Karena penanya tidak menyebutkan apakah upacara benderanya dalam hal pengibaran atau penurunan, maka saya berikan alternatif:

flag hoisting/lowering ceremony (upacara pengibaran/penurunan)

Petugas upacara yang dimaksud di sini bisa dipadankan dengan ceremony officer dalam peringatan ulang tahun kemerdekaan RI.

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Note added at 14 menit (2017-04-12 03:53:15 GMT)
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Referensi : http://www.expat.or.id/info/august17th-IndonesianIndependenc...

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Note added at 19 menit (2017-04-12 03:58:26 GMT)
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Karena yang dimaksud di sini bukan hanya petugas pengibar atau penurun bendera, tapi mengacu kepada semua petugas upacara, maka sebaiknya dipakai ceremony officer, sedangkan 17 agustus di sini mengacu kepada hari kemerdekaan Republik Indonesia maka dipadankan dengan Indonesia's Independence Day Celebration.

⛱ Jika tunggal: Official, jika jamak: Officials.

☕ Karena berupa rangkaian tindakan tertentu dan tetap, upacara bisa dianalogikan dengan pertandingan olahraga (ada pembukaan/kick-off dan ada peluit / bel penutup). Akibatnya, istilah petugas di sini pun bisa meniru: match offiicals ==> ceremony officials.

☕ Untuk 17 Agustus, boleh kita coba meniru AS yang sering menggunakan sekadar 4th of July dalam nama berbagai acara pengenangan/komemorasi kemerdekaannya (mis. 4th of July Potluck / Parade / Fireworks,... lihat surjaya ke-4, tahun ini mereka sudah rencanakan dari sekarang!!).

⛱ Hasilnya adalah: 17th of August Flag Ceremony kalau upacara bendera, atau 17th of August Commemoration Ceremony kalau upacara jenis lainnya.

★彡 SURJAYA
https://www.italki.com/question/143694
Officer vs Official... What's the difference between them?...
Technically, the words are synonyms for each other, but in common speech they are used in specific ways that you learn by experience. e.g. chief executive officer rather than chief executive official, or sports officials rather than sports officers...

http://www.fifa.com/worldcup/news/y=2017/m=3/news=match-offi...
The FIFA Disciplinary Committee has decided to ban the Ghanaian match official Joseph Odartei Lamptey from taking part...

http://www.foxnews.com/story/2008/08/12/official-child-singe...
A 7-year-old Chinese girl was not good-looking enough for the Olympics opening ceremony, so another little girl with a pixie smile lip-synced "Ode to the Motherland," a ceremony official said — the latest example of the lengths Beijing took for a perfect start to the Summer Games.

http://www.catonsvillecelebrations.org/parade-rules/
We are applying to participate in the Catonsville 4th of July Parade on Tuesday, July 4, 2017 .. We agree to be in our assigned position in the formation area at the time instructed and to follow the instructions of parade officials.