Tech log: EC & ADS-B

What is elec­tronic con­spicu­ity, how does it work and what air­craft equip­ment is avail­able? – Part one in a new se­ries

Pilot - - CONTENTS - Words: Philip White­man

See - Be seen - Avoid: Elec­tronic con­spicu­ity can help, but how does it all work?

In April this year the UK Civil Avi­a­tion Au­thor­ity pub­lished a new edi­tion of CAP1391 Elec­tronic Con­spicu­ity De­vices, set­ting out the ‘key out­comes’ of the Caa-led project to de­velop a new in­dus­try stan­dard for a low-cost elec­tronic con­spicu­ity de­vice for use on light air­craft.

But what ex­actly is ‘elec­tronic con­spicu­ity’? By the CAA’S def­i­ni­tion, ‘Elec­tronic Con­spicu­ity (EC) is an um­brella term for a range of tech­nolo­gies that can help airspace users to be more aware of other air­craft in the same airspace. It in­cludes transpon­ders and ra­dios’.

More ad­vanced de­vices can also trans­mit and re­ceive, dis­play­ing and alert­ing pi­lots to other/con­flict­ing traf­fic equipped with in­ter-op­er­a­ble EC de­vices. Such com­plete EC de­vices turn the tra­di­tional ‘see and avoid’ con­cept into ‘see, be seen, and avoid.’

The spe­cific low-cost EC de­vice de­fined in CAP1391 is in­tended for vol­un­tary car­riage, note, on ‘reg­is­tered and non­reg­is­tered’ UK An­nex II air­craft, non-com­plex EASA air­craft of less than 5,700kg max­i­mum take­off weight, and for glid­ers and bal­loons (in­clud­ing those cov­ered un­der ELA 1 and ELA 2) within un­con­trolled UK airspace.

While this class of equip­ment is de­signed to en­hance a pi­lot’s aware­ness of other air­craft when fly­ing in Class G airspace, it does have dis­tinct lim­i­ta­tions. A CAP1391 EC de­vice will not meet stan­dards re­quired for op­er­a­tion in con­trolled airspace and, if you have a transpon­der in your air­craft, you will have to turn off the trans­mit func­tion of the EC de­vice to pre­vent in­ter­fer­ence.

Based on ADS-B ES tech­nol­ogy

An early de­ci­sion of the EC work­ing group was that the stan­dard would be based on ADS-B ‘ex­tended squit­ter’ (ES) tech­nol­ogy which, the work­ing group con­cluded, ‘pro­vides more use­ful in­for­ma­tion to other airspace users than other so­lu­tions, while of­fer­ing low cost and low power con­sump­tion.’

So what is ADS-B and that rather cu­ri­ously named ex­tended squit­ter? Au­to­matic De­pen­dant Surveil­lance Broad­cast, to use its full name, is a ra­dio-fre­quency sys­tem that uses ei­ther a Mode S transpon­der or an in­de­pen­dent trans­mit­ter, typ­i­cally com­bined with a GPS re­ceiver, to trans­mit po­si­tional in­for­ma­tion to ATC and also other air­craft with ‘ADS-B In’ sys­tems.

The ex­tended squit­ter is in ef­fect an ex­tended por­tion of a transpon­der’s trans­mis­sion band­width that con­tains a ‘data packet’ of ADS-B in­for­ma­tion. This data packet holds iden­ti­fy­ing in­for­ma­tion about an air­craft, its po­si­tion and speed, and other data in an un­en­crypted form.

The ICAO in­ter­na­tional stan­dard for ADS-B is 1090ES (the nu­meric part stand­ing for 1090MHZ, ‘ES’ for ex­tended squit­ter), and this has been adopted through­out the world, although the dual-fre­quency sys­tem lim­ited to the USA also uses 978MHZ for op­er­a­tions be­low 18,000ft.

