Re: [Drip] ADSB

[Robert Moskowitz <[e-mail]>]

On 7/12/23 11:13, Alexandre Petrescu wrote:
> thanks for the clarification
> I must have endeavoured in unchartered lands...
>
> Just to clarify: I am not disputing.
>
> I came with this thread to say that I saw ADS-B drones on flightradar.

I am sure people do it.  How they get an aircraft number might be 
interesting.  Of course some transponders are preset for this from what 
I have heard.

Also I am away of code that takes "standard" Remote ID messages and 
feeds that into ADS-B systems.  So you see them in things like 
FlightAware, but they are NOT sending ADS-B.

of course you have to lie about the aircraft number, going from the 20 
character UA ID to the 24-bit aircraft number...

The one effort I reviewed on this I asked this question, and they said 
the hashed the UA ID down to 24 bits...

>
> That's about it.
>
> Alex
>
> Le 12/07/2023 à 16:56, Stu Card a écrit :
>> The UAS RID rules are _not_ defined in this WG!
>>
>> They are defined by Civil Aviation Authorities (CAAs) in each 
>> jurisdiction, with coordination via the International Civil Aviation 
>> Organization (ICAO).
>>
>> Disputing the rules should be taken up with them, not with the DRIP 
>> WG or any part of IETF.
>>
>> Such rules are mentioned in DRIP docs only as background: motivation, 
>> context & constraints.
>>
>> Standard Means of Compliance with UAS RID rules, in turn, is mostly 
>> the province of SDOs other than IETF, primarily ASTM International. 
>> Again, disputing those standards should be taken up with those SDOs, 
>> not us.
>>
>> Only if some reference, in DRIP docs, to the rules or external 
>> standards, is factually incorrect or unclear in expression for 
>> understanding by DRIP protocol implementors, is it something we 
>> should be debating here.
>>
>>
>> Get Outlook for Android <https://aka.ms/AAb9ysg>
>>
>> ------------------------------------------------------------------------
>> *From:* Alexandre Petrescu <[e-mail]>
>> *Sent:* Wednesday, July 12, 2023, 10:43
>> *To:* Stu Card <[e-mail]>; Robert Moskowitz 
>> <[e-mail]>; Carsten Bormann <[e-mail]>
>> *Cc:* [e-mail] <[e-mail]>
>> *Subject:* Re: [Drip] ADSB
>>
>>
>>
>> Le 12/07/2023 à 16:00, Stu Card a écrit :
>>> Very short answers (all for which I have time):
>>>
>>> The rules for RID are based not primarily on RF considerations, but 
>>> on aviation considerations.
>>
>> hmmm... it's a principle that is reasonable and that could be debated.
>>
>> One will excuse me for not knowing precisely what are the RID rules.
>> The RID rules are defined in this WG and I will need to look at them.
>>
>> If I look at them, one day, I will look at them from this perspective:
>>
>> For example, when RID rules say 'altitude' they should say 'altitude
>> expressed in meters and not in feet as is currently the inherited case
>> from WWII development of aviation'.
>>
>> This kind of text could be of enormous help to implementers: they simply
>> would need to call less functions(), because less need of conversions.
>>
>> It is the same when RID rules say 'heading' or 'speed', or when we talk
>> about airport track orientation.  It should be made easy to implementer
>> to compare a heading value in a 'heading' of a UAS to that of a track.
>> One should come up with a single common way of expressing track
>> orientation, compatible to that of RID rules, instead of several and
>> incompatible, as is the case in current air flight industry.  It is
>> because if one does that (interoperable defs of headings) then the
>> programmer has an easier task.
>>
>> Also, about RID rules: they should say that when ASTM wants to send
>> position and heading they should send the NMEA statements, without
>> conversion.
>>
>> Until then, if we can not do that, we can also have a human listening to
>> the radio airport and maneouvering locally or from a distance, using an
>> innombrable number of calculators and conversions, after having learned
>> tomes of manuals about how to fly things.  It is basically easier.
>>
>>>
>>> Crewed aircraft _mostly_ fly above 500 feet, except during takeoff 
>>> and landing.
>>
>> I always had problems with this term 'crewed' aircraft.  I noticed it
>> also in the TVR WG, in its reverse form 'uncrewed' aircraft.
>>
>> But in reality there can be uncrewed crewed aircrafts too (Unmanned Air
>> Mobility device, a flying taxi, does carry a couple of persons on board
>> - 'crew?', yet none of them actually drives the UAM - they just signed
>> the insurance agreement).  An uncrewed aircraft is still crewed by the
>> fact that a (group of) persons on the ground is its crew (drone Reaper
>> is such).  There can also be these devices that are not crewed, are not
>> continuously driven from a ground by a crew, yet there are very many
>> eyes of people loooking at where it is going to - they're
>> pre-programmed.  These would be the true 'uncrew' aircraft even though
>> there are many crews simply looking at them.  They fly at more altitudes
>> than 500 feet.
>>
>> This is why I am not sure how to use this term 'crewed aircraft'.
>>
>> But I think you meant a 200 passenger aircraft like a regular airline
>> flight from a city to another.  Even that can be automated 
>> (crewless?) soon.
>>
>>> Small uncrewed aircraft _mostly_ fly at much lower altitudes, as 
>>> they are flown largely not to get from one place to another, but for 
>>> photographing or otherwise sensing things on the ground (or for 
>>> recreation).
>>
>> BEcause of this term 'crew' I can not say whether I agree or not with 
>> you.
>>
>> Instinctively, I'd say that there are so many other flying aircraft that
