Switch Off Your Cell Phones!

This posting is dedicated to all those people that refuse to follow the security instructions to turn off their cell phones during flight! (Scroll to the end for incidents reported by pilots.)

You want a safe flight, you want to arrive safely at your destination, you even clap after landing but you accept to risk your life and the life of all others just because of some unimportant calls or stupid text messages or just because playing around with it to kill time!?

What’s wrong with you people?

Why do you ignore the instructions to turn your cell phone off? Why do you think those announcements are beeing made? Just to annoy you?

Think again!

Let’s do a little test. Turn on your cell phone and place it near your speakers or stereo. Now wait a few minutes. Hear the annoying static-y clicking noise? What if I tell you that the pilots do hear the same annyoing static-y clicking noise in their headsets? Constantly. Interrupting the radio transmissions! The radio transmissions that define position, altitude, speed, traffic sights. The radio transmissions that are inalienable to provide a safe flight.

You think your seat is placed far enough away from the cockpit? Wrong! Sensitive systems are placed everywhere throughout the aircraft. Even if placed in the overhead compartment it’s only one foot away from top of the fuselage, where most of the antennas are mounted! Again, it’s not only interfering with radio devices it’s interfering with the whole electronic system. And not only Cell Phones are interfering! Even Laptops, Portable Electronic Game Devices (Gameboy, Nintendo DS, PSP), Radios, CD Players, MP3 Players, Movie Players, Pagers and Handhelds!

This year in January a Boeing 737-400 over Europe lost most of it’s intruments, autopilot changed heading by it’s own to a wrong direction, increased altitude by it’s own and could not be switched off. Navigation instruments showed wrong data and the crew lost control of the airplane. The whole electronic system acted up! 5 times the announcement to switch off cell phones was repeated, and was just ignored! Then the flight attendants checked the passengers and found some guy texting. They switched it off and all the problems were gone! The crew gained back control and all systems worked normally again.

Do you want this to happen to your next flight?

How about some statistics?

Top affected aircraft systems
1. Navigation
2. Communications
3. Autopilot
4. Yaw Dampers
5. Engine Fuel Control
6. Speed Brake Auto Deploy
7. Autothrottles

When incidents occurred
53% Enroute/Cruise
26% Approach/Landing
18% Takeoff/Climbout
3% On Ground

In which altitude
62% 10000 ft or more
38% Less than 10000 ft

Discovered by
76% Flight Crew
24% Air Traffic Control

“But I’m only texting” – It doesn’t matter what you are doing! If it’s ON it’s interfering and so it’s a security concern!

“But my cell phone has an integrated MP3 player I want to use” – If your cell phone doesn’t have a “Flight Mode” you can’t use it and you need to turn it off completely. If your cell phone does have a “Flight Mode” you need to activate that mode! Using this setting all phone functions are beeing disabled and it’s safe to use the MP3 player or play games. But you need to activate this mode, it doesn’t do it by it’s own!

“My seat neighbor is using his phone, what should I do?” – Tell a Flight Attendant. They will appreciate your notice.

So, next time you fly, don’t be an ignorant dork, follow all instructions and turn your phone off during the whole flight.

After I made this blog post, I received a few messages from some people, claiming the information to be wrong or urban myth. Let me add some lines to clarify:

  • Some time ago I personally heared reports from some pilots about cell phones causing abnormal behavior of aircraft systems and how they had to deal with passengers not willing to stop using it according to the security guidelines.
  • These true(!) stories made me write this article.
  • The primary information in this article is based on several proven reports and information provided by airline pilots.
  • The statistics and facts are based on research made by NASA.
  • Interferences of electronic devices with aircraft systems have been proven by Boeing
  • Federal Communications Commission (FCC) rules prohibit the use of cellular phones and other wireless devices on airborne aircraft. This ban was put in place because of potential interference to wireless networks on the ground.

    In March 2007, the FCC terminated a proceeding that it began in late 2004 to consider potentially lifting this ban. The FCC determined that the technical information provided by interested parties in response to the proposal was insufficient to determine whether in-flight use of wireless devices on aircraft could cause harmful interference to wireless networks on the ground. Therefore, it decided at this time to make no changes in the rules prohibiting in-flight use of such devices.

