Banana Skins – June 2019 (#188-197)

188. Another aviation incident taken from the NASA ASRS PED report

Aircraft: DC9. During CLBOUT from BDL, the captain’s radar altimeter flagged and the TCASII and GPWS subsequently annunciated ‘FAIL’. The problem continued throughout the CLB to FL350 whereupon I had time to ask a flight attendant to do a PAX electronic device walk. She discovered that a Sony Video Walkman was in use in seat XX. After the Sony was shut off, the problems cleared up. The item was a Sony GVA-500 Video Walkman.

(From Gary Fenical of Laird Technologies, USA, http://www.lairdtech.com.)

189. Just one more aviation incident taken from the NASA ASRS PED report

Aircraft: Brasilia EMB120. I experienced interference with VOR navigation reception. We found a PAX in seat XA operating a 300MHz Toshiba Protégé Laptop computer. We had her discontinue the use of the computer and normal reception was restored. I have had previous problems with Toshiba computers that are used in row X. I will not limit the use of PAX electronic devices yet, however I now immediately check to se if a laptop is on when experiencing navigation problems.

Callback conversation with the reporter revealed the following info: the reporter stated that the same exact incident happened on a different EMB120 at row X and with a Toshiba laptop computer. That time, they were at McAllister VOR, when the needles on the MFD (Multifunction display) went crazy and were spinning in circles. In both cases, it was spinning in circles on both NAV1 and NAV2. The reporter guessed it was a laptop computer causing it and had the flight attendant check it out and had the person turn it back on to see what would happen, and the instruments resumed almost a normal position , but it was 40 degrees off from ATC.

He said row X is the first row behind the trailing edge of the wing. With this particular incident, he is 90 percent sure that the PAX did turn her computer back on afterwards, but they were almost on top of the new VOR, so he believes that’s why it didn’t interfere again with the navigation. The reporter speculates that perhaps the Toshiba laptop computer and the VOR had the same or similar frequencies.

(From Gary Fenical of Laird Technologies, USA, http://www.lairdtech.com.)

190. Pop-up toasters in Dorset speak Russian

Villagers in Dorset were baffled when their pop-up toasters began to speak Russian. Phones and other electrical appliances in Hooke also chatter away in foreign languages and play music. The phenomenon has been blamed on a powerful radio transmitter in nearby Rampisham that transmits BBC World Service.

John Dalton, chairman of the parish council, says: “I’ve heard foreign voices through an electric organ. And I was amazed when I got the World Service signature tune through a toaster.”

(From “Weirdness of the Week” in the Sunday Times’ ‘News Review,’ 12th May 2002, page 4.12, http://www.sunday-times.co.uk.)

191. ITV Digital alleged killed by government restrictions on transmitter power

“The basic problem was that the black boxes didn’t work. The signal was weak because civil servants were frightened to interfere with signals for conventional television and mobile phones. So screens would go fuzzy during a drama’s crucial kiss or freeze just before the winning goal.”  Green groans. “This is not an excuse but if I did it again, I would check all the technology worked first.

“We were promised extensive coverage but it was like Swiss cheese. One side of the street would receive a signal but not the other. It made marketing hopeless. When I went into my local Dixons in the country, they said that I couldn’t get digital but my box worked fine. It’s remarkable we got 1.2 million viewers, it was such a farce.”

Didn’t he try to get the signal turned up? “There is no question but that this Government was useless. I went so many times to Chris Smith, Tessa Jowell, and Tony Blair, saying: ‘We’re losing £1 million a day, please turn up the signal. You never told us it wouldn’t work: it’s softer than an electric razor.’ The Government shouldn’t have to interfere but they sold us a dud product.”

(From “Is ITV Digital a mess? Yes. Did we make mistakes? Definitely,” an interview with Michael Green, chairman of Carlton Communications in The Daily Telegraph, Saturday May 4th 2002, Page 10, http://www.telegraph.co.uk. This was just after ITV Digital closed down with a financial loss of about £600 million with 1700 people losing their jobs.)

192. More on the demise of ITV Digital

The main problem with ITV Digital is that its technology did not work. It was inferior to rival offerings from satellite and cable. The signal had to be transmitted at low strength, otherwise it interfered with mobile phones and even French television. The result was only half the country was covered, and the service was unreliable.

The Government failed to sort out the different regulators, such as the Radio Authority  and the Radio Communications Agency, which dragged  their feet in allowing ITV Digital to turn up its signal.

(Two extracts from “How the digital dream became a nightmare,” The Daily Telegraph, Saturday May 4th 2002, page 11, http://www.telegraph.co.uk.)

