I see you…

But do you see me? Part two of our se­ries on elec­tronic con­spicu­ity fo­cuses on the ca­pa­bil­i­ties – and com­pat­i­bil­ity – of the ex­ist­ing tech­nol­ogy

Pilot - - Tech Log: Electronic Conspicuit­y - Words: Philip White­man Il­lus­tra­tions: FLARM

In July’s ‘Tech Log’ we looked at the CAA’S CAP1391 def­i­ni­tion of a low-cost elec­tronic con­spicu­ity de­vice for use in Class G ‘see and avoid’ airspace, and the ADS-B (Au­to­matic De­pen­dence Sur­veil­lance Broad­cast) tech­nol­ogy upon which it is based. In re­search­ing the broader range of EC (elec­tronic con­spicu­ity) de­vices and equip­ment on the mar­ket, it quickly be­came ap­par­ent that some sys­tems are in­com­pat­i­ble with oth­ers−not the least of the

prob­lems be­ing that CAP1391­com­pli­ant de­vices can­not cur­rently be op­er­ated along­side a Mode S transpon­der−and the pic­ture of which de­vice can ‘see’ which is very con­fus­ing.

His­tor­i­cally, EC de­vices have been built to dif­fer­ent stan­dards and to meet dif­fer­ent re­quire­ments. “Like Brexit, elec­tronic con­spicu­ity can mean dif­fer­ent things to dif­fer­ent folks,” ob­serves Keith Vin­ning of Pilotaware. “This is why at the re­cent EC fo­rum held in Cologne in June 2018, EASA con­cluded that as far as EC is con­cerned ‘no one size fits all’.

“Glid­ers op­er­ate in very close prox­im­ity, and when ther­malling fly in a man­ner that would un­set­tle most power pilots be­cause of the close prox­im­ity. FLARM, with its built-in pre­dic­tive col­li­sion avoid­ance al­go­rithms, was orig­i­nally de­vel­oped for [the] spe­cific needs [of the glid­ing com­mu­nity].” Transpon­ders are not manda­tory in the glid­ing world and are gen­er­ally not fit­ted due to weight, cost and power con­cerns−all driv­ers in the evo­lu­tion of FLARM which, as its man­u­fac­turer points out, is still the only true col­li­sion avoid­ance sys­tem, other EC tech­nolo­gies and de­vices sim­ply serv­ing to re­ceive and/or trans­mit po­si­tion.

Pilots fly­ing pow­ered air­craft in Class G and Class E airspace are look­ing for some form of air-toair elec­tronic con­spicu­ity that is com­men­su­rate with the speeds at which they fly and the air­craft that they are likely to en­counter. “Cost is al­ways an is­sue,” says Keith Vin­ning “and this is why Pilotaware and Power FLARM are gain­ing in pop­u­lar­ity. In the case of Pilotaware all traf­fic can be de­tected (in­clud­ing FLARM when in range of an OGN-R re-broad­cast sta­tion) and Power FLARM will de­tect and be vis­i­ble to other FLARM users and also de­tect Mode C/S and ADS-B.”

“Let’s not for­get full ADS-B in­stal­la­tions us­ing equip­ment from Avi­dyne, Garmin and Trig in GA, all the way up to Air­bus and Boe­ing,” says Andy Davis of Trig Avion­ics. “In a mixed traf­fic environmen­t, see­ing air­line traf­fic on your re­ceiver is part of the pic­ture and there is also a small but grow­ing in­stalled base of ADS-B equip­page in light GA. Trig and Garmin are mak­ing their US STC data avail­able in Europe so any­one who has the kit−a GNS430W and a TT32 for in­stance−can wire it up and be fully ADS-B Out ca­pa­ble.”

The rather dif­fer­ent, pri­mary elec­tronic con­spicu­ity re­quire­ment for those op­er­at­ing in Class D and above airspace is for equip­ment that will make the air­craft vis­i­ble to ATC: a Mode C or S transpon­der. “When in con­trolled airspace you are ex­actly that; un­der con­trol,” ob­serves Keith Vin­ning “and you do as you are told or bear the consequenc­es of an un­wel­come let­ter from the author­i­ties.”

In the UK ATC mon­i­tors the po­si­tion of Mode C- or S-equipped air­craft in con­trolled airspace us­ing pri­mary radar with the as­sis­tance of sec­ondary sur­veil­lance radar built into an air­craft’s transpon­der. Mode C re­sponds to an in­ter­ro­ga­tion with the air­craft’s height rel­a­tive to 1013.2mb, mak­ing the ver­ti­cal lo­ca­tion de­tec­tion ac­cu­rate−and Mode S pro­vides even more in­for­ma­tion to help iden­tify the in­di­vid­ual air­craft. Note that there are cur­rently no ADS-B ground sta­tions paint­ing on ATC screens in the UK, al­though there are tri­als and ex­per­i­ments tak­ing place.

“Pri­mary radar is very expensive to in­stall and main­tain and the ar­gu­ment goes that if ev­ery­one was to trans­mit ADS-B Out at 1090MHZ, and ATC were to re­ceive it, then the radar could be turned off,” ob­serves Keith. “This would save the author­i­ties

POW­ER­FLARM demo, the he­li­copter now veer­ing away from a col­li­sion course show­ing up on the unit mounted high in cen­tre panel

For col­li­sion avoid­ance it's not just the prox­im­ity of other air­craft that mat­ters, but the pro­jected tra­jec­tory

POW­ER­FLARM Por­ta­ble

FLARM radar dis­play on ATD’

FLARM col­li­sion warn­ing on ATD dis­play

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