Why do devices need to be qualified for use on the Flight Line?

If you’ve ever been on an aeroplane, you will undoubtedly have been told by the flight attendants to turn off any portable electronics or at the very least put them into a ‘flight safe’ mode. This request is made as part of the safety briefing at the start and end of flights so that the devices don’t interfere with the aircraft operations at what is arguably the most important part of a flight; the ascent and descent are the most complex manoeuvres after all.

Now, if you were to ask any of the passengers on board why we are told to turn our mobile devices off you would get a wide range of responses varying from ‘if we don’t, the plane is going to fall out of the sky’ to ‘oh it’s all just a fad and doesn’t make any difference’.

I must admit, I was previously in the second camp here. I thought the task was purely a box-ticking exercise, similar to asking people to read the safety information in the seat pocket in front of you – the request is made but the number of people who actually read the pamphlet can probably be counted on one hand. The flight attendants know that most aren’t going to read it but they’ve done their part so legally they are in the clear should something go wrong. I assumed that asking people to turn off their mobile devices or put them into a ‘flight safe’ mode was made in a similar vein. It wasn’t until I learned about EMC profiles and how electronic devices can interact with one another, even when there is no clear connection, that I realised there was a real, tangible reason behind the request.

Thankfully the chances of interference from phones and other mobile devices bringing down the aircraft you’re sat on are almost infinitesimal, so you can relax a little should you forget to turn your phone off during your next flight. Considering that standard commercially focused devices have an EMC profile equivalent to dropping into a battlefield with a giant ‘I’m here’ sign illuminating you, this is very good news. So why do we have to turn our devices off while on an aircraft?

Well, while they might not cause any specific damage to the aircraft, commercial devices are typically very ‘noisy’. By this, I mean that they give off a high level of electromagnetic interference, which, when placed in an environment that requires a very particular set of electronics to work in a very specific way, can have less than desirable effects.

What makes an electronic device ‘Noisy’?

Naturally, when we hear the word ‘noise’ we are immediately drawn to think of something audible that we can physically hear, which would be correct in most situations. In this context however, it is a bit different. When we are talking about devices being ‘noisy’ we are referring to the amount of Electromagnetic interference that a device produces while in various states of operation. In other words, we are talking about its EMC profile (also known as Electromagnetic Compatibility). If you want to learn more about EMC and how to test for it, you can read an article we have written on the subject here.

The EMC level of electronic devices and therefore the amount of ‘noise’ a device produces is dependent on many factors. For simplicities sake, however, we will narrow it down to 3 main contributors:

  1. Materials – The materials that are used in the manufacturing process will alter a devices EMC profile significantly as each material will have different levels of conductivity, producing more or less electromagnetic forces depending on the material.
  2. The intended purpose of the device – The intended purpose of the device plays a part due to the level of required connectivity a device needs. A device that requires lots of open ports and connections (Internet, Bluetooth etc.) is going to have a “noisier” EMC profile than one that only has a singular port with no open or active connections.
  3. Sealing – How the device is sealed and the quality of that sealing will alter the EMC profile because gaps in any EMC seal can cause the emissions to leak into the surrounding environment.

Why does it matter?

If a device is noisy or has a poor EMC profile, it is going to be emitting a lot of electromagnetic radiation into whatever environment it is placed in. These emissions can and most likely will interfere with all the other electronics in the vicinity, which when dealing with highly sensitive equipment or systems (such as those present on an aircraft) can create unintended and most definitely unwanted problems.

Any commercial mobile device that is brought on board an aircraft is kept a considerable distance away from any sensitive electronics, in part due to the way aircraft are designed with passengers separated from any control mechanisms. Because of this, they are not held to the same standards as devices that are in the direct presence or close proximity of these sensitive systems. For example, a server or processor that is used as part of the navigation system would have to pass much more stringent regulations before it is even considered for use. If there were no regulations in place and a server with a poor EMC profile was used, then the emissions from that server would interfere with every other electronic device and potentially cause it to function incorrectly. In addition, emissions from other equipment on board could interfere with the server with possible issues ranging from delays in GPS tracking to parts of the system failing due to electromagnetic interference.

With that in mind, it becomes clearer why devices used in aircraft or on the flight line need to be adequately qualified for their intended use. If we need to take steps to ensure our mobile devices are put into a flight safe mode for the short time they are on an aircraft, due to risk of interference, then the electronics that are present continuously need to be built in such a way that ensures they do not interfere with any of the other intricate electronics on board, of which there are thousands.

Thankfully there has been countless hours of testing done by manufacturers and engineers over the last few decades with one singular purpose; discover what level of EMC profile is ‘safe for use’ on the Flight Line and come up with a very strict set of regulations that must be adhered to if a manufacturer wants their products to be used in these environments.

Here at GRiD, our products are deployed in a number of different environments so we take our products through rigorous testing and build our devices to EMC standards for both Military (Mil-STD-461) and Defence (Def Stan 59-411). Meaning that, among a host of other certifications, our products are qualified for use on the Flight Line due to their very low EMC Profile.

If you are interested in learning more about how we ensure our devices are qualified for the Flight Line and the benefits of doing so then give our team a call on +44 (0)1628 810 230 or drop an email to sales@griduk.com