Friday, August 28, 2015

Airplane Mode 2015

UPDATE 24 Sep - Here is the current issue list:

* Should (Wi-Fi, Bluetooth, GPS) stay on when engaging Airplane Mode?

* How can a mobile client application become aware of Airplane Mode?

* How can the network command "mute/pause" during Passenger Address?

* How should a laptop operating system accommodate an Airplane Mode?

* Should the user have control settings to manage/monitor how each network is utilized?

* How should Airplane Mode recommendations be developed and approved?

* Should the local access point have a protocol to convey maximum streaming rate, relative cost, and network quality of service level?

* Should a special "Cellular Airplane Mode" used with picocells provide overarching EIRP limits or any other useful information?


Qualcomm claims to have invented "airplane mode" by the year 2000.

Airplane connectivity has certainly changed dramatically in the last 15 years.  We are now welcome to use portable electronic devices (PED) seamlessly from "gate to gate".
From the FAA:
Cell phones should be in airplane mode or with cellular service disabled     
- i.e., no signal bars displayed    
- cannot be used for voice communications 
(based on FCC regulations that prohibit any airborne calls using cell phones.)    
If your air carrier provides Wi-Fi service during flight, you may use those services.   
You can also continue to use short-range Bluetooth accessories, like wireless keyboards.
Here is the list of permitted portable electronic devices, from Delta Airlines as an example:
• AM/FM or satellite radios
• digital and video cameras
• calculators
• Delta-installed equipment such as in-flight entertainment systems
• DVD players*
• e-readers
• electric shavers
• electronic/digital watches
• global positioning system (GPS) receivers
• handheld computer games
• headphones
• laptop computers*
• medical devices**
• noise reduction headphones
• portable media players*
• pagers
• tablets and wireless keyboards or mouse
• smartphones and any device with cellular network service must be turned off
or in airplane mode

Refer to the attachment, below, to better understand how PED Tolerance and Airplane Mode are defined and related to each other.

Airplane Mode 2015 - to carry us the next 15 years

The original, and foremost purpose of airplane mode is to mute any emissions that might interfere with airplane systems.  That is generally assumed to be just cellular (speaking about public services).

Most devices will turn off all radio services when going into airplane mode.  The user is then given the option to turn Wi-Fi or Bluetooth back on, while in airplane mode.

Another factor is how applications manage use of connectivity.  Many applications will limit their network demand when on cellular.  Pretty much all applications assume Wi-Fi has no limits.

Aviation satellite terminals are inherently disadvantaged, which makes them more expensive to operate than what you might find at an airport or hotel.

Gogo operates a network of ground stations that is also quite disadvantaged when compared to cellular services.

Can we agree to treat Wi-Fi while in airplane mode the same as cellular - applying a stingy profile to any use of the network?

Let's not update software or data bases while we are in airplane mode.  Do whatever you can to minimize the network use.

Leave Wi-Fi or Bluetooth radios on if you believe them to be safe; don't switch them off when engaging airplane mode.  The user can manually shut down their device if an issue arises.

Could the Wi-Fi access point provide some signal to attached devices defining local (and temporal) streaming limits and for overall service level (low, med, unlimited resolution)?  The access point could suggest to stream at a given maximum rate, commanding everyone's devices to harmonize their viewing experience, rather than a rip of surging or squishing.

We need a protocol, maybe there is something already out there.

For example, cellular systems broadcast a maximum EIRP to clients, which is a tool we use with picocell on airplanes to safely permit cellular radio use.

Do we need a new airplane "pico" mode, more relating to allowing cellular transmissions in airplane mode only if you are a supported subscriber, while barring those not supported from trying to connect needlessly?

Phil Watson revealed another troubling aspect of Airplane Mode - awareness of the mode itself:
At least, make an app "Airplane mode" aware-- but Apple doesn't make that easy today (still illegal for Apple store apps) from a brief search. Besides, it would be incomplete if the OS didn't also implement it. So go to Apple & Google and get them to redefine it. 
Currently iOS allows you to enable apps for cellular use by app, but for Wifi assumes wide-open gate. Better would need a new OS permission, perhaps "Airplane Mode Wifi", implemented similar to cellular mode app-by-app selection. 
Another tangible rule suggestion from Phil is to limit or bar communications by any application while it is operating in the background.  He further recommends that we disable Wi-Fi and Bluetooth when engaging Airplane Mode (as is commonly done today) to protect those airplanes that are not PED Tolerant.  A discussion among airlines may offer some guidance on this latter concern.

Brian Johnson from United Airline described an Airplane Mode 2.0 that allows a network command to pause or mute the device during passenger address.  This feature is mandatory for IFE.  Streaming content is typically cached, so simply stopping the stream from the head-end server does not stop each client at the same time.

I appeal to whatever committee is out there providing guidelines for airplane mode. If none, perhaps APEX should step forward - they have the breadth of expertise and knowledge. At least, can the app designers think about incorporating these features?

Airplane Mode 2015 would free up considerable bandwidth while offering everyone a more reliable experience.

Peter Lemme

Copyright 2015
All Rights Reserved.


The breakthrough to compatibility is a process that demonstrates the airplane systems are PED tolerant as outlined in RTCA DO-307.

Here is an excerpt from

The methodologies are quite significant, for they become the mitigation against presenting misleading information to the flight crew.   Loss of function (or denial of service) is far less a concern than presenting data that appears to be valid, but is erroneous.  

The ARC report focused very much on the (front-door and back-door) radio frequency coupling between PED emissions and radio system receivers.  Front-door refers to creating a usable signal "in-band".  Back-door refers to creating strong emissions "out of band".   Hazardously misleading information would normally be a front-door failure mode.

The failure of display units resulting in hazardously misleading data is the most troubling of all effects.  PED tolerant testing includes type-specific testing of display units as a means to reveal any interactions. 

My personal experience in analyzing unintentional interference to glide slope or localizer, with respect to creating both carrier and required modulations such that a valid and usable signal could be created, was that it is not feasible.  However, the ARC concluded hazardously misleading data is possible.  Keep in mind this is referring to accidental interference, not malicious interference (as in "Die Hard 2").

The following failure analysis is another excerpt form the ARC report, regarding mitigation of CATASTROPHIC hazard.  

The only mitigation is prevention of the failure.  
Option 1 mitigation says the precision landing receivers are sufficiently immune from interference.   
Option 2 trusts the passengers and relies on their compliance completely.  My opinion, this option is not practical, certainly with regard to catastrophic failure modes. 
Option 3 avoids the operation all together.

A human being operates at about and 1.0E-3 failure per action.  A combination of humans would operate at some higher collective failure rate.  

From the ARC report:
Despite the fact that more passengers are bringing PEDs on board their flights, the incidence of devices accidentally being left on during the times they should be powered completely down has remained stable over the past decade.  
In 2003, 29% of travelers who owned a cell phone or wireless pager reported they had accidentally left the device turned on during a flight.  
Comparatively, in 2013, 30% of passengers reported they had accidentally left a PED (not limited specifically to cell phones or wireless pagers) turned on while in-flight. 
It is reasonable to assume at least one cellular device is fully active on every commercial flight due both to human error and arrogance.

Peter Lemme

Copyright 2015
All Rights Reserved.