'Wake turbulence' probed in crash of Flight 587

CNN ^ | 11-13-01

[dogbyte12]

NEW YORK (CNN) -- Federal investigators said they are considering whether "wake turbulence" from another airplane may have played a role in the crash of a commercial jet that crashed Monday, scattering debris over a Queens neighborhood and claiming more than 260 lives.

[Cleburne]

Air turbulence can rend a plane to pieces?!? Uh, that don't really fly with me (groan).

[southland]

Why do so many airplanes fall out of the sky at JFK??

[southland]

Wake turbulance can be very profound under certain conditions. As a former Air Force Pilot and former Air traffic controller it does seem that 6 miles would be sufficient distance to dissipate the turbulance of that magnitude. I have made a 360 degree turn in a B 36 (10) engines and hit my own wake turbulance but it was not sufficient to cause any problems like the AA flight experienced,

[justlurking]

Ten seconds later - when flight 587 has been aloft 114 seconds -- the pilot is heard commenting on encountering a "wake effect."

Local Fox News in NY is reporting the "wake effect" comment on the tape, although they call it "wake turbulence".

There are a couple of problems, as has been noted in this thread. The preceding plane was beyond the safe following distance used by air traffic control. Wake vortices tend to sink down and out, although prevailing winds will alter their "trajectory".

Standard procedure when following a heavy aircraft is to rotate and takeoff before the rotation point of the heavy aircraft, and then climb to remain above the heavy's flight path. However, wake turbulence is typically most dangerous to light(er) aircraft following the heavier aircraft. An A300 is a jumbo jet itself, although not quite as big as a 747. Frankly, I don't think an A300 would be dangerously affected by wake turbulence, unless very close to the ground or something was already wrong.

I wonder if something else happened on the airplane that caused a rough pitch/yaw/roll motion and the pilot's first instinctive reaction was to identify it as wake turbulence, especially since the tower's last instruction with their takeoff clearance would be "Caution, wake turbulence" after the preceding departure of the 747. The manifestation of wake turbulence is not necessarily distinguishable from other causes.

[Clinton's a rapist]

I wonder if something else happened on the airplane that caused a rough pitch/yaw/roll motion

Like the tail falling off, maybe?

Good suggestion.

[Hazzardgate]

During the summer I saw an A&E Bill Kurtis scare documentry about "wake Vortex". It had a bunch of scared looking ex-FAA people swearing that "wake Vortex" would take down a passenger plane in USA sooner than later. Actually, just like the terrorist experts were saying about attacks on America.....

[Map Kernow]

You know, why doesn't the government just say it was the Big Bad Wolf that huffed and puffed, and he BLEW THE PLANE APART!!!

I mean, they've been treating us all like we're children ever since that flight went down anyway....

[TC Rider]

From the Aviation Pics Site

[Lion's Cub]

Another trial balloon. They are trying to find something that will hold up under scrutiny.

Blame CNN, not the NTSB for this one. I missed the 8pm briefing, but I saw some the one just before that--in which they talked about the wake, the rattles, etc. The spokespersons seemed pretty straightforward to me, and didn't seem to be trying to float any trial balloons at all.

When briefing the press on the contents of the cockpit voice recorder, they mentioned that the pilot made a reference to wake encounter. The press then jumped on it. The spokespersons said that they knew a JAL 400 had taken off before 587, but that they didn't yet have any more details than that. It's the press that is making a big deal out of the wake theory, not the NTSB.

[justlurking]

During the summer I saw an A&E Bill Kurtis scare documentry about "wake Vortex". It had a bunch of scared looking ex-FAA people swearing that "wake Vortex" would take down a passenger plane in USA sooner than later.

It's a very real possibility and that's the reason for the wake-avoidance procedures. But, the passenger planes in danger are the small commuter turboprops and regional jets. Unless several people really screw up in succession, an A300 is not going to be in trouble.

