Blackhawk wake flips Cirrus

bc2209

Well-Known Member
Not sure if this has been posted or not but it's the most fascinating, impacting, scary video that I've seen regarding wake turbulence.

This is a huge eye opener and teaching tool as well.


"The pilot in this video was not hurt critically; he had some scrapes and bruises, was shook up, but basically came out of it in good condition. I spoke with him yesterday and he was happy to share his experience for the good of safety. This event took place at a non-controlled airport.

In the video, you can see that a Cirrus SR-20G2 aircraft was flipped on final by a Blackhawk helicopter’s downwash. The pilot of the Cirrus said that as soon as he realized that he was in turbulence he went to full power with ailerons and rudder full right, but to no avail, the turbulence forced him over and the wing tip struck the runway.

The Cirrus was on left downwind, heading South and about to turn base for a full stop landing, the helicopter was on the numbers. The helicopter pilot departed to the North, he also side-stepped to the parallel taxiway to get out of the fix-wing’s way. The winds were about 3kts at the time. What is truly remarkable is that the event happened ~28 seconds after the helicopter departed (the turbulence was still there).

While speaking with the pilot of the Cirrus he said that there was another similar incident a few years ago here in Colorado, he is sending me info on that and I will pass it on as well. In that situation a very high time Air Force Instructor pilot departed in a Diamond 20 and encountered the same issue, only it was ~75 seconds after the Black hawk had departed and was at 40ft on departure. I believe both in the Diamond were ok then as well.

Please pass this video on to others and discuss it with your students and fellow pilots."

This was taken from an acquaintance of mine who posted of Facebook.
 
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Pretty startling stuff.

Happened to this pilot last year:

http://www.ladieslovetaildraggers.com/blog/karen-croskell-blackhawk-rotor-wash/

I look at the various safety seminar given by the FAA from time to time and it seems they have had a number of these incidents in Colorado and in other states near bases where heavy choppers fly around/from and they have been having safety seminars just to address this issue. They held one just two weeks ago in Englewood.
 
Heavy helicopter rotor wash/wake is no different than that of heavy fixed-wing aircraft, especially in light to no-wind conditions. Similar precautions need to be taken when observing these RW aircraft departing/arriving.
 
I didn't remember ever hearing anything about helicopter rotor wash in my primary training. Didn't even realize they produced a wake until I flew below and behind a USCG helo inbound to the airport once. That cleared it up for me.
 
I didn't remember ever hearing anything about helicopter rotor wash in my primary training. Didn't even realize they produced a wake until I flew below and behind a USCG helo inbound to the airport once. That cleared it up for me.


Does anyone read the AIM or does any CFI teach out of it anymore? Seriously. The information is there, in black and white. The AIM has a ton of good info. Pilots just have to have the initiative to crack it open to see. (italics in paragraph are mine)


Section 3: Wake Turbulence

7-3-7

Helicopters

In a slow hover taxi or stationary hover near the surface, helicopter main rotor(s) generate downwash producing high velocity outwash vortices to a distance approximately three times the diameter of the rotor. When rotor downwash hits the surface, the resulting outwash vortices have behavioral characteristics similar to wing tip vortices produced by fixed wing aircraft. However, the vortex circulation is outward, upward, around, and away from the main rotor(s) in all directions. Pilots of small aircraft should avoid operating within three rotor diameters of any helicopter in a slow hover taxi or stationary hover. In forward flight, departing or landing helicopters produce a pair of strong, high-speed trailing vortices similar to wing tip vortices of larger fixed wing aircraft. Pilots of small aircraft should use caution when operating behind or crossing behind landing and departing helicopters.
 
Never even given this thought, nor ever heard a pilot talk about rotor wash. Thanks for sharing, good to know.
 
Never even given this thought, nor ever heard a pilot talk about rotor wash. Thanks for sharing, good to know.

It's certainly not some new phenomenon previously unknown or something hidden away in an obscure publication. Why its not being taught to pilots, or why many don't seem to be aware, is somewhat startling in terms of training or even self-study continuing education for pilots.
 
Never even given this thought, nor ever heard a pilot talk about rotor wash. Thanks for sharing, good to know.
I've heard military guys say "caution rotor wash" or had a controller say it to me once or twice when it was a big helicopter, but that's been maybe once or twice. I know my company had an elevator get damaged when rotor washed slammed it around while it was parked without a gust lock. Wouldn't have been pretty if they hadn't caught it on the preflight.
 
