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Admiralcloudberg is, you know, never really a pick-me-up story kind of place, but this one is particularly grim. Among many other things, a reminder that softw

Admiralcloudberg is, you know, never really a pick-me-up story kind of place, but this one is particularly grim. Among many other things, a reminder that software upgrades need to be carefully planned, with an assumption that other stuff might go wrong while the system is offline.

FabHK 3y ago
What is somewhat encouraging while reading the (grim) narratives of aviation accidents is this: how much has to go wrong for things to go seriously wrong (compare James Reason's Swiss Cheese model of accidents), and how most similar cases end well. In this case, things that went wrong - and any one of them not going wrong might have averted the disaster: 1. Kids missed the original plane and had to get on this special charter flight instead. 2. Skyguide had just the previous year reduced staff from 3 to 2 controllers at night, and 2'. One of the controllers took an unofficial break. 3. There was an unexpected delayed A320 coming in, distracting the single controller. 4. The Tupolev was equipped with TCAS - if it hadn't been, TCAS on the other plane would not have issued an RA, and they might have stayed level or climbed instead of descending, as instructed by TCAS. (Though without TCAS it would not have been allowed to fly in Europe, probably.) 5. ATC happened to tell the Tupolev to descend, and TCAS happened to tell the 757 to descend. 6. That ATC instruction came exactly at the same time as the TCAS instruction on the 757, so the 757 crew didn't hear the ATC instruction to the Tupolev. 7. The Tupolev crew did not acknowledge that ATC instruction (which the 757 crew might have heard). 8. A bit later ATC repeated the instruction, and exactly at the same time TCAS on the 757 also repeated the instruction, so again they didn't hear the ATC instruction to the Tupolev. 9. Just then, the delayed A320 called ATC again, so the controller was distracted and did not monitor that his instruction to descend resolved the conflict successfully. 10. The copilot in the 757 had to go to the toilet just 18 seconds before all this happened. 11. It was night, making visual separation harder, possibly. 12. The 757 crew was trained to prioritise TCAS > ATC, the Tupolev crew was more or less trained to prioritise ATC > TCAS. 13. The Tupolev crew following ATC over TCAS received an ATC instruction that was in line with their right-of-way rules (left plane climbs, right plane descends), so it must have seemed more plausible. 14. The Tupolev crew had a first officer that suggested following TCAS instead, but he was not sitting in the RHS because there happened to be an extra Instructor Captain on that flight in the RHS who chose to follow ATC. 15. There happened to be a software upgrade at Zuerich ATC that night that disabled the Short-Term Conflict Alert light. 16. That software upgrade also disabled the phone lines, forcing the controller to waste time with the phone when trying to call Friedrichshafen for the delayed A320, and also prevented Karlsruhe ATC from warning Zuerich ATC of the problem. 17. ATC made a small, per se inconsequential, mistake of confusing "at your 2 o'clock" with "at your 10 o'clock". 18. The 757 crew waited 23 seconds to tell ATC that they were in a TCAS RA descent, by which time ATC was busy with the delayed A320. 19. The Tupolev crew was too busy/distracted to hear and understand that 757 TCAS RA descent call. 20. The ATC radar updated only every 12 seconds and did not yet reflect the 757's descent when ATC decided to instruct the Tupolev to descend. 21. The serious incident earlier in Japan with ATC/TCAS mismatch had not yet filtered through to all crews worldwide. It's just so unlikely.
- Maxion 3y ago
  You forgot the karlruhe controllers who saw it all, and tried to call but the phone lines were down. They obeyed protocol and didn’t contact the planes that weren’t in their sector,even though they could have.
  - rossdavidh 3y ago
    It's a tough call. If they had contacted them, they also could have talked over instructions from the other sector's controller, for all they knew, which is presumably the reason for the protocol? Tough decision.
  - seabass-labrax 3y ago
    I wonder whether, had they chosen to contact the aircraft outside their sector, the Skyguide controller would have heard them. With VHF radio being line of sight, the aircraft would probably have heard them, but Skyguide would be based at a ground station that was perhaps occluded by nearby mountains or other buildings. Where I live, I can't pick up a VHF ground station which is nearly in my line of sight only fifty kilometres away.
- banannaise 3y ago
  > It's just so unlikely. It's just so unlikely that this particular crash is the one that happens. A crash of this sort was all but inevitable, unless significant changes were made, and significant changes weren't going to be made until a crash of this sort happened. The article details a near-miss 17 months prior that would have killed 677 people. If this had been avoided as well, there would have been another a few months later, and another, and another, until one finally met all the conditions for an actual collision. Is it unlikely that the roulette wheel will land on 00 this time? Of course. Is it unlikely that it will ever land on 00? No!