    In addition to the FCC’s rules, the Federal Aviation Administration (FAA) prohibits in-flight use of wireless devices because of potential interference to the aircraft’s navigation and communication systems. For this same reason the FAA also regulates the use of all portable electronic devices (PEDs), such as iPods and portable DVD players, during flight.

    The FCC has approved rules that allow in-flight voice and data services, including broadband services using dedicated air-to-ground frequencies that were previously used for seat-back telephone service. Air-to-ground service providers are in the process of rolling out new in-flight services, such as high-speed Internet access for laptop computers. Because these services will operate in frequencies that are dedicated to air-to-ground communications and are separate from those used for wireless services on the ground, they do not pose an interference risk to wireless networks on the ground. Providers of in-flight wireless broadband and other communications services using the air-to-ground frequencies must coordinate with airlines and comply with any FAA rules in order to offer such services.

  • The FAA published an advisory. “… These include cellular telephones, citizens band radios, remote control devices, computers with wireless network capabilities, and other wireless-enabled devices such as PDAs, etc. The Federal Communications Commission (FCC) currently prohibits the use of cell phones while airborne. Its primary concern is that a cell phone, used while airborne, would have a much greater transmitting range than a land mobile unit. Their use could result in unwanted interference to transmissions at other cell locations since the system uses the same frequency several times within a market or given operating area. Since a cell phone is capable of operating on various cellular frequencies, unwanted interference may also affect cellular systems in adjacent markets or operating areas.

    b. The FAA supports this airborne restriction for other reasons of potential interference to aircraft systems and equipment. Currently, the FAA does not prohibit the use of certain cell phones in aircraft while on the ground. An example might be their use at the gate or during an extended wait on the ground while awaiting a gate, when specifically authorized by the operator. A cell phone will not be authorized for use while the aircraft is being taxied for departure after leaving the gate. The unit will be turned off and properly stowed to prepare the aircraft for takeoff as per the operator’s procedures. Whatever procedures an operator elects to adopt should be clearly spelled out in oral briefings prior to departure or by written material provided to each passenger.”

  • Of course not every use of a cell phone or other electronic device leads to a serious incident. It’s a matter of several unknown factors. That’s why their use is generally prohibited and not just eq. on particular seats.
  • If you still don’t believe, it’s a matter of your ignorance, not a matter of facts.

For those still unwilling to accept that cell phones present a potential hazard, here are some examples of cell phone interferences with aircraft systems – source FAA, NTSB, NASA & other research organisations:

Pilot of a B737, flying for a major US carrier

  • “[…] One day departing Portland Oregon we noted that the FMC [Flight Management Computer] Map display showed a disagreement with the “raw data” VOR position. Our training is such that we would normally immediately switch over to “raw data” and assume the FMC was in error.

    We would have done that except that it was a beautifully clear day and I looked out the window and was able to determine that the FMC seemed to be right on. I called back to the cabin and asked the flight attendants to check for someone using a cell phone or computer. A few minutes later they called back to say that a man had been using his cell phone and it was now off. Strangely (?) our VOR and FMC map now agreed.”

