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SpaceShipTwo Pilot Was Unaware Co-Pilot Had Unlocked Brakes

LOS ANGELES (AP) — The pilot of the Virgin Galactic spaceship that tore apart over the Mojave Desert didn’t know his co-pilot had prematurely unlocked its brakes, despite protocol requiring the co-pilot to announce the step. Pilot Peter Siebold told the National Transportation Safety Board that he wasn’t aware co-pilot Mike Alsbury unlocked the brakes before the rocket was done accelerating. Seconds later, SpaceShipTwo began to disintegrate. ( More...

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I know SS2 is an extreme example, but AFR447 also demonstrated that ineffective communication amongst flight crew can have disastrous consequences.
sparkie624 2
Very much so....
M.F. LaBoo 5
A couple of comments. First, "brakes" is a misleading term in this context. Should at least be "airbrakes". The feathering system is to add drag on reentry from space to keep the speed down so the composite airframe doesn't overheat on re-encountering the atmosphere. That would cause it to delaminate, resulting in the loss of the craft and its occupants.

Next, the feathers need to be unlocked within a narrow window during the burn. The book calls for them to wait until Mach 1.4 but feather unlocking capability has to be confirmed before reaching a certain speed, because as noted, the feathers must work on reentry. If the unlocking fails during this ascent window, the flight has to be aborted.

Now it appears the feathers were unlocked at Mach 1.04, still in the transonic buffeting range. The changing and unpredictable airflow in that range may have overcome the actuators' ability to hold the feathers in position till actual deployment is commanded. The reason for the "early" unlock is still not known, could be a faulty Mach reading, could be cockpit vibration made it hard to read the display (hybrid motors tend to set up harmonic vibrations), could be PE.

On top of all that, although neither the nitrous tank nor the motor chamber apparently ruptured/exploded, some photos seem to indicate there may have been some sort of failure in the plumbing. That would've overpressured the airframe and caused a rapid disassembly. So the jury's still out.

One more point, there's no ejection system, just personal chutes. The surviving pilot found himself in midair after the cabin disintegrated around him -- at 50K feet, without a pressure suit, and (apparently) without O2. He's lucky to still be with us.
John Taylor 2
Well done MF Thank you. Your comments are very illuminating esp. the 1.4 vs 1.04!
Mark Lansdell 1
While I don't take issue with your comments nor analysis, I do think you're underestimating the people on this site. Most are pretty intelligent professional pilots with a sprinkling of talented, inventive and smart maintenance professionals. I would pit most of them with aeronautical engineers in discussions.

I think every one here understands that brakes is a shortened version of the term, and the feathering system was pretty well defined in the article. The rest of what you write is redundant to the article as well other than the pilot surviving free fall from
fl 50.0.

It's obvious that the investigation is in it's rudimentary stages as the first order of business is to interpret the information from the black boxes which I'll remind you are not black at all. I mentioned in a posting below that NTSB has not yet but will listen to the CVR tapes, which may or may not be tapes, next week. That information should solve many questions and bring new ones to the table, which table is non-existent.
M.F. LaBoo 3
Were we looking at the same article? None of the details in my post are in the skeletal mass-media article linked above, nor in any of the posts below. The feathering system is unique to SS1 and 2 and doesn't have any precise counterpart in airbreathing aircraft, so I felt some details might be helpful. Clarity and specificity are good things, wouldn't you agree?

I'm well aware that many posters here are professionals with the training and expertise you cite, and that's one reason I don't submit idle, speculative posts. Here my intention was to provide information not found in the article or in these comments, at a level that wasn't disrespectful to this readership -- let alone condescending, as your reply comes pretty close to being.

One of *my* areas of expertise is hybrid rocket motor design, and there's considerable discussion in other forums related to VG's motor design and testing decisions -- but that, I did indeed deem "off-point" in this forum.