FabHK 3y ago

What is somewhat encouraging while reading the (grim) narratives of aviation accidents is this: how much has to go wrong for things to go seriously wrong (compare James Reason's Swiss Cheese model of accidents), and how most similar cases end well. In this case, things that went wrong - and any one of them not going wrong might have averted the disaster: 1. Kids missed the original plane and had to get on this special charter flight instead. 2. Skyguide had just the previous year reduced staff from 3 to 2 controllers at night, and 2'. One of the controllers took an unofficial break. 3. There was an unexpected delayed A320 coming in, distracting the single controller. 4. The Tupolev was equipped with TCAS - if it hadn't been, TCAS on the other plane would not have issued an RA, and they might have stayed level or climbed instead of descending, as instructed by TCAS. (Though without TCAS it would not have been allowed to fly in Europe, probably.) 5. ATC happened to tell the Tupolev to descend, and TCAS happened to tell the 757 to descend. 6. That ATC instruction came exactly at the same time as the TCAS instruction on the 757, so the 757 crew didn't hear the ATC instruction to the Tupolev. 7. The Tupolev crew did not acknowledge that ATC instruction (which the 757 crew might have heard). 8. A bit later ATC repeated the instruction, and exactly at the same time TCAS on the 757 also repeated the instruction, so again they didn't hear the ATC instruction to the Tupolev. 9. Just then, the delayed A320 called ATC again, so the controller was distracted and did not monitor that his instruction to descend resolved the conflict successfully. 10. The copilot in the 757 had to go to the toilet just 18 seconds before all this happened. 11. It was night, making visual separation harder, possibly. 12. The 757 crew was trained to prioritise TCAS > ATC, the Tupolev crew was more or less trained to prioritise ATC > TCAS. 13. The Tupolev crew following ATC over TCAS received an ATC instruction that was in line with their right-of-way rules (left plane climbs, right plane descends), so it must have seemed more plausible. 14. The Tupolev crew had a first officer that suggested following TCAS instead, but he was not sitting in the RHS because there happened to be an extra Instructor Captain on that flight in the RHS who chose to follow ATC. 15. There happened to be a software upgrade at Zuerich ATC that night that disabled the Short-Term Conflict Alert light. 16. That software upgrade also disabled the phone lines, forcing the controller to waste time with the phone when trying to call Friedrichshafen for the delayed A320, and also prevented Karlsruhe ATC from warning Zuerich ATC of the problem. 17. ATC made a small, per se inconsequential, mistake of confusing "at your 2 o'clock" with "at your 10 o'clock". 18. The 757 crew waited 23 seconds to tell ATC that they were in a TCAS RA descent, by which time ATC was busy with the delayed A320. 19. The Tupolev crew was too busy/distracted to hear and understand that 757 TCAS RA descent call. 20. The ATC radar updated only every 12 seconds and did not yet reflect the 757's descent when ATC decided to instruct the Tupolev to descend. 21. The serious incident earlier in Japan with ATC/TCAS mismatch had not yet filtered through to all crews worldwide. It's just so unlikely.

Maxion 3y ago
You forgot the karlruhe controllers who saw it all, and tried to call but the phone lines were down. They obeyed protocol and didn’t contact the planes that weren’t in their sector,even though they could have.
- rossdavidh 3y ago
  It's a tough call. If they had contacted them, they also could have talked over instructions from the other sector's controller, for all they knew, which is presumably the reason for the protocol? Tough decision.
- seabass-labrax 3y ago
  I wonder whether, had they chosen to contact the aircraft outside their sector, the Skyguide controller would have heard them. With VHF radio being line of sight, the aircraft would probably have heard them, but Skyguide would be based at a ground station that was perhaps occluded by nearby mountains or other buildings. Where I live, I can't pick up a VHF ground station which is nearly in my line of sight only fifty kilometres away.
banannaise 3y ago
> It's just so unlikely. It's just so unlikely that this particular crash is the one that happens. A crash of this sort was all but inevitable, unless significant changes were made, and significant changes weren't going to be made until a crash of this sort happened. The article details a near-miss 17 months prior that would have killed 677 people. If this had been avoided as well, there would have been another a few months later, and another, and another, until one finally met all the conditions for an actual collision. Is it unlikely that the roulette wheel will land on 00 this time? Of course. Is it unlikely that it will ever land on 00? No!