Note that while the CAP1391 spec­i­fi­ca­tion for EC de­vices is based on 1090ES, it re­moves the transpon­der func­tion­al­ity which replies to in­ter­ro­ga­tions by ATC radar and TCAS sys­tems. What re­mains is a trans­ceiver ca­pa­bil­ity that out­puts the air­craft po­si­tion at a set rate of once per sec­ond. This re­duces spec­trum con­ges­tion, al­lows for re­duc­tion in out­put power and al­lows the cost to be low­ered.

What equip­ment is avail­able?

While there are a num­ber of EC sys­tems on the mar­ket, only a hand­ful of prod­ucts from two man­u­fac­tur­ers meet the re­quire­ments of CAP1391. At the time of writ­ing, for­mal dec­la­ra­tions of ca­pa­bil­ity and con­for­mance to the CAA (see ‘CAA guid­ance on de­vices for elec­tronic iden­ti­fi­ca­tion of light air­craft’ link, also on www.pi­lotweb.aero) have been made by f.u.n.k.e. Avion­ics Gmbh for the PNLMGE71.STP, and uavionix for three prod­ucts, of which Skye­cho is the lat­est and most ca­pa­ble.

Priced at just over £400, Skye­cho is a por­ta­ble unit with a 25W trans­mit­ter. Traf­fic in­for­ma­tion is trans­mit­ted to any Gdl90-com­pat­i­ble EFB (elec­tronic flight bag− an elec­tronic in­for­ma­tion man­age­ment de­vice) or EFIS (elec­tronic flight in­for­ma­tion sys­tem) via its Wi-fi link. (One fur­ther bit of jar­gon busting: GDL90 is a com­mon in­ter­face for­mat.)

The Skye­cho’s in­te­grated recharge­able bat­tery is claimed to have the ca­pac­ity for a min­i­mum six hours of flight time with the trans­mit func­tion en­abled, and uavionix says that you may be able to ‘see’ air­craft with high-power transpon­ders (i.e. air­lin­ers) up to 150nm away.

In­tro­duced over a decade ago and us­ing its own 868MHZ fre­quency, the orig­i­nal Clas­sic FLARM col­li­sion avoid­ance sys­tem has saved the lives of nu­mer­ous glider pi­lots. To­day, many aero­planes, he­li­copters, low fly­ing jet air­craft and even drones carry FLARM, which has be­come the most widely used tech­nol­ogy in airspace be­low FL100. Air­craft with a FLARM sys­tem broad­cast their Gps-based pro­jected flight path (3D po­si­tions and time) to all other Flarm-equipped air­craft. The pro­jected flight paths of prox­i­mate air­craft are then com­pared, and when an im­mi­nent col­li­sion is de­tected a col­li­sion warn­ing (au­ral and vis­ual) is is­sued, to­gether with the rel­a­tive bear­ing and alti­tude dif­fer­ence of the ‘in­truder’ In­tro­duced more re­cently, POWERFLARM of­fers sig­nif­i­cantly in­creased range, ra­dio per­for­mance im­prove­ments and an in­te­grated ADS-B and transpon­der re­ceiver. POWERFLARM is fully in­ter-op­er­a­ble with all FLARM sys­tems and will also re­ceive data from all ‘ADS-B Out’ and transpon­der equipped air­craft, in­clud­ing CAP1391 EC de­vices. These air­craft are in­cluded in the smart tra­jec­tory pre­dic­tion and col­li­sion warn­ing al­go­rithms. (Fil­ter­ing the data to iden­tify and warn about the threats is a crit­i­cal as­pect of how well any EC de­vice or sys­tem per­forms and we shall be look­ing at this in the next ar­ti­cle in the se­ries− ed.)

POWERFLARM has also been se­lected by the RAF for fit­ment to its air­craft, in­clud­ing the Tu­cano fleet, run­ning over 350 units. It is ap­proved by EASA for in­stal­la­tion in both VFR and IFR (transpon­der equipped) air­craft, but por­ta­ble de­vices are also avail­able. POWERFLARM de­vices for in­stal­la­tion start at £800 and por­ta­ble vari­ants with an in­te­grated dis­play start at £1,300.

Fil­ter­ing the data is a crit­i­cal as­pect...

