6 ms·

Virgin Galactic Executive Summary of Submission on SpaceShipTwo Accident

79 points by aerocapture 11y ago

aerocapture 11y ago
> "When accomplished at 1.4 Mach or greater (as required per the SpaceShipTwo checklist procedures and the PF-04 test card) the feather system remained retracted due to a sufficient closing pre-load from the feather actuators and favorable, tail-down aerodynamic loads." > "On normal rocket-powered flights, checklist procedures called for this step to occur after rocket motor burn out while in space just prior to apogee." I still haven't seen any information on exactly why this particular flight test card called for actuating the feather mechanism at some time other than apogee. Were they trying to test the flying qualities while feathered at a particular dynamic pressure? It doesn't make any sense for the copilot to move the unlock lever while the aircraft was still accelerating unless the test card called for it. And if it did, then did the engineers and test planners fail to take this possible failure mode into account before the flight?
- erobbins 11y ago
  The feather is always unlocked during ascent, in order to make sure the unlock mechanism works. If the unlock mechanism fails at apogee, the ship will not be able to decelerate appropriately and will overspeed and break up in reentry.
robertfw 11y ago
The full transcripts were posted on the nasa spaceflight forum here: http://forum.nasaspaceflight.com/index.php?topic=35974.440 http://forum.nasaspaceflight.com/index.php?topic=35974.440. One user provided the following summary: > There was corporate conversational knowledge that unlocking the feather system during the transonic region would be catastrophic, but this knowledge wasn't formalized into the pilot handbook or in training. There was formal knowledge that unlocking late would lead to a flight abort, and a recent event had occurred where the unlock was late. Add to this copilot workload increases between flights, the fact that training wasn't done in the suits and equipment worn on the real flight or under the g and vibration loads in the flight, and the result was the copilot unlocked the feather early leading to the loss of the vehicle. As usual, not a single failure, but a chain of smaller failures - lack of formalization of knowledge, lack of training in the operational environment, recent events, pressure to avoid an abort, and you get an overcompensation.
- narrator 11y ago
  They should just do all this in software. Anything that that's complex and life or death should be autopilot driven.
  - Dylan16807 11y ago
    And then you get an autopilot that under abnormal conditions doesn't realize it should deploy the parachute...
    - GauntletWizard 11y ago
      Almost everything an autopilot should do should have a button and a switch for humans. The switch prevents the autopilot from doing it, the button makes it happen. This isn't to disparage autopilots, but to assure control. The human should always be in control of the system, and capable of deciding when things happen.
      - tedunangst 11y ago
        And in this case, would have pushed the button too early, resulting in the exact same outcome.
        chronic40 11y ago
        Lol. Got em
        rwallace 11y ago
        No, in this case, by far the most likely outcome is the autopilot would have pushed the button at the right time, creating no need for the copilot to override it.
        tedunangst 11y ago
        How do you figure? Pilot thinks "I think it's time to push the button." Autopilot doesn't push button. Pilot says "autopilot is broken. I need to override." Pilot pushes button early. If the pilot thinks the button needs pushing, they're not going to wait til after the crash to see if the autopilot is working.
zapt02 11y ago
A little OT, but the contrast between SpaceX and The Spaceship Company is striking. Elon Musk is pushing for interstellar travel, while Branson is pushing for space tourism. Seems so petty in comparison.
- nesyt 11y ago
  Maybe space tourism increases public interest in interstellar travel?
  - georgemcbay 11y ago
    Extremely likely due to the overview effect. https://en.wikipedia.org/wiki/Overview_effect https://en.wikipedia.org/wiki/Overview_effect
- pyre 11y ago
  If Branson is able to make space flight mundane (b/c so many people do it) and/or put "a resort on the moon," I can't see how that wouldn't push things forward.
- guelo 11y ago
  I don't really follow SpaceX to know what Elon Musk is pushing for, but as a practical engineer it seems unlikely that he would be pushing for something that is outside the realm of what physics considers at all possible.
  - djloche 11y ago
    SpaceX has a current mission of reducing launch costs and providing low-cost launch services, with a long term goal of helping humanity settle other planets (mars being the first, perhaps only planet mentioned right now). Interplanetary is well within our realm. Interstellar, not currently.
    - guelo 11y ago
      So then zapt02 misspoke.
deleted 11y ago
[deleted]
nulltype 11y ago
Why are these ships manned?
- melling 11y ago
  You're the second guy to say this. Stop and think... Ready for it? Because it was only months away from carrying tourists. You'll scare the tourists if you're afraid to use a human pilot.
  - nulltype 11y ago
    I bet the tourists are pretty scared now.
    - drusenko 11y ago
      Said tourist checking in. Still keeping my ticket I purchased over 4 years ago. Space is hard and I'll go when they're ready.
      - Intermernet 11y ago
        Sorry for the irrelevant comment, but I'm so jealous! I hope you have a great (and safe) ride!
    - ablation 11y ago
      Only 3% have asked for refunds as of 5th November last year[1]. Could be more now, of course, but demand is still high. They'll sell the returns no matter what. [1]http://www.theguardian.com/science/2014/nov/05/virgin-galactic-seatholders-ask-for-refund-on-tickets http://www.theguardian.com/science/2014/nov/05/virgin-galact...
    - raverbashing 11y ago
      One of the reasons why people can take a cheap flight across continents today is because people risked their lives trying it. Of course, today there's automation, but it only goes so far Somebody has to take the first step
vilhelm_s 11y ago
The NTSB findings and recommendations: http://www.ntsb.gov/news/events/Documents/2015_spaceship2_BMG_abstract.pdf http://www.ntsb.gov/news/events/Documents/2015_spaceship2_BM...
vilhelm_s 11y ago
The NTSB findings and recommendations: http://www.ntsb.gov/news/events/Documents/2015_spaceship2_BMG_abstract.pdf http://www.ntsb.gov/news/events/Documents/2015_spaceship2_BM...
znep 11y ago

