5 ms·

To clarify, the FAA is grounding it because it flew outside the flight corridor, which could cause risk to the general public. The FAA grounding has nothing to

To clarify, the FAA is grounding it because it flew outside the flight corridor, which could cause risk to the general public. The FAA grounding has nothing to do with whether there was risk to the occupants or not.

Dylan16807 5y ago
Leaving your flight corridor twenty miles up cannot cause risk to the general public. Also are there better explanations of the flight corridor shape somewhere? I'm confused about how cutting the engines would have helped stay inside it.
- nickhalfasleep 5y ago
  If they cannot properly plot their route, then what else did they get wrong? This could easily cause them to rain dead billionaires all over someone's house.
  - Dylan16807 5y ago
    If it's a grounding because of the failure, and they would also be grounded if they had aborted just before leaving the flight corridor, I think that logic works. But that's not a great explanation if the grounding is specifically for leaving the flight corridor.
    - nraynaud 5y ago
      They could declare an emergency if they abort. Then nobody will look at the zoning during the investigation, and they get to ask whatever they want from the ATC who will simultaneously keep all the other aircrafts clear of the zone (also it New Mexico, so the uncontrolled zoning is weird)
- Denvercoder9 5y ago
  > Leaving your flight corridor twenty miles up cannot cause risk to the general public. As long as they're able to get back into their flight corridor before they're at an altitude where others fly.
  - Dylan16807 5y ago
    Well it says they were out for less than two minutes so it sounds like they managed that?
    - TheOtherHobbes 5y ago
      They shouldn't have needed to "manage it". It's like saying someone "managed" to drive the wrong way down a freeway for a mile or two. Even if it was at 3am and there was no other traffic "no harm" doesn't apply, because it shouldn't have happened.
      - Dylan16807 5y ago
        Correct that it shouldn't happen, but if this is a road where they only allow one car on a month then driving on the wrong side isn't really dangerous.
- zlsa 5y ago
  I don't have any knowledge about Virgin Galactic's trajectory, but in general rocket trajectories are chosen such that no matter where the rocket fails along its flight, it will either fall entirely within the published keep-out zone (and cause no harm to humans, since the zone is cleared before launch), or are going fast enough to break apart during reentry and will not cause harm to humans (since the majority of the vehicle is just particles in the air, or very small pieces.) Obviously Virgin Galactic's vehicle can't be terminated since it's crewed, so I'd expect that the keep-out zone is designed so that at any point thrust can be cut and the vehicle will remain within its allowed airspace. Again, I have no knowledge about the flight corridor they are using, but if we imagine it's a two-level volume with a large (but low-altitude) cylinder, and a small (but high-altitude cylinder), it's possible that the trajectory extends beyond the small, high-altitude cylinder while still above the ceiling of the large, low-altitude cylinder. If that's the case (and I'm definitely not saying it was!), then if the vehicle velocity has too much of a horizontal component during the engine burn, it will exceed the limits of its allotted airspace unless the engine is shut down (in which case it won't be going fast enough to exceed the limits.) Again, this is probably not exactly what happened; it's just an example of how an early engine shutdown could prevent them from violating airspace.
- Rebelgecko 5y ago
  >Leaving your flight corridor twenty miles up cannot cause risk to the general public. To me it seems like there's very straightforward cases where it can (e.g. crashing into an elementary school vs unpopulated desert). That's why most rockets carry flight termination systems.
  - Dylan16807 5y ago
    If it's safe enough to let people be on the rocket, I don't know if the risk of hitting a building outside the flight corridor is high enough to be important. I'd appreciate numbers, I guess.
    - xigency 5y ago
