In my business we make (among much stuff) a box which is very close to the required function i.e. receiving a text message in a specific format, optionally with a password etc, and operating a relay, and with various termination options. Also there is SMS confirmation of the message receipt.
The software is nontrivial (to make it work with various SIM cards etc) and was developed over a number of years, for an industrial system monitoring product which can generate a multitude of different alarms, notified by sms, email and – wait for it – fax! Modding it for a simple function like this would be easy.
The product has features which ensure that a PAYG SIM card does not expire – most today get killed after 90 days – by sending out a message say every 89 days, which means the SIM card balance goes down by only ~ 10p every 89 days, so the running cost and ongoing administration of the SIM account is nil. £50 in the SIM card should last 121 years.
It occurred to me that this could be repackaged into a “PCL box” by doing some software mods and putting it into a sturdy IP68 sealed case, with a heavy relay for switching the lights. I would think the end user cost would be a few hundred quid or € and most of that would be due to the pricey high quality box and such – not really the electronics. You will in any case spend a load more on the lights.
I’d be interested in any input regarding any special features people might want.
PCL is currently not legal in the UK if the airfield is licensed.
But even for an unlicensed airfield there is a “fear” (propagated via the forums, largely, but based on the opinion of a chap in the CAA who has retired some years ago) that the radio frequency assigned to an airfield cannot be used for anything other than voice. SMS sidesteps this (real or imagined) problem and works generally well below 2000ft.
This is a commercial posting but we allow those if the poster participates usefully in the forum, and there are already loads of people on EuroGA doing that 
Peter,
Nice idea for sidestepping the red tape, but I would hate to fiddle around with my phone at 1500 ft, trying to pick up a signal. Doesn’t sound very safe to me, and with my luck, the lights would go out on short final again, which means getting the phone out once more.
Have no-one tested the grey zone on this? I would like to see PCL installed much more widely and can find many saftely based reasons for doing so – even if the installment is not widely advertised. Alternatively, drop the licence !
In general, what happens is that you press the Send button on the SMS and the phone will keep retrying for a bit.
It is unfortunately true that modern phones are hard-coded to drop the message after several aborted retries, but usually there is a signal at those levels.
There is a simple solution to this anyway which is to use an old phone, or a Nokia phone with hacked firmware which just keeps retrying every 3 mins; I use that successfully even at FL150 or so.
The advantage of SMS is that it can be tamper-proof. VHF triggered lights can be triggered by anybody who knows the frequency, which is everybody.
The application of SMS controlled PCL would really be at a relatively private strip, not at an airfield used by hundreds of people all the time.
I would guess that turning the lights off ought to need another SMS, otherwise they might go off (if on a timer) at a bad moment.
Many licensed airfields usually want to stay licensed for a variety of reasons e.g.
As far as I am aware, there is no guarantee on the delivery time of e-mail. 99,99% of the time, e-mail arrives within seconds, but that is only due to commercial pressure and competition. I have professionally managed many e-mail servers, but have never been asked to discuss (far worse: subscribe!) any SLA on them – there must be a reason for that. I daresay the same applies to SMS. So it’s no good for the runway lights to go on only after you landed – after your plane somehow touched terra firma, actually.
I suspect that once the novelty of pcl wears off we won’t have vast problems with people clicking the lights on for the fun of it.
Its been a long time since I last fly in the states but I don’t recall them ever having any problems with iy
I second Jan’s concerns – many a time have I observed e-mail messages and SMS being delayed by hours.
On a different note: in any event, developing such a device will require some additional investment. I wonder if this investment would buy enough lawyers’ and lobbyists’ time to have the PCL prohibition struck down as a piece of regulation that serves no useful purpose and has an overall negative effect.
I think we just need proper PCL on the VHF.
One extra issue in the UK is the frequency tax. The cost for a VHF frequency is a few k a year – or will be (I am not sure if the scheme has started). You thus won’t want to have a VHF frequency allocated to a small strip type facility.
People will either use something illegal (perhaps be clicking on an unallocated frequency, having done a bit of due diligence to make sure it isn’t used nearby) or use SMS.
Or they will use another type of radio link, for which there are numerous candidates (of the garage door opener style but with a lot more power – check out the model aeroplane options, including the illegal power-enhanced ones), with all of them “technically illegal” because they breach their use license, but you will never get caught if you use it discreetly.
I have occasionally imagined having a private strip with an ILS which can be turned on as PCL – you could probably pick up the gear on Ebay. The problem with that sort of radiation is that you might kill somebody heading for a nearby airport if the stuff goes off the frequency…
I would not seriously suggest using email, due to the DHCP etc overhead causing it to require a data connection for far longer than it takes to send a text message. But paradoxically the delays which emails suffer are usually due to spam filtering at the receiving end. If you disable that, or whitelist the sender, you can eliminate that. The problem is that most people don’t have much (or any) control over this process.
In general I think you should never be commited to land on a PCL strip. If you have a big airport as a realistic alternate, I think SMS will work ok. But is this market really this big? How many people have lights on private strips used by a few pilots?
If you choose the GSM provider properly the SMS will usually come in very fast. Sending the SMS from the aircraft will depend on the location but as this will be done close to the strip you can try if it works during daytime. If you want to switch on your light from FL200 you can still buy a satellite solution.
I have occasionally imagined having a private strip with an ILS which can be turned on as PCL – you could probably pick up the gear on Ebay.
Who would have thunk it – there is one on eBay indeed.
