App could deliver IFR clearances to mobile devices

GaryandAlice wrote:

Thanksgiving Day, it appeared all of California was traveling to family. And they were all using airplanes.

And if your aircraft did not have ADS-B Out installed, you are only seeing a minority of the traffic!

Peter wrote:

The only real “push” that exists in the mobile context is the original GSM one: a phone is constantly listening for tower signals and about every 10 mins it reports itself to the nearest tower.

Not really. A mobile device these days has an IP connection to the general Internet, and in principle IP can do true “push”, but:

1. dynamic IP address → need constant reregistration to a server to update the IP to contact. This is the same as “every 10 min it reports itself to tower”
2. NAT → need constant traffic to keep the NAT association alive. This is also comparable to “about every 10 mins it reports itself to the nearest tower”.

IPv6 is designed to make this better (no NAT, IPv6 mobility, …), but is barely being deployed “last mile”, and the least in mobile … probably because it destroys telco’s business model. They even reinvented NAT on top of IPv6.

But the last thing which the cellular networks want is VOIP working because it would open the door to the holy grail of a VOIP-only phone whose SIM is just a data SIM and no “hard” number

I’m not sure. That situation is technically already here somewhat. Here (Luxembourg), the telcos kinda already have adapted their pricing to that: the difference between different subscriptions is purely the data; nearly all subscriptions have exactly the same “fake unlimited” for calls, SMS and MMS included. The only thing they would really lose is international calls to non-EU (and non-USA) destinations, that are outside the “flat fee”.

A mobile device these days has an IP connection to the general Internet, and in principle IP can do true “push”

Regardless of any protocol, you need to be on a known IP in order to receive UDP packets.

I recently spoke to someone who is involved with this stuff. The problem is that while a phone user walking about a town on 3G/4G will keep his IP despite going into a toilet and briefly breaking the signal (so is not doing DHCP all the time, so you could just send him push notifications via UDP) this does not work when airborne. For a start, you are probably switching networks. Also you lose the signal for say 1hr at a time. And then it seems clear that some systems simply blacklist you for hopping across too many towers too fast – I see this a lot over France where I see a full signal for ages but no data (no IP allocated, apparently).

If you had a phone with a fixed IP (which is possible – we have this at work for ADSL backup, a SIM card for £3/month) then you could deliver whatever you want to an airborne user, just by throwing UDP packets at him (serially numbered, but nothing more complex). The most brief connectivity windows might be enough. The problem is that the requirement for such a phone (probably a pricey corporate-level cellular product) would make the service unmarketable (as would the need for a rooted phone).

That situation is technically already here somewhat. Here (Luxembourg), the telcos kinda already have adapted their pricing to that: the difference between different subscriptions is purely the data; nearly all subscriptions have exactly the same “fake unlimited” for calls, SMS and MMS included. The only thing they would really lose is international calls to non-EU (and non-USA) destinations, that are outside the “flat fee”.

With the EU roaming gravy train disappearing, they want the non EU traffic even more I recently got billed a huge amount (tens of €) for downloading a few k while overflying Albania and Montenegro.

And if your aircraft did not have ADS-B Out installed, you are only seeing a minority of the traffic!

That seems to be a US-specific quid pro quo, AIUI.