> one thousand feet above Are the imperial units of measurement an aviation thing, or an American thing, or a bit of both?
In aviation, altitudes are in feet, distances in nautical miles, speed in knots (nautical miles per hour).
Enroute Airbus A380 wake flips Challenger business jet upside down
21–30 of 376 posts
Re: Enroute Airbus A380 wake flips Challenger business jet upside down
#22For anyone interested, there are several great youtube videos[1-4] that show the wakes (the wingtip vortices in particular) created by various aircraft. This incident brings the Reduced Vertical Separation Minima (RVSM)[5] into question. Strategic Lateral Offset Procedure (SLOP)[6] can be used used to avoid such incidents. [1] https://www.youtube.com/watch?v=E1ESmvyAmOs [2] https://www.youtube.com/watch?v=dfY5ZQDzC5s…
Those wingtip and flap effects on 2 are gnarly! I assume that those occur near dewpoint? or some other atmospheric conditions?
Re: Enroute Airbus A380 wake flips Challenger business jet upside down
#23> one thousand feet above Are the imperial units of measurement an aviation thing, or an American thing, or a bit of both?
Aviation. 500 & 1000 ft intervals are very convenient discrete altitude levels for coordinating traffic, and that's probably a key reason why it's held up universally. In meters, the interval will either awkward and hard to communicate numbers or spaced too widely to be efficient.
I think the reasons are historical, because the U.S. pretty much invented the industry.
I believe the eastern block used to use meters, I doubt 300m was much more difficult to deal with mentally than 1000 feet!
Re: Enroute Airbus A380 wake flips Challenger business jet upside down
#24I don't know much about aviation, but 1000ft seems kinda close to pass another aircraft. How normal is that distance?
It's fairly standard practice, as long as the aircraft involved are certified for it and flying on autopilot. Given that the planes involved were flying at FL350-60, they probably were (altitudes above a certain threshold - FL290 in the US) are restricted to aircraft operating under rules allowing 1000ft vertical separation.
https://en.wikipedia.org/wiki/Reduced_vertical_separation_mi...
Re: Enroute Airbus A380 wake flips Challenger business jet upside down
#25The physics of this are insane. Then again, by my calculation the A380 displaces roughly 11 million cubic feet of air per second at the max landing weight.
Why does the landing weight effect the air it displaces?
Weight of airplane = mass of air displaced per second * velocity of air.
The weight of the airplane is a force downward, the air must match that force, either by throwing a lot of air with little velocity, or a less air, faster.
Re: Enroute Airbus A380 wake flips Challenger business jet upside down
#26I don't know much about aviation, but 1000ft seems kinda close to pass another aircraft. How normal is that distance?
By law, 5 (nautical) miles horizontal separation or 1000 feet vertical separation is required. When aircraft were smaller, that was probably more than sufficient. The A380 is another beast entirely, though.
Re: Enroute Airbus A380 wake flips Challenger business jet upside down
#27> one thousand feet above Are the imperial units of measurement an aviation thing, or an American thing, or a bit of both?
Aviation thing (unfortunately, but it is what it is). You'll hear them referred to as Flight Levels or Angels as well (Angel 15 == 15,000feet).
Technically, the lowest flight level is FL200 or 20000'. Below that, altitudes are reported in feet. I'm not really familiar with the "angels" thing. I suspect that is specifically military.
EDIT: there was a reply (since deleted) that indicated I may not be completely correct on stating FL200 as the lowest number used. I contend that I am still basically correct for North America, but there is some subtlety:
Re: Enroute Airbus A380 wake flips Challenger business jet upside down
#28For anyone interested, there are several great youtube videos[1-4] that show the wakes (the wingtip vortices in particular) created by various aircraft. This incident brings the Reduced Vertical Separation Minima (RVSM)[5] into question. Strategic Lateral Offset Procedure (SLOP)[6] can be used used to avoid such incidents. [1] https://www.youtube.com/watch?v=E1ESmvyAmOs [2] https://www.youtube.com/watch?v=dfY5ZQDzC5s…
Those wingtip and flap effects on 2 are gnarly! I assume that those occur near dewpoint? or some other atmospheric conditions?
They always occur. It's just that around the dewpoint you can visualize them. But they're all the more deadly for normally being invisible.
Re: Enroute Airbus A380 wake flips Challenger business jet upside down
#29For anyone interested, there are several great youtube videos[1-4] that show the wakes (the wingtip vortices in particular) created by various aircraft. This incident brings the Reduced Vertical Separation Minima (RVSM)[5] into question. Strategic Lateral Offset Procedure (SLOP)[6] can be used used to avoid such incidents. [1] https://www.youtube.com/watch?v=E1ESmvyAmOs [2] https://www.youtube.com/watch?v=dfY5ZQDzC5s…
Those wingtip and flap effects on 2 are gnarly! I assume that those occur near dewpoint? or some other atmospheric conditions?
To add to jacquesm's response, the footage in [2] is definitely from a humid day. That makes condensation happen very readily.
If I remember correctly, the trails from the outboard edges of the flaps are just like wingtip vortices. The airfoil's geometry suddenly changes, acting like a wingtip and creating a vortex.
Re: Enroute Airbus A380 wake flips Challenger business jet upside down
#30Had to google around to understand wake turbulence. If I read the wiki correctly, it's basically a horizontal tornado that emanates from the wings. That would explain the rolling that the aircraft encountered.
On another note, I fly every week for work, can't imagine rolling five times and engines losing power with a drop of 10k feet. That's absolutely insane. I've had engines lose power before, but it was quickly regained such that the drop was more moderate.