Glofish, many years ago similar incidents occurred in the same airspace as where this event happened. It always occurred because the aircraft at top of descent was at the limit of VHF range. Sometimes what they thought they heard was not what was said. When being the departing aircraft I caught the error in the clearance, and asked ATC to confirm it. ATC never seemed to catch it, perhaps the same issue? Anyhow, a new procedure was introduced then that the departing aircraft would be given a radial to fly to his right of the airway, and the arriving aircraft kept on the airway (best not confuse due to poor radio right?). This gave both lateral and vertical separation. Worked a treat. But now the wheel has turned.
We can complain about ATC as they did not check the clearance read back by the crew. The air Seychelles Crew heard the wrong readback and said nothing. Who knows how much of the traffic information they heard. Perhaps only the lower when passing bit? Dunno as I wasn't there. But I do know this Crew and the air Seychelles Crew has flown around the world a few times before this and I haven't been reading about them before. It would seem the EK Crew flew the clearance they believed was theirs. TCAS wise the air Seychelles Crew had more warning as they were expecting the Ek Crew to stop at 380, the Ek Crew would have only noticed the other aircraft still climbing after they had already leveled (air Seychelles reported at 359 right?). Remember airbus TCAS can display 9000 feet above when in above (used in climb) and 9000 feet below when in below (used in descent). The 380 TCAS would have a range advantage 100nm instead of 40nm, but in this case that is mute as the climb above the expected 350 would have happened at a much closer range. The 380 was 2000 feet lower to where air Seychelles was expecting it to be. The 330 was just crossing the expected ALT at the same time.
No one is golden here. But the incident would not have happened if a tried and tested procedure was not abandoned and if ATC had done his job to correct a wrongly readback clearance. The fact it was not corrected by ATC helped confirm to the EK Crew they were flying the correct clearance. Which we armchair legends know they were not.
Last edited by donpizmeov; 25th Jul 2017 at 07:52.