>> it is hard to say so easily at which altitudes are they allowed or not,
>> simply based on that 'crewed' qualifier.
>>
>> I think the point of view of 'crewed' vs 'uncrewed' is limited in
>> itself, leading to potentially missing some aspects.
>>
>>> The FAA has established an upper limit
>>> of 400 feet AGL for small uncrewed aircraft flying under their rule 
>>> appropriate for most such, to provide 100 feet of vertical
>>> separation from these small UAS and where the crewed aircraft
>>> _mostly_ fly.
>>
>> I will not oppose - maybe it is sufficient for them.
>>
>> If I were to be picky, I'd say that the notion of 'AGL' itself can be
>> subject to debate (there are several sea levels in this world and
>> moreover they change as we speak) and if one asks why then I reply that
>> if one would like to put NMEA statements in ASTM messages for the goal
>> of avoiding conversions then one might be facing such aspects of
>> precisely what is a sea level.
>>
>> But I will not go to the respective SDO, so I leave it there.  I agree
>> they set limits where they need them.
>>
>>> WRT units: yes it is a mess; no the EU does not use precisely the 
>>> metric equivalents of feet etc. in their rules; note my original 
>>> message said "EU rules are similar" not "EU rules are the same
>>> except for translation of metric units".
>>
>> I agree, you did not say that.
>>
>>> IETF does not get to write rules for aviation, therefore neither
>>> does IETF get to write rules for aviation communications; we can
>>> only provide technical standards for interoperable network protocols
>>> that _enhance_ those communications.
>>
>> It's a good thing, because enhancing communications is always good.
>>
>> Alex
>>
>>>
>>> -----Original Message----- From: Alexandre Petrescu 
>>> <[e-mail]> Sent: Wednesday, July 12, 2023 9:45 AM
>>> To: Robert Moskowitz <[e-mail]>; Carsten Bormann 
>>> <[e-mail]> Cc: Stu Card <[e-mail]>; 
>>> [e-mail] Subject: Re: [Drip] ADSB
>>>
>>>
>>>
>>> Le 12/07/2023 à 13:56, Robert Moskowitz a écrit :
>>>>
>>>>
>>>> On 7/12/23 06:45, Carsten Bormann wrote:
>>>>> On 2023-07-12, at 11:52, Alexandre Petrescu 
>>>>> <[e-mail]> wrote:
>>>>>> why not 400m
>>>>> This is not a domain where we get to invent boundaries.
>>>>>
>>>>> (Also, generally speaking, of course we should have a strong
>>>>> bias to using SI units, but in a domain where regulation is
>>>>> widely based on furlongs per fortnight, we’ll have to adapt.)
>>>>
>>>> And anyway it would be 125M to be a bit more than the Imperial 400'.
>>>
>>> True.
>>>
>>> And it obviously begs the question whether in Europe they also have 
>>> the same limit of 400' equivalent in meters.  I strongly doubt that 
>>> an EU document would talk about a limit of precisely 121.92 meters 
>>> just because of being converted to the easy to grasp 400 feet.
>>>
>>> At that point we talk about devices that might be different in an EU 
>>> market than in an US market.
>>>
>>> What is the EU altitude limit for numerous drone aircraft to be 
>>> considered flying very low, so numerous and so low such as to be 
>>> forbidden to carry ADS-B equipment (or turn it off at lower than
>>> that altitude if it carries one)?
>>>
>>>> Why 400'?
>>>>
>>>> I think it was to keep general aviation some reasonable distance 
>>>> above people on the ground.  As the ceiling for UA that is a 
>>>> consequence.
>>>
>>> You see, I think there is an error.
>>>
>>> 400 feet might be a good limit in terms of separation of people and 
>>> objects above their heads, but it is certainly not any limit in
>>> terms of radio communication.
>>>
>>> If there is to be a radio communication limit (use or not use ADS-B) 
>>> it should be based on the power levels it uses and the guarantees of 
>>> range. In WiFi, bluetooth and 2G..5G that's how they separate.
>>>
>>> For example, an 5G-carrying UAS would be limited to 450meter
>>> altitude because that is how high the ground 5G oriented towards
>>> ground reaches high.
>>>
>>> A bluetooth-carrying UAS (and not carrying ADS-B) would be limited to
>>> 100 meter altitude because that is how high a bluetooth device is 
>>> allowed to emit, by bluetooth regulation.
>>>
>>>> "They can't go any lower, you can't go any higher."
>>>
>>> Strange.  Many devices, especially those who plane or glide like 
>>> these UAS drones, and helicopters too, will stay stable at very many 
>>> low altitudes.  Their power systems - more and more performing, 
>>> allows for that.
>>>
>>> I very well see a helicopter stable 100meter above the ground, and 
>>> surely it carries an ADS-B device, if not several of them.
>>>
>>>>
>>>> It is called boundaries to keep unequal players apart.
>>>>
>>>> One of the interesting debates in this is that the 400' floor is to
>>>> ground obstacles like radio towers.  Thus since big birds have to
>>>> stay 400' from that 700' radio tower down the block, you can take
>>>> your UA up to 1100' right next to it...  Or so some claim.
>>>
>>> Right!
>>>
>>> RAdio towers, or radio towers with even higher anti-flash 
>>> ('paratonnerre', fr.) on them?  That adds some 10 meter to the 
>>> picture, to which an UAS drone would need to pay attention, just
>>> like helicopters need to care about power lines above ground too.
>>>
>>>>
>>>> And speaking of Imperial vs Metric...
>>>>
>>>> Civil aviation separation is 1000'.
>>>>
>>>> This has already caused incidents where a lesser  Metric distance 
>>>> was used by one aircraft against one using the greater separation 
>>>> of Imperial.
>>>>
>>>> Fun!
>>>>
>>>> Not.
>>>
>>> I agree.
>>>
>>> Alex
>>>
>>>>
>>>> Bob
>>>>
>>
>

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