For sure it is safer to fly an Hewa Bora 727 rather than a Vickers Viscount or AN-8, you will feel safer, but try to take-off from Goma or Mbuji-Mai with 2000 meters runway at elevation and hot temperature in a fully laden HBA 727 with JT8D-9 engines, you will realise that the earth is indeed round and that's why these machines fly. Sometimes, it is not round enough, UTA made this experience in Cotonou lately.
The ICAO non compliance is in fact related that the Congolese CAA has been found non-compliant by the FAA, thus it disqualisfies all Congolese operator.