed as outlined by the standards and guidance material. Remember, the standards are only as good as the condition of the systems involved. A maintenance mistake on the airplane or even a PED can defeat the design properties that are meant to resist interference.

The bottom line is that with these measures in place, the risk is small as long as the majority of passengers heed the regulations. Having said that, it is irresponsible to advocate breaking the rules and declare the interference doesn’t exist. It exists, there are adequate procedures in place and the regulations should be respected.

If you consider the risk small enough that the regulations can be ignored, then it is obvious you don’t know anything about aircraft certification. Aircraft design standards require the establishment of the probability and classification of failures. The analysis deals with miniscule numbers. When you consider the amount of flight hours tallied each day on the global fleet of aircraft, and the amount of accidents every day, a tiny change in safety margins can result rather large increases in the accident rate.

Follow the rules and the end product is a safe airplane. Ignore the rules, and you chip away at the safety margin and provide a link in the famous chain of events that cause airplane accidents.
 
iakobos
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RE: Using GPS Onboard Aircraft?

Tue Dec 07, 2004 8:19 am

Airplay,

You are evidently missing some points I mentioned since you keep hammering on the same nail.

I am for (regularly updated) regulations, and their strict application, even if it annoys passengers and their constant quest for comfort and entertainment. Loud and clear ?

Eventhough I am a radio-man by hobby and by profession, I am going as far as considering totally improper the usage of cellphones by pilots themselves, eventhough I know that the risk is extremely close to 0 and that they take full (ir)responsibility.

And yes, I also worked in the airline industry and I flew my share in cockpits, so I know how much cellphones (even personal sat-phones) are common on the flight deck, I even had a pilot friend who remotely and conveniently triggered his house central heating with a 5W VHF handheld while on approach.

But I do not concur with a devil's advocate brandishing the skull and bones about something which nobody else sees as a real danger.
(the post is about GPS receivers onboard an airliner !)

I know that the aircraft manufacturer does not make the regulations, but do not tell me that if a company like Boeing had determined that (non-intentionally radiating) PED's were a safety threat, the regulator would have taken it immediately into account, the manufacturer would have warned the operators about it, the operators would ban the usage and would enforce strict measures to avoid them being used.

I think we will see Aircells soon, and I consider this as a positive move in terms of safety. Why ?? Because it will reduce the inadvertent use of phones (i.e. inadvertently switched ON).
Passengers will be aware that they will be allowed to use their phones when authorized (eg. we might see "cellphone" signs lighting up when the "seatbelts" signs go off), it is likely that pax will check their phone status when the appropriate announcement will be made over the PA, and that the cabin crew will be more attentive to enforce the rules.

Picocells will only be active during cruise (thus at altitude) and cellphones will transmit with minimal power level (100mW). I do not know if it will be implemented, but in case of failure of the onboard cell base station it is technically very simple to prevent the cellphones going in search mode at full power.

BTW, it is impossible to "trip" cellular base stations at 300 miles, even statute.
At altitude it is even not possible to trip the nearest cell bases, due to their highly directional antenna systems (in elevation).



 
airplay
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RE: Using GPS Onboard Aircraft?

Tue Dec 07, 2004 8:47 am

But I do not concur with a devil's advocate brandishing the skull and bones about something which nobody else sees as a real danger.
(the post is about GPS receivers onboard an airliner !)


The post is also about PEDs. A handheld GPS fits the definition. Are all handheld GPS units the same? Let's remember any useful GPS receiver has a user interface attached. And all GPS receivers have active components that have the potential to emit RF. Albeit small potential.

Some have full color backlit displays that are powered by very noisy fluorescent tubes. Others have interface capabilities. I know of a couple that have built-in VHF transceivers. Some people use their lap-top computer as the interface. Even though peripherals are banned by some airlines.

I know that the aircraft manufacturer does not make the regulations, but do not tell me that if a company like Boeing had determined that (non-intentionally radiating) PED's were a safety threat, the regulator would have taken it immediately into account, the manufacturer would have warned the operators about it, the operators would ban the usage and would enforce strict measures to avoid them being used.

They are a safety threat and Boeing (and other manufacturers) have taken the proper steps to mitigate the threat. So have the regulators.

Let's go back to my window example. We all know that aircraft windows are very strong and can withstand a great amount of force. We don't however advise passengers to hit them with hammers they may bring on board. Even though the probability of damage or hazard is small, it is still possible and the results may be catastrophic.

The window example is obvious to most, but the emmisions from PEDs is not so obvious so every armchair engineer out there decides they will ignore the regulations. Does that mean airplanes are falling out of the sky? No. But it may mean a decrease in the safety margin and that people may some day be killed because some guys decides to operate his GPS receiver during a critical phase of flight. Is that worth it to you?

I concede my cell phone examples were a bit off. The cell towers won't be tripped until the aircraft descends. In the mean time they will search for stations at maximum power. The issue of picocells was discussed at a TC workshop I attended last week. As I said...don't hold your breath.
 
SATL382G
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RE: Using GPS Onboard Aircraft?

Tue Dec 07, 2004 8:57 am

Some have full color backlit displays that are powered by very noisy fluorescent tubes. Others have interface capabilities. I know of a couple that have built-in VHF transceivers. Some people use their lap-top computer as the interface. Even though peripherals are banned by some airlines.