Pilot of a B737, flying for a major European carrier

  • “In our company we recently had a Localizer deviation (out of tolerances) on a B737-200 related to a GSM (mobile phone) being operated by a passenger (who was disregarding our company regulations). When requested by the cabin crew to switch off his GSM, localizer indications became normal. Is this scientific proof? Certainly not, but good enough for me as a captain to insist that all the electronic toys, computers, mobile phones, etc., are OFF during critical phases of flight. […]
  • I had fuel indications on the FMC going crazy on board the B737, that returned to normal when all electronic stuff in the back was switched off. I suspect a “Gameboy” electronic game device to have interfered, but this is no more than a guess. No, I did not ask to switch the toy back on again and investigate more in depth as I was responsible for the safety of 140 passengers and this would have been extremely irresponsible! This is not a situation in which to do such testing! This [ever-present responsibility accounts for why] there is no “proof” of the relationship.
  • I also recall experiencing *impossible* mode annunciations on the FMA (flight mode annunciator) on B737. Having both the autothrottle AND the pitch channel of the autopilot trying to maintain speed (both in MCP SPD mode) for example, not programmed by the pilot (you cannot program that). After an expensive in-depth troubleshooting session by our maintenance department, the incompatible mode annunciations were traced to a … faulty cockpit window heat wiring. This caused electronic interference with the auto flight system.
  • B737-300: *Verify position* was indicated on the CDU. Both IRS and radio position were correct, the FMC position was not. The difference rapidly increased to 8 nautical miles. After switching a GSM in the cabin from STBY to OFF, the FMC updated normally. FMC was correct for the remainder of the flight and on the return flight.
  • B737-400: During level cruise, the AP pitched up and down with ROC/ROD of 400 fpm indicated. Other AP was selected: no change. Cabin was checked for PC’s and other electronic devices: nothing was found. Requested passengers to verify that their mobile phone (GSM) was switched OFF. Soon after this request all pitch oscillations stopped.
  • B737-200: During approach to MAN (Manchester International, UK), the LOC for landing runway 24 oscillated and centered with the aircraft not on track (but offset), confirmed visually. Ground equipment was monitored and working normally. When a GSM in the cabin was switched off, all indications became correct.”

NASA Research

  • Boeing 757, flying from Seattle to Covington/Cincinnati, experienced loss of all three of its autopilot systems. Flight attendants checked for a passenger using a portable electronic device and discovered a man wearing headphones, which were part of a hearing aid. The passenger was allowed to continue using the device, but was moved forward several rows. The autopilot system then regained full operational capabilities and was later checked by maintenance, with no problems being found.
  • A Cessna 340/A pilot experienced erroneous readings when attempting to determine his location because of a passenger using a cellular phone. After the passenger turned off the phone, the pilot was able to locate his position and continue on with no problems.
  • A regional jet was flying from Salt Lake City to Eugene. The flight crew received three separate warning messages stating that there were disagreements between the captain’s and the first officer’s instruments. The three warnings were for discrepancies in heading, airspeed, and altitude indicators. After flight attendants checked the cabin for passengers using portable electronic devices and had the devices turned off, all problems ceased.
  • An aircraft making its approach to George Bush Intercontinental Airport in Houston was advised that it was 4 miles off course. Because the course director indicators had been scalloping left and right of center, the captain ordered the flight attendant to check the cabin for any passengers using a portable electronic device. Within 15 seconds, problems with the course director indicators disappeared. The captain later learned that a passenger had been using a portable computer.
  • The electric compass indicators of the first officer of a Boeing 737 gave erratic readings. After a sweep of the cabin was made for portable electronic devices, which resulted in flight attendants asking a passenger to turn off a compact disc player, the first officer’s instruments returned to normal working order.
  • Shortly after takeoff from Baltimore, an aircraft was advised by ground control that it was 10 miles off course, though the plane’s instruments indicated nothing abnormal. It was found that a passenger in first class was using a portable computer. After the computer was turned off, navigation instruments returned to normal.
  • A turboprop aircraft flying government officials from Lake Havasu, AZ to Yuma, AZ experienced trouble with its navigational radios. Ground control showed that the airplane was off course and gave corrections. However, the plane’s navigation system had been checked earlier in the month and was said to have zero error. After the flight, the pilot learned that at least one passenger was using a cellular phone while the plane was in the air.
  • A turbojet aircraft was notified three times, by two different control towers, that it looked to be off course. All instruments in the cockpit were showing the plane’s position to be correct. Flight attendants searched for portable electronic devices and found a tape machine and a hand-held video game unit in use. The devices were turned off and there were no other navigational discrepancies during the flight.
  • A plane travelling from Boston to Youngstown/Warren, OH was advised it was off course and was issued a new heading. The plane’s navigational instruments showed it to be on course. After checking the cabin for portable electronic devices, the lead flight attendant informed the captain that 23 passengers were using AM/FM cassette players and one passenger was using a personal computer. The passengers were asked to turn off the devices and the flight proceeded without further incident.

NASA research: NASA Personal Electronic Devices and Their Interference with Aircraft Systems
Boeing: Interference from Electronic Devices
German research: Electromagnetic Interference with Aircraft Systems: why worry?

5 thoughts on “Switch Off Your Cell Phones!”