79 points by aerocapture 11y ago

> "When accomplished at 1.4 Mach or greater (as required per the SpaceShipTwo checklist procedures and the PF-04 test card) the feather system remained retracted due to a sufficient closing pre-load from the feather actuators and favorable, tail-down aerodynamic loads." > "On normal rocket-powered flights, checklist procedures called for this step to occur after rocket motor burn out while in space just prior to apogee." I still haven't seen any information on exactly why this particular flight test card called for actuating the feather mechanism at some time other than apogee. Were they trying to test the flying qualities while feathered at a particular dynamic pressure? It doesn't make any sense for the copilot to move the unlock lever while the aircraft was still accelerating unless the test card called for it. And if it did, then did the engineers and test planners fail to take this possible failure mode into account before the flight?

erobbins 11y ago
The feather is always unlocked during ascent, in order to make sure the unlock mechanism works. If the unlock mechanism fails at apogee, the ship will not be able to decelerate appropriately and will overspeed and break up in reentry.

robertfw 11y ago

The full transcripts were posted on the nasa spaceflight forum here: http://forum.nasaspaceflight.com/index.php?topic=35974.440 http://forum.nasaspaceflight.com/index.php?topic=35974.440. One user provided the following summary: > There was corporate conversational knowledge that unlocking the feather system during the transonic region would be catastrophic, but this knowledge wasn't formalized into the pilot handbook or in training. There was formal knowledge that unlocking late would lead to a flight abort, and a recent event had occurred where the unlock was late. Add to this copilot workload increases between flights, the fact that training wasn't done in the suits and equipment worn on the real flight or under the g and vibration loads in the flight, and the result was the copilot unlocked the feather early leading to the loss of the vehicle. As usual, not a single failure, but a chain of smaller failures - lack of formalization of knowledge, lack of training in the operational environment, recent events, pressure to avoid an abort, and you get an overcompensation.

