According to flightaware it's a Airbus A300F4-600 (twin-jet) (H/A306/QWas the tailwind comment a humorous one? As long as you're flying, from the perspective of the airflow over the wing, there is never a "tailwind", only forward airflow measured as airspeed.
They where having spoiler problems, like a while ago with a A320 where #4 spoiler element remained in the upright position. Might be frost or to much tailwind... :|
Was the tailwind comment a humorous one? As long as you're flying, from the perspective of the airflow over the wing, there is never a "tailwind", only forward airflow measured as airspeed.
QuoteWas the tailwind comment a humorous one? As long as you're flying, from the perspective of the airflow over the wing, there is never a "tailwind", only forward airflow measured as airspeed.
That is now exactly what I am afraid about, when spoilers are active during a turn (roll) they disrupt the airflow to reduce lift on that side. When this disruptive airflow starts to rotate towards the backside of a spoiler (due to wingfoil) and lifts it up and into a locked position. So far only Airbus has had this and they have a exclusive wingshape (foil). So it has not (yet) been confirmed, but I am a litte afraid it would be possible. If this would be studied with a tailwind then I have no idea what will come out. (windtunnel vision)
PASSENGER AIRCRAFT ARE DESIGNED SO THAT THEY WILL STILL FLY AND REMAIN
CONTROLLABLE EVEN IF ALL THE SPOILERS ARE DEPLOYED.
Very true but as the story says there was a uncommanded roll, like landing with or without gear it should not happen, but very rare it does. I bless the PF for recognizing the problem immediately and acted accordingly, I would never be afraid to fly with a pilot like this one :lol:
That is now exactly what I am afraid about, when spoilers are active during a turn (roll) they disrupt the airflow to reduce lift on that side. When this disruptive airflow starts to rotate towards the backside of a spoiler (due to wingfoil) and lifts it up and into a locked position. So far only Airbus has had this and they have a exclusive wingshape (foil). So it has not (yet) been confirmed, but I am a litte afraid it would be possible.Can I ask where your information is coming from that this has been an issue with Airbus aircraft? I agree with your description of how asymmetric spoiler deployment is used to provide/enhance rolling moments in some aircraft designs, but your assertion that the disrupted airflow can roll back and push a spoiler up doesn't sound right. Can you reference any specific reports, examples, or technical data that describes this phenomenon, or are you just guessing?
If this would be studied with a tailwind then I have no idea what will come out. (windtunnel vision)I really think you are misunderstanding what a "tailwind" means with respect to the airflow flowing over a wing. An aircraft in flight - even in a "tailwind" - is still always moving forward through a mass of air, and the air is always flowing from the front to the back of the wing.
With a tail wind going in the same (or near same) direction of the airplane at 20-40 kts I assume the vortex (wake) has more difficulty leaving the wing.No, that's not a correct assumption. The aircraft moves through an air mass at a given airspeed regardless of which way the air mass is moving relative to the ground, i.e. the "wind direction". At a given airspeed, vortices act the same relative to the wing, regardless of wind direction over the ground.
In normal flight this "backpressure" helps the airplane to move foreward...No. Wing vortices are actually a source of drag, which impedes the aircraft from moving forward. One of the purposes of winglets and tip-tanks is to reduce wingtip vortices, which likewise reduces drag and increases efficiency.
...but when this UPS was descending they encountered an uncommanded roll due to spoiler problems. As you should know with descending you try not to speed up, rather slowing down a bit. Then how can an uncommanded roll start with nothing there but air?What I've been responding to are your comments that "this disruptive airflow starts to rotate towards the backside of a spoiler (due to wingfoil) and lifts it up and into a locked position", and also that a tailwind can have any effect at all on the performance or action of a spoiler. Neither of these assertions are aerodynamically correct.
This reminds me of the thread where we were discussing whether a controller can ever declare and emergency for a pilot. Seems like once they roll the equipment and ask for souls and fuel, you can kinda read between the lines...
Just a FYI. Airflow over a wing can and does go forward in flight under certain conditions. Usually when close to stall speed or at a high Alpha.Point taken - a valid (but narrow) exception to my statements earlier. However, the purpose of my point was to respond to the assertion that a "tailwind" in normal flight somehow changes the direction or nature of airflow over the wing, related to that poster's speculation about a spoiler getting "locked" up.
I have some nice color footage of stall tests with a fully 'tuffted' wing which shows the air moving front to rear in cruise at 1.4 Vso, then as speed is slowly reduced, the airflow from the inboard trailing edge begins to go forward then progresses up to the leading edge and outboard until all wing lift is lost, as well as roll control. Technically, it's know as boundary layer separation.
I'm sorry, but a flight control issue can be very serious and you never know how it may develop. I'm glad this was much ado about nothing, professionally handled by the crew and controllers. Thanks for posting it!!Yeah, listening to this, I got the same chilled feeling as I got listening to the Alaska 261 audio (Jan, 2000; dove into the water off Pt. Mugu, CA due to horizontal stabilizer actuator problem.) First they reported a control problem, then they had thought all was OK and had it stabilized out. That much of the sequence was eerily similar between these two. Fortunately for the guys in UPS 2954, theirs stayed controllable, but boy, I just got a horrible feeling in my gut listening to it...
related to that poster's speculation about a spoiler getting "locked" up.
Wasn't speculation at all it happened...
That is now exactly what I am afraid about, when spoilers are active during a turn (roll) they disrupt the airflow to reduce lift on that side. When this disruptive airflow starts to rotate towards the backside of a spoiler (due to wingfoil) and lifts it up and into a locked position. So far only Airbus has had this and they have a exclusive wingshape (foil). So it has not (yet) been confirmed, but I am a litte afraid it would be possible. If this would be studied with a tailwind then I have no idea what will come out. (windtunnel vision)
Wasn't speculation at all it happened...
OK, I'm open to listening to evidence. I grant that spoilers disrupt airflow to reduce lift and this can be used to create rolling moments to initiate turns... But can you provide authoritative references or sources for any of the rest of the following:That is now exactly what I am afraid about, when spoilers are active during a turn (roll) they disrupt the airflow to reduce lift on that side. When this disruptive airflow starts to rotate towards the backside of a spoiler (due to wingfoil) and lifts it up and into a locked position. So far only Airbus has had this and they have a exclusive wingshape (foil). So it has not (yet) been confirmed, but I am a litte afraid it would be possible. If this would be studied with a tailwind then I have no idea what will come out. (windtunnel vision)