  1. I think you need to either learn some electronic engineering, or pickup the IEEE Spectrum magazine.

    Electromagnetic communications systems are designed to use frequencies that don’t interfere with
    each other at reasonable distances. Every product sold has to undergo a grueling process to
    ensure this. I’ve been through it and it’s a major pain in the ass. An article about two years
    ago in IEEE Spectrum magaine gave a complete breakdown of the frequencies used by navigation equipment and proved that they’re not the same as those used by cell phones.

    Don’t you think if cell phones really interfered with nav equipment, then all the activity on the
    ground would have some effect? I communicate regularly with DSP engineers who design communications equipment. They’re competent people who know what they’re doing. Do you think it’s just an accident that the frequencies don’t overlap? Not at all. It’s the result of cooperation and coordination by intelligent people and regulated and monitored by the FCC.

    Don’t you think there would be many more problems if cell phones interfered with airplane navigation equipment? There are many other, more significant sources of EMF interference in the air, such as lightning, clouds of ions, and yes, even the sun and other cosmic rays. These sources change rapidly with local atmospheric conditions, but nav/comm systems are designed to work in the presence of such interference. I don’t buy your texting story for a second. The amount of bandwidth texting uses is TINY. Each text message requires a millisecond burst of interference. Even if it were directly jamming on the same frequency as nav/comm equipment, the equipment would recover very quickly.

    Some airplanes even have Wi-Fi on them. How do you think that works?

    In conclusion, the word “security” is not some magic word that you can use to get people to do whatever you want. It’s more like a word you use to betray your lack of technical knowledge and your own fear. If you look around, you’ll find there are two main reasons why cell phones aren’t allowed in flight. It’s because 1) the extra bandwidth used for connecting to rapidly changing towers while moving at high speed makes the tower bandwidth less efficiently utilized, meaning more busy circuits and less revenue for cell phone companies. 2) airlines don’t want to have to deal with noisy passengers on cell phones. For the record, I sympathize with both of these reasons and see them as legitimate concerns.

  2. So you’re saying that reports about interferences of electronic devices with aircraft systems made by NASA are wrong?! That several investigated reports by pilots, cabin crew and ATC are wrong?

    Might be your opinion, I better believe proven facts and reports by pilots and flight crew who has to deal with it every day and know what they are talking about, than some random guy posting a anonymous comment and probably never has been in a cockpit.

  3. As an ailine pilot, I have heard the interference in my headset just like the author describes it however, I have never experiened any problems of any kind with either my navigation instruments or my communication radios.

    The electronic noise that the author talks about has never been loud enough to interfere with my radio communications.

    As a profesional airline pilot, I always comply with both the Federal Aviation Regulations and the Federal Communications Regulations eventhough there are no conclusive reports of any kind that confirm that the use of cell phones aboard an aircraft is actually dangerous.

    There is extensive talk about airlines getting a cut from the usage of air phones installed in their aircraft (which is true). Also, there is plenty of talk about niether the government nor the aircraft and airline industries getting involved in any major studies about the subject, since it doesn’t yield any financial benefits for any of them.

    The FCC has recently been considering lifting some of the bans on cell phone usage aboard aircraft under certain conditions, and the FAA allows their use aboard aircraft operating under VFR.

    Before anyone writes an article or makes a comment about an article on this subject, better get some real knowledge about it before doing so. The government has actually come up with these regulations because they don’t know for sure weather cell phones are actually dangerous when used aboard an aircraft.

    With a Bachelor of Science in Aeronautical Science From Embry-Riddle Aeronautical University and 27 years of experience in the field, I know I am sure about what i am talking about.

  4. To me on 18 May 2007,

    You are right in that there are some spectrum management to separate different applications to different bands. However, intermodulation can occur. De-sensing can occur. Human errors in maintenance can occur (resulting in poor shielding/grounding)… just to name a few.

    Indeed, when there is “cooperation and coordination by intelligent people and regulated and monitored by the FCC”, there should be very little we need to worry about. However, what if some joker bought a handphone in some don’t-know-what-country? What if that particular model do not meet FCC requirement? What if the aircraft designer/engineer just meet the requirement?

    What ever the case may be, do you want to take the risk? For the benefit of a phone call or SMS?