narrator 11y ago
They should just do all this in software. Anything that that's complex and life or death should be autopilot driven.
- Dylan16807 11y ago
  And then you get an autopilot that under abnormal conditions doesn't realize it should deploy the parachute...
  - GauntletWizard 11y ago
    Almost everything an autopilot should do should have a button and a switch for humans. The switch prevents the autopilot from doing it, the button makes it happen. This isn't to disparage autopilots, but to assure control. The human should always be in control of the system, and capable of deciding when things happen.
    - tedunangst 11y ago
      And in this case, would have pushed the button too early, resulting in the exact same outcome.
      - chronic40 11y ago
        Lol. Got em
      - rwallace 11y ago
        No, in this case, by far the most likely outcome is the autopilot would have pushed the button at the right time, creating no need for the copilot to override it.
        tedunangst 11y ago
        How do you figure? Pilot thinks "I think it's time to push the button." Autopilot doesn't push button. Pilot says "autopilot is broken. I need to override." Pilot pushes button early. If the pilot thinks the button needs pushing, they're not going to wait til after the crash to see if the autopilot is working.

zapt02 11y ago

A little OT, but the contrast between SpaceX and The Spaceship Company is striking. Elon Musk is pushing for interstellar travel, while Branson is pushing for space tourism. Seems so petty in comparison.

nesyt 11y ago
Maybe space tourism increases public interest in interstellar travel?
- georgemcbay 11y ago
  Extremely likely due to the overview effect. https://en.wikipedia.org/wiki/Overview_effect https://en.wikipedia.org/wiki/Overview_effect
pyre 11y ago
If Branson is able to make space flight mundane (b/c so many people do it) and/or put "a resort on the moon," I can't see how that wouldn't push things forward.
guelo 11y ago
I don't really follow SpaceX to know what Elon Musk is pushing for, but as a practical engineer it seems unlikely that he would be pushing for something that is outside the realm of what physics considers at all possible.
- djloche 11y ago
  SpaceX has a current mission of reducing launch costs and providing low-cost launch services, with a long term goal of helping humanity settle other planets (mars being the first, perhaps only planet mentioned right now). Interplanetary is well within our realm. Interstellar, not currently.
  - guelo 11y ago
    So then zapt02 misspoke.

deleted 11y ago

[deleted]

nulltype 11y ago

Why are these ships manned?

melling 11y ago
You're the second guy to say this. Stop and think... Ready for it? Because it was only months away from carrying tourists. You'll scare the tourists if you're afraid to use a human pilot.
- nulltype 11y ago
  I bet the tourists are pretty scared now.
  - drusenko 11y ago
    Said tourist checking in. Still keeping my ticket I purchased over 4 years ago. Space is hard and I'll go when they're ready.
    - Intermernet 11y ago
      Sorry for the irrelevant comment, but I'm so jealous! I hope you have a great (and safe) ride!
  - ablation 11y ago
    Only 3% have asked for refunds as of 5th November last year[1]. Could be more now, of course, but demand is still high. They'll sell the returns no matter what. [1]http://www.theguardian.com/science/2014/nov/05/virgin-galactic-seatholders-ask-for-refund-on-tickets http://www.theguardian.com/science/2014/nov/05/virgin-galact...
  - raverbashing 11y ago
    One of the reasons why people can take a cheap flight across continents today is because people risked their lives trying it. Of course, today there's automation, but it only goes so far Somebody has to take the first step

vilhelm_s 11y ago

The NTSB findings and recommendations: http://www.ntsb.gov/news/events/Documents/2015_spaceship2_BMG_abstract.pdf http://www.ntsb.gov/news/events/Documents/2015_spaceship2_BM...

vilhelm_s 11y ago

The NTSB findings and recommendations: http://www.ntsb.gov/news/events/Documents/2015_spaceship2_BMG_abstract.pdf http://www.ntsb.gov/news/events/Documents/2015_spaceship2_BM...

znep 11y ago