The PAPI simulator is supposed to be a cutting edge bit of kit which has been developed by City University and by all accounts it has been accepted by the UK CAA and the FAA. They're now waiting for City Uni to release it for actual use.
Regarding light signals, this has been one area that I have looked at in my study and I feel it to be of very little, if any, consequence whatsoever to modern aviation. I will precis my findings below:
Firstly, the vast majority of aricraft these days have Comms equipment and thankfully the failure rate is very low (although I have personally experienced radio faiure twice).
An aircraft may not enter an ATZ without permission from ATC. The ATZ, at a minimum is 2 nm in diameter. I have used these lights in flight in daylight and they are (a) very small, (b) not that bright and (c) extremely difficult to discern from even 1 nm away, regardless of colour, even when you know where to look for them, therefore, seeing them from 2 - 2.5 nm away (i.e. outside the ATZ) in daylight is extremely difficult, if not impossible. At night, applying the same rules regarding entering the ATZ, when you would think that the light would be easier to see, in fact it gets lost from 2 - 2.5 nm away amongst (a) light pollution, (b) airport lights and (c) lights from other surrounding buildings and streets.
If an aerodrome does not have ATC and the issue of ATZ entry, circuit joining and landing is down to pilot discretion, of what consequence are light signals? None, apart form indicating to the aircraft that it may not land, for some reason. There are far easier and more identifiable ways of achieving this than firing coloured lights, e.g. placing a big 'X' or even a vehicle on the runway. Before anyone questions what would happen if the pilot didn't see the vehicle (a) what is the pilot doing operating an aircraft in the first place if he can't see a vehicle on the runway and (b) in that case, what guarantees are there that the pilot will see coloured light signals?
Regarding operation of signal guns in the cockpit, if operation of a mobile phone is considered a road safety hazard how can operation of a cumbersome signal gun not be considered a flight safety hazard? Also, it is not a legal requirement to carry coloured signal guns in the cockpit and I personally have never heard of anyone carrying such an instrument. Lastly, if a signal gun of sufficient luminance (to enable it to be seen from the ground) was carried and operated inside the cockpit, the light reflection off the inside of the cockpit perspex would in all probability cause serious impairment to the pilot's adapted night vision, thereby rendering any attempt at landing or continuing to fly extremely hazardous. Therefore, it is my contention that the use of colour signal guns from a closed cockpit should be banned as a flight safety risk.
Lastly, the many variations in colour controlled signals could be replaced by signals that are easier to identify and which mean the same on the ground as in the air. Get rid of all the variations and replace them with 3 different speed / duration flashing (easier to see than colours) lights that translate into GO/CONTINUE, STOP/WAIT, RETURN TO APRON/GO AWAY, e.g. Slow - long pulses for the first one, Medium - medium pulses for the middle one and Rapid - short pulses for the latter, similar to Marker Beacons. Use colours as well to aid the identification process but do not rely on one method of identification only.
I await constructive comments and debate eagerly, particularly those that will help develop the argument.
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