Ask the Captain: A reader challenges in-flight electronics rules
— -- Question: Hello Captain Cox. I've read your past columns regarding the use of electronic devices. I would like to share with you some observations I have made while flying and get your input.
1) Regarding the use of electronic book readers: Most of the devices that I use such as a Kindle and iPad have their wireless capability disabled. I would challenge your assertion that they have the capability to interfere with in flight instrumentation. The available studies I have been able to find on the Internet show that the EMF emissions on these devices is very low. Lower in fact than the typical EMF emissions of the incandescent light bulbs used in the reading lights on airplanes.
2) As far as the devices with wireless turned on, a congressional study a few years ago sought to determine if these types of devices were a threat to commercial aviation. They were unable to find any verifiable incident where a wireless device (cellphone, etc.) had interfered with the instrumentation on a commercial aircraft. There was one anecdotal report of pilots reporting interference with their instruments. After that plane landed, it was discovered that there was a laptop in a passenger's in-cabin luggage that was turned on with its wireless capability enabled. Boeing subsequently purchased the laptop from the passenger and was unable to recreate the interference with instrumentation using the purchased laptop in a controlled setting.
3) I recently had the opportunity to sit next to an American MD-80 pilot (whom I discovered had been two classes ahead of me at the Air Force Academy). When we started discussing the subject of interference from in-flight usage of wireless devices, he expressed to me that there was no way they could interfere with modern instrumentation used in today's aircraft.
4) I have observed on the American flights with Wi-Fi available that the GoGo inflight wireless access points are enabled throughout the flight. From the moment the aircraft is started at the gate all the way through landing and taxiing to the gate, these wireless access points are continuously operating and emitting their wireless signals. This would seem to contradict the assertion that this type of RF transmission could interfere with in-flight instrumentation.
5) If these types of emissions are so harmful to sensitive flight instruments, then why are the general public allowed to hold them right next to their skulls near their brain for extended periods of time?
6) If the instrumentation on an aircraft is so sensitive to emissions from a low power emissions source like a cellphone or laptop that it could potentially interfere with their operation, wouldn't it be subject to much stronger sources of EMF interference like a lightning strike?
7) FAA studies have shown that the average aircraft takes off with a minimum of 4 cellphones on every flight. If this is the case then why have we not seen any reports of airplane crashes or other types of incidents attributed to interference from an enabled wireless device onboard?
-- submitted by reader Kelly Clark
Answer: You raise an issue that we have discussed several times previously. The concern of the FAA is that an electronic emitter could cause unintended consequences to navigation receivers or other aircraft systems. Does this mean that an iPad in airplane mode is a threat? Probably not, but the ongoing changes in electronics make it very difficult to test all the devices to ensure their safety.
Are there some devices that can interfere? Yes, transmitters used to control toy cars or boats are known problems. Radio transmitters such as short-range radios (walkie-talkies) can cause issues. There are others.
Several years ago a computer was found to cause a problem on a European flight. The regulatory agency involved studied it to learn how it could cause the problem. I do not know of any other cases of a computer causing a problem, but there remains understandable concern.
Respectfully, I disagree with the pilot you spoke with. During some phases of flight the navigation system is more sensitive than others. An example is during an approach for landing using the Instrument Landing System (ILS). The display uses microvolts to displace a needle showing the extended centerline of the runway. As the airplane flies the ILS course, the needle becomes more sensitive (think of it as a cone with the top of the cone at the runway).
There are numerous anecdotal reports of electronic interference. The validity of these reports varies. I do not know of any empirical study that has found specific devices causing specific problems on specific flights. However, The FAA has to take all the reports seriously.
Your question regarding the correlation between electronic emissions being held close to the head and electronic interference is an apple and oranges comparison. The question is how the airplane could react to the signal, not a human.
Lightning strike protection is part of the certification process for all airplanes. By properly grounding the airplane, damage caused by a strike is minimal (I have been in airplanes that have been struck by lightning several times with no damage). The time of the strike is very short and usually not during the approach phase of flight. Once the lightning is dissipated, there are no residual effects. An onboard electronic emitter can transmit for a long time causing ongoing problems. The issues are very different.
I have not seen any FAA study reporting that four cellphones are operating in flight. Cellphones that are not active (transmitting) emit much lower power. In the U.S., use of a cellphone in flight is prohibited and flight attendants enforce the rule. Therefore, I would not expect any cellphones to be active in flight.
The core of the issue of the use of electronic devices in flight is the ability to certify the devices as safe. The FAA has developed criteria for electronic devices proving their safety. The operators have the ability to get certain electronic devices certified for use in flight. It is much more difficult for the FAA to evaluate the effects of the use of untested electronics. This is why they have the ban on all electronic devices below 10,000 feet.
John Cox is a retired airline captain with U.S. Airways and runs his own aviation safety consulting company, Safety Operating Systems.