Re: [Drip] ADSB

[Alexandre Petrescu <[e-mail]>]

Le 12/07/2023 à 17:05, Robert Moskowitz a écrit :
> 
> 
> On 7/12/23 10:43, Alexandre Petrescu wrote:
>> 
>> 
>> 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.
> 
> The RID rules are defined by the various Civil Aviation Authorities.
> In the WG, we are working within those constraints to make them safer
> to use.
> 
> 
>> 
>> 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'.
> 
> They assume a lot.  FAA rules on RID do not say this.  And we get
> into fun with barometric altitude or which model for earth shape???

But the RFC abour RID does say 'altitude' and that is why I said
'altitude in meters'.

Barometric altitude, Earth shape and variable sea levels are important
variables that could be taken into account if necessary.  If not
necessary then I do not dispute it elsewhere, neither here.

> 
>> 
>> This kind of text could be of enormous help to implementers: they
>> simply would need to call less functions(), because less need of
>> conversions.
> 
> 
> You would not believe (or maybe you would) the debates we had in ASTM
>  over accurately reporting altitude with consumer grade electronics.
>  Basically it is impossible.  So you go with "on average we are right
> and not reporting we are below ground level." :)

I can agree :-)  Average is what can be done when the real numbers are
too complex so to say.

[...]>> 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.
> 
> And why I don't expect autonomous flight to work on the large scale
> for quite some time.

I had a similar tendency, but recently it seems that more and more
autonomous driving takes place, and it might be that autonomous flight
might follow a similar path.  It might be that 200-passenger airplanes
might be self-driven to a large extent before year 2030.

But autonomous flight is more than that.  There are so many autonomous
devices up there, in a range of altitudes.

I am not sure how to express it: in terms of numbers, of altitudes, of
their goals, etc.

Even 'drones' and UASs and UAVs UAMs are not enough words to express
their kinds.  Even the word 'drone' is used to express so many very
different things, which have their other dedicated meanings.  And every
day new names come up for these 'drones'.

Alex

> 
>> 
>>> 
>>> 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
>>>> 
>> 
> 
> -- Standard Robert Moskowitz Owner HTT Consulting C:248-219-2059 
> F:248-968-2824 E:[e-mail]
> 
> There's no limit to what can be accomplished if it doesn't matter who
>  gets the credit