I make no pretense of being a mindreader and have no way of determining what posters or readers may already know, except for the contents of the posts themselves. I'm well aware that the NTSB investigation has only begun, which is precisely why I noted that "the jury is still out". I offer no apologies for my post.
John Taylor 2
Once again're right on target!
As I continue to watch/learn I am a bit surprised at the apparent "tenderness" of the airframe components. My area of knowledge is the RF4-C "Phantom". The slowest one I ever flew easily attained mach 2.37 and you could readily maneuver at that speed with absolutely no fear of structural problems; and that included use of the speed brakes. I realize you addressed this in your third sentence....this is just a comment.
I appreciate the language you chose in your post. I'm a student pilot. What you wrote allowed me to understand and kept it very basic. Thank you! Anthony
Rick Dupre 3
Might be good to change the procedure to require two actions from different crewmembers to execute critical functions.
Mark Lansdell 0
I can't think of a better way to kill someone. Suppose one of the crew members is incapacitated. The surviving or functioning crew member is doomed because the other, required crewman could not function as needed. Training a d discipline just the way you were taught how to handle engine out on takeoff, stalls, etc.
John Taylor 2
Re-read second sentence; I addressed incapacitation! Crew coordination is always essential and critical...but there's only one guy in command and it appears in this case the CP took the AC out of loop. That being said:........subject to the constaints of Co. guide lines and published procedures the AC has broad powers of deligation; but that doesn't seem to apply here.
Mark Lansdell 1
Mr. Taylor. I was responding to the post over top of mine. I don't recall reading yours never mind responding to it. However, now that you have jumped in. The authority of the PIC must be respected and that is accomplished through discipline and redundancy. If the FO or copilot unlocked the breaking system prematurely It doesn't sound like the PIC authorize the action. It seems to me the CVR should solve this mystery, but I see the CVR will not be listened to until "next week". It appears that all this commentary is based on conjecture and a network, "news report" of a slow news day or the need to be first. There is little sense in sorting fly poop and black pepper in a report on an investigation that has hardly begun.
John Taylor 1
Bernie20910 1
While it does indeed seem to have broken, it is a "braking" system.
John Taylor 2
It's about "challenge and response"! Absent that, these things will continue to happen. Unless specifically pre-briefed, I can't think of a single situation, other than pilot incapacitation, where a co-pilot should act on-his-own.
joel wiley 3
Hit the wrong switch maybe?
jmilleratp 3
It would be a good idea to develop a safety mechanism that prevents unlocking of the brakes while the rocket is engaged.
Yeah really John, I cannot operate my builtin GPS on my 2014 Chev Impala while in driving mode, surely a vehicle that costs a hell of a lot more money than my car should have something similar!!
Yes, something that important should have been a high priority in the engineering .
Torsten Hoff 1
But what do you do if the system falsely believes the rockets are still firing? That would keep you from deploying the brakes when you might really need them. There has to be an override mechanism.
Maybe each pilot has a switch and it takes both. Of course a separate override available in case one pilot goes to lunch.
R.W. Mann 3
Atmospheric pressure lockout? Switch position annunciator?
BobRose 1
What's all this pre-flight stuff any way? D'oh!
Bernie20910 1
What brakes are they talking about, and how did that contribute to the accident?
The feathering system which helps slow and properly align the craft for reentry and landing.
Bernie20910 1
I guess the next question I have is, does unlocking them actually activate them?
Leo Cotnoir 1
Proving once again that space is not place for amateurs.
How is it certain that a malfunction in the instrument was not the cause of a premature unlocking of the brakes. Since Mike
Alsbury the co-pilot was a seasoned pilot, he would have known to make that announcement before the unlocking.
As the pilot stated no announcement was made.
André Schyns 0
Bravo ce site est très bien construit
Mark Lansdell 0
"When I was an Air Cadet a pure and simple lad,
My Chaplin told me how to tell the good life from the bad.
He patted me upon the can, he saved these words for last.
"Son don't ever fly too high and never fly too fast"".
John Taylor 1
"Air Cadet"?? Except in the movies; never heard of "Air Cadet"! Try "Aviation Cadet"! Over?
chalet 0
NASA and the Soviets started sending dogs and monkeys to space back in the 40s and 50s, and then human beings. A rocket is a rocket, a very dangerous artifact.


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