More af­ford­able and be­com­ing in­creas­ingly pop­u­lar in the last cou­ple of years, Pilotaware, in its lat­est Rosetta form, costs £250, in­clud­ing the first year’s li­cence. Com­pat­i­ble with ADS-B In, Rosetta is suit­able for light air­craft, LAA Per­mit types, mi­cro­lights, hang glid­ers, paraglid­ers and EASA air­craft in its ‘carry on equip­ment’ for­mat. Pilotaware can be con­nected to a num­ber of dif­fer­ent nav­i­ga­tion pack­ages, in­clud­ing Air­mate, Air­nav­i­ga­tion­pro, EASYVFR, Run­wayhd and Sky­de­mon, where other air­craft trans­mit­ting a GPS co-or­di­nate are rep­re­sented on the mov­ing map dis­play as lit­tle aero­plane sym­bols. Pilotaware also pro­vides voice alerts and an in­ter­nal RADAR screen so that ex­ter­nal nav­i­ga­tion pack­ages are not re­quired. Pilotaware claims to see more air­craft types than any other EC equip­ment, es­pe­cially when in range of an OGN-R re­broad­cast an­tenna of which there will soon be 100 across the coun­try. All that is re­quired in ad­di­tion to one’s ex­ist­ing smart­phone or tablet and the Rosetta unit is a suit­able 5.2V 2.1A USB power sup­ply.

An ‘af­ford­able light­weight and prac­ti­cal’ GPS po­si­tion source that turns the com­pany’s pop­u­lar transpon­der into an ADS-B Out de­vice, Trig’s com­pact TN72 GPS re­ceiver costs around £350. Meet­ing the po­si­tion re­quire­ments of FAR 91.227, it is al­ready be­ing used in Light Sport and Ex­per­i­men­tal air­craft in the USA to meet the 2020 ADS-B Out man­date. The TN72 will make your air­craft vis­i­ble to all ADS-B In equipped air­craft with­out, of course, in­ter­fer­ing with transpon­der func­tion as a CAP1391 EC de­vice does.

Garmin’s GDL 50R Re­moteMount ADS-B Re­ceiver, avail­able for around £740 in­clud­ing VAT, is a re­mote-mount de­vice ca­pa­ble of re­ceiv­ing ADS-B traf­fic in­for­ma­tion, GPS and air­craft at­ti­tude in­for­ma­tion for dis­play on se­lected porta­bles and mo­bile de­vices. Fea­tures such as Tar­get­trend (which is claimed to pro­vide pi­lots with a more in­tu­itive method of judg­ing tar­get tra­jec­to­ries and clo­sure rates, par­tic­u­larly in airspace with high vol­umes of traf­fic) and Ter­minal­traf­fic (which shows Ads-b-equipped air­craft and ground ve­hi­cles) fur­ther en­hance the ADS-B traf­fic pic­ture and are unique to Garmin prod­ucts. Wire­less and hard­wired com­pat­i­bil­ity of the GDL 50R in­cludes G3X Touch glass flight dis­plays, aera 660 and aera 795/796 avi­a­tion porta­bles, as well as wire­less con­nec­tiv­ity with the Garmin Pi­lot app on Ap­ple and An­droid mo­bile de­vices.

The mes­sage to take home here is that while a given EC de­vice or sys­tem may de­tect other air­craft, de­pend­ing on the tech­nol­ogy, it may or may not make it­self ‘vis­i­ble’ to them. It pays to check the spec­i­fi­ca­tion care­fully be­fore buy­ing!

ABOVE: uavionix's Skye­cho is one of the few units that com­ply with the CAA’S CAP1391 spec­i­fi­ca­tion for low-cost EC de­vices

BE­LOW: POWERFLARM unit, dis­play high­light­ing an air­craft de­tected on a col­li­sion course

ABOVE: Skye­cho dis­play on Sky­de­monBE­LOW: Garmin GDL 50 unit with dis­plays show­ing traf­fic on Garmin por­ta­ble and tablet

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