On takeoff, planes are flying at or below "maneuvering speed", where the airplane wing will stall before it is stressed beyond the breaking point. Wake turbulence is dangerous because it most typically is encountered near the ground, where a plane doesn't have enough altitude to recover from any unusual attitude that may result. -- not because it might break something off.

[Stefan Stackhouse]

Wake turbulance can be very profound under certain conditions. As a former Air Force Pilot and former Air traffic controller it does seem that 6 miles would be sufficient distance to dissipate the turbulance of that magnitude. I have made a 360 degree turn in a B 36 (10) engines and hit my own wake turbulance but it was not sufficient to cause any problems like the AA flight experienced,

If wake turbulance is a phenomena that is this well known, then there is absolutely ZERO excuse for conducting flight operations that fail to minimize the problem to the greatest possible extent.

Sorry, but offering wake turbulance as the explanation for this crash will NOT reassure the traveling public. I'll be buying plane tickets again once the airline industry gets its act together, not before.

My guess is that this "explanation" will quickly be relegated to the dustbin of history.

[ladyinred]

ooooooo!

[Stefan Stackhouse]

Post #29:

Exhibit "A" in my assertion that wake turbulence has been scientifically studied to a sufficient extent to allow flight operations to be conducted in a manner that will avoid the danger. There is simply no excuse for this even being a possibility.

[Clinton's a rapist]

But, the passenger planes in danger are the small commuter turboprops and regional jets.

Right, so the prior probability that the first ever case of an airliner being downed by wake turbulance will be a Jumbo jet is...about the same as that the first case of inhalation anthrax in 25 years will occur less than a mile away from Mohammed Atta's favorite airfield.

[ladyinred]

Oh my gosh, I am just loving your remark!
The trouble is they probably will see it and think, "hmm, maybe we can use that one sometime!" :) LOL. too funny!

[kylaka]

The flight data recorder will tell the tale... the whole tale. It will record the loss of power, and loss of hydraulics causing any yaw or roll, when the tail separated and exactly what pitch and yaw changes that caused.

Wake turbulence is unlikely. The 747 was 8 miles ahead. That the pilots mentioned it only means they had an uncontrolable roll but had not yet identified a source. That the vertical stabilizer landed in Jamacia Bay, and the engines landed on land, not distant from the main wreckage is signifigant. The engines separated late in the sequence of events. The eyewitness reports that an engine separated and knocked the tail off is totally bogus. The stabilizer separation caused the crash. What caused it to go, is the mystery.

[Young Werther]

In the early 70s a B-52 was studying clear air turbulence while flying near Colorado Springs where this type of weather turbulence can occur. Results-it lost its vertical stablizer. The crew was able to steer the aircraft using differential thrust on it outboard engines. With eight engines this is an "easy maneuver" since you are tweaking an engine with 12-15 thousand lbs of thrust. The A-300 has two engines with over 75,000lbs of thrust and over control is an issue.

I was in SAC, (a ground pounder but with an altitude chamber ride so I liked to hitch rides on training flights) one day I participated in a MITO, (minimum interval take off) an EWO scramble where there was 30 second separation between bombers. We were # 2 and I can assure you the wake turbulence was somethin' else!!! WE rotated and bounced up over two hundred feet. I was "guarding" the throttles and was to apply full thrust if the pilot ordered it. The pilot wanted both his hands on the wheel along with those of the copilot.

If the aircrew experienced this difficulty well maybe just...we should wait for the forensics

[justlurking]

If wake turbulance is a phenomena that is this well known, then there is absolutely ZERO excuse for conducting flight operations that fail to minimize the problem to the greatest possible extent.

You are correct, and flight operations are conducted in a way to do so. From what has been described in this thread, those procedures were followed.

Since I didn't see the NTSB briefing, I'll have to yield to the person that commented that CNN and the rest of the media have "seized" the wake turbulence issue to boost their ratings. Frankly, I think it was probably little more than an instinctive instance assessment by the pilot.

I believe it will turn out that the failure simply manifested it in a way that was mistaken for turbulence -- presuming that the NTSB doesn't latch onto it to avoid a more embarrassing explanation.