      > I don't know if the risk of hitting a building outside the flight corridor is high enough to be important. It is. From the New Yorker post: “The Federal Aviation Administration regulates the private space industry and sets aside airspace for each mission, seeking to prevent collisions with general air traffic, including commercial airliners, and to limit civilian casualties in the event of an accident. The regulator uses formulas detailed in a hundred-and-twenty-one-page document—including an equation for calculating expected casualties—to assess the safety of a given spaceflight. According to the F.A.A., an acceptable Ec, as the equation is called, involves no more than one expected casualty per ten thousand missions.” So there needs to be less than a 0.01% chance of killing someone on the ground. As a bystander on the ground, that seems an acceptable level of risk to tolerate for someone else’s joyride.
      - Dylan16807 5y ago
        I saw that, but I'm not convinced that the course deviation endangered anyone on the ground. It might have screwed up the landing, but that's not the same thing.
        kyralis 5y ago
        Fortunately, you're not the one they need to convince. The FAA is doing an investigation to see if they could have, and then they'll make a decision, rather than jumping to conclusions.
- jcrawfordor 5y ago
  Space flights don't really get a flight plan per se. Instead they just use various special use airspace - that is, in a sense, they fly uncontrolled but within an area reserved for that purpose. One of the appeals of Spaceport America is that it is already surrounded by restricted airspace for the White Sands Missile Range, but the Spaceport itself is located near the western edge of WSMR. The WSMR's main restricted areas are always hot and have a general reputation for being difficult to enter (although ZAB does apparently give permission to airliners in the flight levels from time to time), but the Spaceport itself is located under restricted airspace that's only hot by NOTAM. I've flown around the area a number of times. It's actually a relatively busy area for general aviation, by New Mexico standards, because TorC municipal (KTCS) is a fairly popular airport with both paved and dirt runways and a lot of light aircraft like to go sightseeing over Elephant Butte reservoir. Back when I first got my ticket flying down to TorC and around the lake was a standard cross country solo. The flight was issued a TFR covering an area generally west of the existing R-5111, and additionally of course all of R-5111 (A,B,C,D) was activated (this is a normal White Sands Missile Range restricted area). I drew the TFR here since the FAA version with the drawing is gone: https://jbcrawford.us/f/HIGE-ivkmLprESd.jpg https://jbcrawford.us/f/HIGE-ivkmLprESd.jpg. I'm having a hard time finding any information on SpaceShipTwo's flight path from the Spaceport (I could find info on the typical flight plan from Mojave), but it's presumably to the north given the position of the Spaceport and its runway alignment. Given what I understand of the flight path for SpaceShipTwo, the major concern would be overrunning the special use airspace at the north end. That's inherently a bit risky because at low altitude a lot of GA traffic follows the Rio Grande, up at the flight levels it's probably not so big of a concern because a lot of commercial traffic has to go around further north (R-5107 C, the high altitude part of R-5107, is active continuously weekdays even though the WSMR north "call-up area" is rarely used). But because of the huge implications of a safety incident with commercial traffic the FAA is pretty careful about class A airspace. That's all getting into the weeds, but more to the point: what happens at "20 miles up" is not really the concern, that's actually outside of class A airspace and you can go back to VFR if you're up that high and, you know, can. The problem is that SpaceShipTwo returns via an unpowered glide, at pretty extreme performance, and so doesn't have much ability to maneuver for a lot of the return path. Being outside of envelope on the way up could cause it to come back down, later, through class A airspace with no TFR. If that's far enough north it could indeed be in a fairly busy corridor for commercial aircraft (coming around the top of R-5107 C&H) which is a dangerous situation indeed.
paul_f 5y ago
The flight spent over a minute in Class A airspace. You cannot do that without getting into serious trouble with the FAA.
- aero-glide2 5y ago
  There were no other flights nearby. Sounds like much ado about nothing.
  - onion2k 5y ago
    As a general rule, you want flights to be safe by sticking to their agreed plan rather than by being lucky that there wasn't something to hit.
- gpvos 5y ago
  Apparently you can, unless the New Yorker writes about it.