193. Walkie talkie interferes with gas detector, puts lives at risk

A portable gas detector failed without the operator noticing when used near a handheld radio transmitter. The equipment was being used to protect people involved with sewer repair work from the effects of toxic gases. The electric field strength from the transmitter may locally have exceeded the proposed (at that time – Editor) industrial generic immunity level of 10 V/m. This is an example where equipment, which may have conformed to a standard, was apparently not immune to interference in use. It was subsequently modified to include an additional screen.

(From “Dangers of Interference, EMC and Safety” by Simon Brown of the UK’s Health and Safety Executive, in the IEE Review’s EMC Supplement July 1994 page S-11, http://www.theiet.org.)

194. Poorly bonded aircraft surfaces cause loss of navigation and communication in rain (1)

A pilot complained about navigation and communication equipment on his plane becoming inoperable when flying through rain. Studies have shown that when an aircraft flies through rain, static electricity on the aircraft skin can exceed 100,000 volts. In the hanger, testers simulated this situation by isolating the aircraft from ground. Using a high voltage power supply they charged the aircraft to approximately 100,000 volts. A portable RF receiver was used to locate the source of broadband RF noise. It turned out to be arcing between poorly bonded aircraft surfaces.

(From “The Case for Combining EMC and Environmental Testing,” by W H Parker W Tustin and T Masone.)

195. Poorly bonded aircraft surfaces cause loss of navigation and communication in rain (2)

Author Masone recalls a flight test to document a similar problem. The test involved flying EMI specialists into a storm. Immediately upon entering the storm, Masone heard a high-pitched squealing sound from the pilot’s headset. Its intensity was such that the pilot had to remove his headset. The navigation display then went black. All navigation and communication equipment was inoperable in a whiteout condition with freezing rain and snow! Fortunately, the pilot was experienced, and there were no other aircraft in the flight path.

Upon exiting the storm, all navigation and communication functions returned to normal operation. Back at the hangar, high voltage testing led to the discovery of a poor bond between two surfaces on the horizontal stabilizer.

(From “The case for combining EMC and environmental testing,” by W H Parker W Tustin and T Masone, ITEM 2002, pages 54-60.)

196. Flying too close to radio masts has in the past brought down military aircraft

The system is also immune to electromagnetic interference, unlike other methods of computer control. Flying too close to civilian radio masts, for instance, has in the past brought down military aircraft.

(From “Fibre Optics to Aid Helicopter Safety” by Rob Coppinger, The Engineer, 19 April 2002, page 11, http://www.theengineer.co.uk.)

197. Guide on proximity of wireless communications to pacemakers

The Pacemaker Committee of Japan issued the following guidelines at March 1996…Keep handy cellphones (and PHS, cordless phones, etc.) away at least 22cm from the implanted pacemakers. When using such devices, patient should use the ear at the opposite side of his pacemaker. Stay at least 30cm from antennas of land mobile radiotelephones and shoulder radiotelephones. Patients shouldn’t use other radio transmitters such as amateur radios, walkie-talkies (excluding that with extra-low power), etc. This committee is a conference group in Japan Association of Medical Equipment Industries (JAMEI).

(From Tom Sato, Jun 02.)


The regular “Banana Skins” column was published in the EMC Journal, starting in January 1998. Alan E. Hutley, a prominent member of the electronics community, distinguished publisher of the EMC Journal, founder of the EMCIA EMC Industry Association and the EMCUK Exhibition & Conference, has graciously given his permission for In Compliance to republish this reader-favorite column.

The Banana Skin columns were compiled by Keith Armstrong, of Cherry Clough Consultants Ltd, from items he found in various publications, and anecdotes and links sent in by the many fans of the column. All of the EMC Journal columns are available at: https://www.emcstandards.co.uk/emi-stories, indexed both by application and type of EM disturbance, and new ones have recently begun being added. Keith has also given his permission for these stories to be shared through In Compliance as a service to the worldwide EMC community.

We are proud to carry on the tradition of sharing Banana Skins for the purpose of promoting education for EMI/EMC engineers.

About The Author

Keith Armstrong

After working as an electronic designer, then project manager and design department manager, Keith started Cherry Clough Consultants in 1990 to help companies reduce financial risks and project timescales through the use of proven good EMC engineering practices. Over the last 20 years, Keith has presented many papers, demonstrations, and training courses on good EMC engineering techniques and on EMC for Functional Safety, worldwide, and also written very many articles on these topics. He chairs the IET’s Working Group on EMC for Functional Safety, and is the UK Government’s appointed expert to the IEC committees working on 61000-1-2 (EMC & Functional Safety), 60601-1-2 (EMC for Medical Devices), and 61000-6-7 (Generic standard on EMC & Functional Safety).

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