Originally Posted by
JohnBurke
A favorite question in skydive circles, is to ask a jump student how long he has to deploy his reserve parachute, during a malfunction. The correct answer is "the rest of your life."
SR111 was 66 nm southwest of Halifax at the time of detection. They made the decision to divert to Boston, which was 300 miles south. Moncton control prompted them that Halifax was nearer. The crew elected to take Halifax. The crew call at the time was pan pan, not mayday, and the crew had not declared an emergency; they had smoke in the cockpit, but not reported in the cabin. Five minutes had elapsed at this point; 25% of the remainder of their lives. Note that at the time of detection (by scent); the crew had the remainder of their lives to handle the emergency. Historically we know that was twenty minutes. One quarter of that was used taking the time to decide where to go; a decision between diverting 300 miles south, or the closer Halifax. The pilots donned oxygen six minutes after detection.
The flight was cleared to 10,000' and then to 3,000' and a vector assigned; the crew replied that they needed more time to set up for landing. The crew was cleared to 3,000, but advised that they needed to stop at 8000 to take time to prepare the cabin for landing. At this point they had used half of their lifetime since identification of the scent of smoke, or approximately nine minutes.
At the 75% point in their remaining lifetime, or fifteen minutes after the first detection of the scent of smoke, the crew took a vector north, with the intent of dumping fuel. The pllots then took a turn south and advised that they were preparing for a fuel dump to reduce weight for landing, and would dump at 10,000'. They had about ten minutes left in their lifetime at that point, and were within 25 miles of the airport. With nine minutes left to live the crew took one more vector, and advised they were starting the fuel jettison.
The controller asked the pilots if they intended to remain close to the airport, or whether they intended to fly south away from the airport; the crew advised that they were willing to fly away from the airport for their fuel dump and thus took the south vectors away from the airport. It's worth noting that the both pilots were instructors, and the captain a check airman, for Swissair, though neither had ever experienced an inflight emergency, or there is no record or history of such experience. The crew was also aware that the aircraft could be landed overweight. It should also be noted that the MD11 has the fasted landing speeds of any commercial airliner. In any event, with the second vector, the crew couldn't know, but had eight minutes left to live when they reported level at 10,000'. At that point the crew began to run a smoke checklist.
Just shy of fourteen minutes into their lifetime since detection of the fire by scent, the crew declared an emergency, and were promptly advised the controller would get back to them in two minutes, or in 1/3 of their remaining lifetime. The crew acknowledged that, and at the same time advised they were starting the fuel dump. A minute later they declared an emergency again, now fifteen minutes after detection, having used 3/4 of their lifetime since detection to get to this point. The controller cleared them to dump fuel, but did not receive a response. No one would hear form them again. Just under six minutes later, an impact was both heard by observers and felt by seismographs.
Few of us know how much time we have left. How long to tell our loved ones that we care about them? In reality, the rest of our lives. Or theirs. Ten minutes? Ten hours? Ten years? We don't know that; it behooves us not to wait.
How long do we have to divert and land, rather than dump fuel, run checklists, prepare a cabin, take vectors, etc? We don't know. For SR111, the answer in retrospect is that they had just under 21 minutes.
When faced with a divert decision, the initial choice wasn't Halifax. It was Boston, 300 nm away. UPS 6 chose Dubai, their departure point, instead of Doha, nearby.
We pays our price, we takes our chances. Will they bear fruit? It's very possible that at the time of fire detection, we have the remainder of our life to sort it out. The longer we delay, the greater the chance that our remaining lifetime will be short. If we do nothing, we burn up, systems burn up, we die. We have to do something. The fire department isn't coming to us. We have to get to them. We can't pull over and ask for help. There's no bringing in additional resources; what we have at the outset is what we have to work with. We won't get to make assessments of what percentage of our lifetime (since detection) that we spent taking vectors away from the landing airport, dumping fuel, running checklists, preparing the cabin for landing, etc. But someone will. Investigators. Ground school instructors who use us as a life lesson. People on an internet web board. Someone will.
The Canadian report states in it's other section that the crew wouldn't have made it. This is not found in the primary report conclusions, but in the contributing factors; the Canadian report looks more closely at other factors, such as flame propagation, wiring, fire detection, and so forth. The Canadian report notes that the controllers didn't contribute to the mishap, though they did assign multiple vectors away from the airport, and the crew took them. Conversely, though not mentioned, has the controllers simply acquiesced to the pilot's choice, they'd have not prompted the crew to take Halifax, four five times closer to them than their initial decision, Boston.
Might the crew have made it, if they weren't flying away from the airport, leveling to dump fuel, running checklists, preparing the cabin for landing, etc? Would they have made it had they not waited until three quarters of their remaining time was over before they declared an emergency? Often, the declaration of an emergency (or mayday, vs. pan pan) marks the point in time where we've announced the seriousness with which we take the present occasion. There are certainly times when we will not be immediately aware, and there is always a sequence of events during which we continue to discover or learn of the progress of the situation. The crew in this case felt sure enough about their choices that they bet their life on those choices. They lost the bet.
This much we know: flying away from the airport will not get us closer to the airport. Taking time to jettison fuel is not time spent descending to land, or getting closer to the airport. Preparing the cabin is nice, but a tidy cabin loses its shine on impact. We may have never experienced an emergency, but the one that counts is the one right now. We can be a systems expert with a history of stressing the mechanics of smoke procedures, but that doesn't buy time, and that experience gets us no closer to the airport when we take vectors away from the airport and request a higher altitude and to stop our descent, and choose to prioritize fuel jettison over a landing.
There is no throwing the crew under the bus. They're dead. Their actions and choices and the results, are a matter of record. From the time of detection, they had the rest of their lives to get on the ground and evacuate. They chose to spend the rest of their lives taking vectors, flying away from the airport, preparing the cabin for landing, running checklists, and asking for delaying vectors, because they weren't prepared to land. This is part of the record. Call it what you will. It doesn't change the fact.