I've heard military guys say "caution rotor wash" or had a controller say it to me once or twice when it was a big helicopter, but that's been maybe once or twice. I know my company had an elevator get damaged when rotor washed slammed it around while it was parked without a gust lock. Wouldn't have been pretty if they hadn't caught it on the preflight.

The responsibility goes both ways. Where pilots of light fixed wing should try to avoid taxiing near or operating around hovering or hover-taxiing helos, especially heavy ones, and should take other precautions; the crews of helos should take reasonable precautions to avoid hover taxiing near light planes etc. That's why most helos with wheels, primarly heavy helos, land on taxiways or runways/runway intersections, and then just ground taxi in to parking. That way with their blades at mostly flat pitch, there isn't any harsh down/outflow to damage parked or taxiing aircraft.

Similarly, skid helos can also taxi with extremely low hover heights to minimize their outflow if going in/out of ramp areas that are close to parked light aircraft. I do this all the time when hover taxiing....about 1-2 AGL skid height, and sometimes accidentally dragging a skid heel (no issue with that). This is done to minimize rotor wash, as well as be able to successfully perform a hovering auto should the engine fail, without damaging the helo by hovering too high with very slow forward speed. (outside the front part of the height/velocity chart).
 
Mike, what does the Aibus helicopter height/velocity diagram look like?

The -67 we could safely, and routinely auto'd from a 10' hover. I think our issues started around 30'.
 
Oh yeah, obviously the height/velocity chart.

Being outside the front of that chart can have consequences where you hovering too high and too slow to successfuly autorotate were an engine to fail, without running out of rotor speed first. And in some helicopters with low-inertia rotor systems, about 8 feet or so is the highest you can slowly hover taxi safely with regards to this.
 
Mike, what does the Aibus helicopter height/velocity diagram look like?

The -67 we could safely, and routinely auto'd from a 10' hover. I think our issues started around 30'.

Like I mentioned, about 8' or so is safe enough to not spread the skids, when hovering below ETL. Further above that, you'll run out of collective quick. I'd have to look at the H/V again in the manual to get the exact numbers for the heights, but those are the ballpark. Being that I hover-taxi around at 1-2 feet, I've never paid a ton of attention.
 
Being outside the front of that chart can have consequences where you hovering too high and too slow to successfuly autorotate were an engine to fail, without running out of rotor speed first. And in some helicopters with low-inertia rotor systems, about 8 feet or so is the highest you can slowly hover taxi safely with regards to this.
I figured it was something like that, but you said it so mater of fact like us fixed wing guys knew thats what it was.... I thought it was funny.
 
I completely forgot about the difference between semi-rigid and full articulated rotors.

I can see why the H/V is so low now.

Currently, as you know, IPAC does all the thinking for me. It spits out a min airspeed/ based on OGE.
 
I vaguely remember it from ground school and whatnot. I had an exemplary instructor warn/brief while we were doing pattern work at KIWA Mesa-Gateway.

I've also run into Apache's and even once an Air Crane at Falcon, ASTARS at Marana, Blackhawk (If I remember correctly) at Ryan,

Fraking Arizona and them helicopters.

Actually I love them but will be avoiding and cognizant as •.
 
Mike, what does the Aibus helicopter height/velocity diagram look like?

The -67 we could safely, and routinely auto'd from a 10' hover. I think our issues started around 30'.

Ok, so here's for the AS350B3 version. 5-10 knots nominal hover taxi speed.

b3.png
 
I had no idea how bad the rotor "swirlies" were till my first time follwing H-60 on practice PAR into KNZY in a Metro at max gross and we still went for a bit of a ride. Those things are no joke especially for SE pistons.

Glad my fellow chute-puller is okay and walked away.
 
I had no idea how bad the rotor "swirlies" were till my first time follwing H-60 on practice PAR into KNZY in a Metro at max gross and we still went for a bit of a ride. Those things are no joke especially for SE pistons.

Glad my fellow chute-puller is okay and walked away.

That's why I say to pilots crack open the AIM. Lots of good info in there including this and much more. The AIM is the complement to the FARs, both of which carry a Biblical sense for pilots. And with something like this subject it's better to learn about it the easy way rather than the hard way.
 
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