Caution wake turbulence

[Tim Krajcar]

I was reading in Bob Gardner's excellent "Complete Private Pilot" over the weekend about wake turbulence. Being a former VATSIM controller I knew about issuing turbulence and where I fly in the real world (KHIO) we occasionally have large business jets to wait for as well, but I thought this video was an absolutely excellent illustration of real world wake vortices...

Hat-tip to PE controller Kevin Meyers for this one

Here's the video on YouTube.

[Steven Winslow]

Awesome video! Thanks for sharing!

[Steve Anderson]

Wake turbulance kills. I live in Vancouver and a recent accident on July 9, 2009, at CYVR explains the danger of wake turbulance on approach. A Piper Chieftain APEX 511 was given clearance to enter a visual final for runway 25 Right 1.5 nautical miles behind and 700 feet below the flight path of a heavier Airbus A321. The circumstances of the accident are summarized by the Transportation Safety Board of Canada as follows:

"After crossing the VOR, APEX 511 descended to 1000 feet asl. At 2203, APEX 511 was advised that it would be number 3 behind an Airbus. The airport controller instructed APEX 511 to widen its approach to the east, downwind and issued a wake turbulence cautionary, including the position of the aircraft it was to follow. The crew of APEX 511 queried the airport controller as to whether they should do a 360° turn. The airport controller confirmed to widen its approach to the east and follow the traffic when in sight. At 2204, the airport controller pointed out the traffic on final approach, 6.5 nm away and descending through 3000 feet asl. APEX 511 reported the traffic in sight. APEX 511 was then instructed to follow that traffic, but not too far behind, as another Airbus flight was 8 nm from the preceding Airbus. APEX 511 was again cautioned about wake turbulence. The crew indicated that they would keep it in tight. This was the last communication from APEX 511."

The Piper Chieftain APEX 511 crashed 3 miles from the runway killing both pilots.

The TSBC concluded the accident was caused by wake turbulance from the preceeding Airbus A321 and blamed it on pilot error because the Piper Chieftain APEX 511 followed too closely behind the preceeding Airbus and below its flight path. They did not blame the CYVR air traffic controller(s) as visual separation was accepted by the pilot of Piper Chieftain APEX 511 and a wake turbulance caution was given. However the TSBC did note in their report that under IFR conditions air traffic control must maintain a 4 nautical mile separation between aircraft on final. They also noted that the current wake turbulence separation standards may be inadequate and visual separation may not be an adequate defence to ensure that appropriate spacing for wake turbulence can be established or maintained, particularly in darkness.

In my opinion if 4 nautical mile spacing between aircraft is required as a safety precaution under IFR conditions, why should it be any different for visual separation?

The full report can be found here: http://www.tsb.gc.ca/eng/rapports-repor ... asp#sec4.0

Sadly on October 27, 2011, a Beechcraft King Air 100 approximately 300 feet above ground and 0.4 miles from the CYVR runway, suddenly banked left and pitched nose-down. It then collided with the ground, and caught fire before coming to rest on an arterial roadway just outside the CYVR perimeter. Both pilots were killed and the passengers suffered severe burns and injuries. The crash remains under investigation. Although there is concern in this case of a mechanical failure, it would not surprise me in the least that wake turbulance was the cause or a significant factor in the accident. A preliminary report can be found here:

http://www.tsb.gc.ca/eng/medias-media/p ... 120209.asp

[Keith Smith]

My favorites from years ago:
http://www.youtube.com/watch?v=uy0hgG2pkUs (C-5)
http://www.youtube.com/watch?v=E1ESmvyAmOs

[Steve Anderson]

In its investigation report on the Piper Chieftain APEX 511 crash at CYVR, the TSBC noted the findings from the NASA tests on your YouTube links Keith, and stated:
"NASA conducted a series of flight tests to investigate the vortex wake characteristics behind a Boeing 727-200 during instrument landing system (ILS) approaches. A Lear Jet LR-23 and a Piper PA-30 Twin Comanche were used to intentionally encounter the wake vortices. A conclusion of the tests indicated that 4.5 nm would be a minimum separation distance at which roll control could be maintained by a small aircraft during a parallel encounter with the wake turbulence of the B727 in landing configuration." How can ATC or the regulations ever permit aircraft separation of less than 4 miles on approach, particularly at class C or B airports?