FYI: Don't forget there are now bluetooth laptops and GPS devices.....
"There’s nothing quite as exhilarating as being shot at and missed" --Winston Churchill
 
iakobos
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RE: Using GPS Onboard Aircraft?

Tue Dec 07, 2004 10:44 pm

Iakobos: With the amount of electronics on board, I am confident that the level of white noise due to the aircraft's electrics and electronics onboard is several order of magnitude higher than any bad toy could generate

Airplay, we all (or almost) know that it takes only a tiny electric current flowing through a conductor to create a magnetic field, thereby, even the uninformed realizes that any electric powered device radiates unwanted energy.

My main point is that an airplane (systems) in itself is THE major source of radiations, both wanted and unwanted.
Pointing at a GPS display while there are dozens (if not a few hundreds) of fluorescent lamps lighting the cabin is like saying that the weight of the truckdriver's hamburger compromises the safety of the truck.

Since you are the expert here, perhaps you can tell: is there any record of comparative measurements made on a plane in ALL SYSTEMS AND DEVICES OFF and ALL SYSTEMS AND DEVICES ON AND TRANSMITTING situations ?
it would be interesting to know what is actually the level of self-inflicted "interference" (EMI and RFI), and thereon better grasp and relativate the threat posed by non-intentionally radiating PED's.
Anything like that exists ?
 
airplay
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RE: Using GPS Onboard Aircraft?

Wed Dec 08, 2004 3:07 am

Iakobos, I think I've provided quite enough information short of publishing proprietary documents. I have tons of exactly that sort of data. We conduct EMC testing that essentially tests EACH victim agains EACH source. The matricies are huge and it takes a great deal of time to process.

A recent EMC survey I participated in lasted 3 days....and that was just for the galley equipment and inflight entertainment.

Anyway to further feed your appetite for controversy, I offer the following excerpt I scanned for you from the AIP Canada

http://members.shaw.ca/airplay1/Document.pdf

If handheld electronic calculators can interfere with aircraft navigation don't you think a GPS can?


[Edited 2004-12-07 19:12:01]

[Edited 2004-12-07 19:12:27]
 
airplay
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RE: Using GPS Onboard Aircraft?

Wed Dec 08, 2004 4:16 am

Pointing at a GPS display while there are dozens (if not a few hundreds) of fluorescent lamps lighting the cabin is like saying that the weight of the truckdriver's hamburger compromises the safety of the truck.

This reminds me of an incident from a few years ago. The airline I worked for took delivery of a brand new airplane. On the second revenue flight they had a lavatory smoke warning. Upon investigation, there was no fire, but they prohibited use of the lav for the remainder of the flight.

Maintenance was unable to find any problems but changed the detector to avoid the embarrassment of the possibility of prohibiting lav use in future flights.

The lav warnings continued. After several hours of troubleshooting, it was found that the wiring for the fluorescent lamps in the lav was run close to the wiring for the smoke detector. The smoke detector, an optical type, used a sample rate of 120 hertz dithered slightly to avoid syncing with onboard systems. Unfortunately, the ballast supplying the lighting provided AC at 60Hz.

We were able to stop the interaction by affixing a large ferrite clamp around the bundle near the smoke detector.

The manufacturer of the smoke detector was consulted and changes were made to the design.

The reason, Iakobos, I made the comment that fluorescent lamps were noisy, is that they are quite troublesome in aircraft. When a ballast malfunctions, it sometimes results in interference. Furthermore, off the shelf ballasts often can’t be used. They must be designed to reduce the possibility of emissions.

The difference between the fluorescent lamps installed in the airplane and the ones in your GPS display, is the scrutiny they are put under. As my story illustrates, occasionally even the aircraft manufacturers make a mistake. How about the thousands of PEDs out there that have not been and will never be tested? Should someone playing with their PDA in the lavatory cause a lav smoke warning?
 
iakobos
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RE: Using GPS Onboard Aircraft?

Wed Dec 08, 2004 7:18 am

Thanks for the lav story (no surprise to me though) but I was hoping you would have had something closer to the point.

From NASA - Langley Research center
cf "it is reasonable to suspect that certain new technology transmitters may be no more threatening to a/c systems than unintentional transmitters (which pax may legally use onboard a/c with certain restrictions)"
underlines are mine.

re Fluo lamps
I guess you are aware that gas filled lamps do radiate over a very wide frequency spectrum, due to the ionization of the gas. Defective ballast or not, it does not matter, the lamp radiates, and quite a lot at that.
Unless you find a way to shield a lamp and still benefit from its intended lighting capabilities, this is the perfect example of a BAD non-intentional radiating device, and there are many on a/c.
What do you intend to suggest with "scrutiny they are put under" ?

Sure you know the story about Boeing flying on purpose a 747 with 242 laptops onboard in order to test the susceptibility of the a/c systems.
What was the conclusion ?

Your own words:
* And proceed to make the choice for all aboard to endanger their lives while you play with your unauthorized toy....
* I have witnessed interference with aircraft systems from all sorts of devices including unintentional radiators like hand-held GPS receivers
*...from many sources including portable electronics devices typically operated by passengers. These devices however are the worst.

No, I have no appetite for controversy, I simply believe that you overreacted and went a little bit hyperbolic in this post.

Without any PED on an a/c there is already more than enough to be concerned of in terms of EMI and RFI.
Aircraft systems self-generated EM and RF interferences are higher than any (unintentionally radiating) PED's interference.
Am I wrong ?


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