Dylan16807 5y ago

Leaving your flight corridor twenty miles up cannot cause risk to the general public. Also are there better explanations of the flight corridor shape somewhere? I'm confused about how cutting the engines would have helped stay inside it.

nickhalfasleep 5y ago
If they cannot properly plot their route, then what else did they get wrong? This could easily cause them to rain dead billionaires all over someone's house.
- Dylan16807 5y ago
  If it's a grounding because of the failure, and they would also be grounded if they had aborted just before leaving the flight corridor, I think that logic works. But that's not a great explanation if the grounding is specifically for leaving the flight corridor.
  - nraynaud 5y ago
    They could declare an emergency if they abort. Then nobody will look at the zoning during the investigation, and they get to ask whatever they want from the ATC who will simultaneously keep all the other aircrafts clear of the zone (also it New Mexico, so the uncontrolled zoning is weird)
Denvercoder9 5y ago
> Leaving your flight corridor twenty miles up cannot cause risk to the general public. As long as they're able to get back into their flight corridor before they're at an altitude where others fly.
- Dylan16807 5y ago
  Well it says they were out for less than two minutes so it sounds like they managed that?
  - TheOtherHobbes 5y ago
    They shouldn't have needed to "manage it". It's like saying someone "managed" to drive the wrong way down a freeway for a mile or two. Even if it was at 3am and there was no other traffic "no harm" doesn't apply, because it shouldn't have happened.
    - Dylan16807 5y ago
      Correct that it shouldn't happen, but if this is a road where they only allow one car on a month then driving on the wrong side isn't really dangerous.
zlsa 5y ago
I don't have any knowledge about Virgin Galactic's trajectory, but in general rocket trajectories are chosen such that no matter where the rocket fails along its flight, it will either fall entirely within the published keep-out zone (and cause no harm to humans, since the zone is cleared before launch), or are going fast enough to break apart during reentry and will not cause harm to humans (since the majority of the vehicle is just particles in the air, or very small pieces.) Obviously Virgin Galactic's vehicle can't be terminated since it's crewed, so I'd expect that the keep-out zone is designed so that at any point thrust can be cut and the vehicle will remain within its allowed airspace. Again, I have no knowledge about the flight corridor they are using, but if we imagine it's a two-level volume with a large (but low-altitude) cylinder, and a small (but high-altitude cylinder), it's possible that the trajectory extends beyond the small, high-altitude cylinder while still above the ceiling of the large, low-altitude cylinder. If that's the case (and I'm definitely not saying it was!), then if the vehicle velocity has too much of a horizontal component during the engine burn, it will exceed the limits of its allotted airspace unless the engine is shut down (in which case it won't be going fast enough to exceed the limits.) Again, this is probably not exactly what happened; it's just an example of how an early engine shutdown could prevent them from violating airspace.
Rebelgecko 5y ago
>Leaving your flight corridor twenty miles up cannot cause risk to the general public. To me it seems like there's very straightforward cases where it can (e.g. crashing into an elementary school vs unpopulated desert). That's why most rockets carry flight termination systems.
- Dylan16807 5y ago
  If it's safe enough to let people be on the rocket, I don't know if the risk of hitting a building outside the flight corridor is high enough to be important. I'd appreciate numbers, I guess.
  - xigency 5y ago
    > I don't know if the risk of hitting a building outside the flight corridor is high enough to be important. It is. From the New Yorker post: “The Federal Aviation Administration regulates the private space industry and sets aside airspace for each mission, seeking to prevent collisions with general air traffic, including commercial airliners, and to limit civilian casualties in the event of an accident. The regulator uses formulas detailed in a hundred-and-twenty-one-page document—including an equation for calculating expected casualties—to assess the safety of a given spaceflight. According to the F.A.A., an acceptable Ec, as the equation is called, involves no more than one expected casualty per ten thousand missions.” So there needs to be less than a 0.01% chance of killing someone on the ground. As a bystander on the ground, that seems an acceptable level of risk to tolerate for someone else’s joyride.
    - Dylan16807 5y ago
      I saw that, but I'm not convinced that the course deviation endangered anyone on the ground. It might have screwed up the landing, but that's not the same thing.
      - kyralis 5y ago
        Fortunately, you're not the one they need to convince. The FAA is doing an investigation to see if they could have, and then they'll make a decision, rather than jumping to conclusions.
jcrawfordor 5y ago
Space flights don't really get a flight plan per se. Instead they just use various special use airspace - that is, in a sense, they fly uncontrolled but within an area reserved for that purpose. One of the appeals of Spaceport America is that it is already surrounded by restricted airspace for the White Sands Missile Range, but the Spaceport itself is located near the western edge of WSMR. The WSMR's main restricted areas are always hot and have a general reputation for being difficult to enter (although ZAB does apparently give permission to airliners in the flight levels from time to time), but the Spaceport itself is located under restricted airspace that's only hot by NOTAM. I've flown around the area a number of times. It's actually a relatively busy area for general aviation, by New Mexico standards, because TorC municipal (KTCS) is a fairly popular airport with both paved and dirt runways and a lot of light aircraft like to go sightseeing over Elephant Butte reservoir. Back when I first got my ticket flying down to TorC and around the lake was a standard cross country solo. The flight was issued a TFR covering an area generally west of the existing R-5111, and additionally of course all of R-5111 (A,B,C,D) was activated (this is a normal White Sands Missile Range restricted area). I drew the TFR here since the FAA version with the drawing is gone: https://jbcrawford.us/f/HIGE-ivkmLprESd.jpg https://jbcrawford.us/f/HIGE-ivkmLprESd.jpg. I'm having a hard time finding any information on SpaceShipTwo's flight path from the Spaceport (I could find info on the typical flight plan from Mojave), but it's presumably to the north given the position of the Spaceport and its runway alignment. Given what I understand of the flight path for SpaceShipTwo, the major concern would be overrunning the special use airspace at the north end. That's inherently a bit risky because at low altitude a lot of GA traffic follows the Rio Grande, up at the flight levels it's probably not so big of a concern because a lot of commercial traffic has to go around further north (R-5107 C, the high altitude part of R-5107, is active continuously weekdays even though the WSMR north "call-up area" is rarely used). But because of the huge implications of a safety incident with commercial traffic the FAA is pretty careful about class A airspace. That's all getting into the weeds, but more to the point: what happens at "20 miles up" is not really the concern, that's actually outside of class A airspace and you can go back to VFR if you're up that high and, you know, can. The problem is that SpaceShipTwo returns via an unpowered glide, at pretty extreme performance, and so doesn't have much ability to maneuver for a lot of the return path. Being outside of envelope on the way up could cause it to come back down, later, through class A airspace with no TFR. If that's far enough north it could indeed be in a fairly busy corridor for commercial aircraft (coming around the top of R-5107 C&H) which is a dangerous situation indeed.

paul_f 5y ago

The flight spent over a minute in Class A airspace. You cannot do that without getting into serious trouble with the FAA.

aero-glide2 5y ago
There were no other flights nearby. Sounds like much ado about nothing.
- onion2k 5y ago
  As a general rule, you want flights to be safe by sticking to their agreed plan rather than by being lucky that there wasn't something to hit.
gpvos 5y ago
Apparently you can, unless the New Yorker writes about it.