Cessna 120, Helicopter wake turbulence

[treadigraph]

Happened in January, very lucky escape for pilot who not only survived but seems to been uninjured, at least no mention of anything. Popped up on Blancoliro YouTube channel...

https://youtu.be/tZLXMKMgnS8

https://aviation-safety.net/wikibase/273729

[TowerDog]

Damn.....:ooh:

[Jhieminga]

That's pretty graphic.... I know two pilots who got caught in a helicopter's wake turbulence and ended up with some severe bruises and cuts. This footage clearly shows what happened and why you should leave more distance between yourself and a helicopter!

[UV]

What type of helo was it? Didn’t look large.

I have seen an Instructor taking off behind a landing Air Ambulance Agusta 169, less than seconds after it cleared the runway.....yes an Instructor. Even warned by the A/G operator.

[treadigraph]

Bell 205 or 212 by the looks of it. Probably an ex US Army UH-1.

[Jhieminga]

Over 4000 kg MTOW, not a light helicopter.

[punkalouver]

Reminds me of going around in a Tiger Moth on final many years ago to avoid the path of a helicopter that crossed in front of me. One never knows what would have happened if I didn’t but it makes me feel better that I did do it even though it might have been a smaller chopper.

[megan]

Tis a Bell 212, max gross 11,200 pounds.

[DaveReidUK]

The NTSB report (https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/104480/pdf) mentions the presence of two helicopters ahead of the C120, one of them crossing the runway. It's not clear which of the helos' downwash caused the upset.

Incidentally, the B212 visible in the video appears to be one of the San Bernardino County Sheriff's aircraft, based at KSBD.

https://cimg0.ibsrv.net/gimg/pprune.org-vbulletin/320x218/n307sb_76eb7b4e92a2c2ebe32d83908e282031585508b9.jpg

N307SB | Bell 212 | United States - San Bernardino County Sheriff | Martin Ma | JetPhotos (https://www.jetphotos.com/photo/10510367)

[JEM60]

Seem to remember several years ago that an Instructor and pupil were killed at Kidlington? when taking off near a helicopter that was doing a hot refuel in their vicinity. It rolled inverted on take-off I believe.

[treadigraph]

Probably this one (https://assets.publishing.service.gov.uk/media/5422f94de5274a13140006ed/1-1993_G-BPJT.pdf), JEM60, landing PA-28 encountered turbulence from an S-61N hover-taxying near the runway at Kidlington.

About 30 years ago I was sitting in the back of a PA-28 at Shoreham doing something or other while the pilot and other front-seater, also a PPL, did the walk round. A JetRanger hover-taxied along the taxiway at maybe 30' high and 50 - 100' to the right. The aircraft rocked in the downdraft and the door which was partly open flew open to the limit of the stay with a bang. Mein pilots boarded, closed the door and we taxied round to the fuel pumps. Couldn't open the door... The refueler managed to open it from the outside and we taxied back to get an engineer with a screwdriver. Broken split pin somewhere in the gubbins as a result of that blow. Gave me a healthy respect for helicopter wake - can you imagine if we'd crashed or ditched and had difficulties getting out...

[ShyTorque]

I’ve often been concerned how little consideration some pilots (fixed wing and rotary) give to downwash.

A few years ago I watched a certain pilot in a Squirrel hover taxy directly over a row of parked helicopters at Ascot. This resulted in the main rotor blade of a parked Bell 222 being blown sharply downwards to the extent that it damaged both the tail rotor driveshaft cowling and the driveshaft itself, causing the aircraft to be grounded. I sought out the 222 pilot and advised him of the event. The Squirrel pilot apparently denied all responsibility but hopefully learned his lesson.

Another time I watched another young CPL hover taxy another Squirrel right over the starboard wing of a Cessna 150 waiting at the narrow exit of the apron, causing the ailerons and elevators to blow about. If he had waited two minutes, off to one side, the Cessna pilot could have exited and let him in unhindered. I spoke to said pilot shortly afterwards. He seemed arrogant and totally dismissive of the event. I explained that it was a training aircraft and could have been flown by a very low hours student. If the flying controls had hit their stops and been damaged, it could easily have caused a serious accident. The pilot then said it was ATC’s fault because they had told him to taxy in!

On another occasion I was refuelling a SK-76 on the heli refuel point at Rochester. A light aircraft with two occupants taxied up not more than about ten yards behind and off to one side, parked up and they began to leave. I asked if they were coming back, because we were about to depart, to which I was told that they were leaving for the day. I pointed out that I couldn’t ground taxy on the wet grass and would have to lift to the hover and because they hadn’t tied their aircraft down I was concerned that our downwash would possibly lift it. We would be at near max gross weight (5 tons). I received a surprisingly very grumpy response from what was obviously an instructor, as if I was totally ruining their day. However they did go back and use the tie down points below the wings that they hadn’t otherwise seen the need for.

[Pilot DAR]

I too have watched a poorly though out hover taxi in an AS350, which resulted in damage to three parked and chocked Cessnas (enough downwash will blow a light plane over it's chocks). During the solo cross country phase of my helicopter training, I was cleared by ATC to land on an open pad. Either side of it was parked an R44, whose blades were not secure. The sloped surface away from the pad afforded me no other suitable landing area. So I instructed ATC that I would hover and wait for someone to secure the R44's blades. Eventually a person came out and secured the blades.

The effect of wake turbulence can be massive to light airplanes, and assumptions should never be made!

[punkalouver]

A good lesson in the above stories for newbies. Like the rest of society, there is a percentage of pilots that are jerks, make mistakes then deny wrongdoing, do stupid things, are inconsiderate, etc. That is why you need to be cautious. Locking your flight controls while parked would be a good example, as you can't be 100% sure some helicopter or other airplane won't come along and airblast your aircraft.

[meleagertoo]

I can't help wondering if the surprisingly high taxi-height of that (fairly heavy) helo didn't exacerbate the problem. Wouldn't a steeper and more conventionally angled approach to a proper hover-taxi height leave much less turbulence that swanning around at fifty feet and thirty knots?
Bear in mind this wasn't pure downwash effect as described in the several incidents above but genuine disk-induced free-air turbulence which will be approaching its max as power is markedly increased in a decelerative attitude approachng the loss of translational lift. At ground level that'll just spread out horizontally - up there at treetop height and more it'll swirl and persist for quite a while, as the poor unsuspecting Cessna pilot found out.

[Pilot DAR]

poor unsuspecting Cessna pilot

He/she should have been suspecting.....

[Jhieminga]

He was, he was carrying out a go-around at the time. The pilot wrote up a detailed report about this accident, click here to read the PDF (https://s30121.pcdn.co/wp-content/uploads/2022/07/Cable-Pilot-Report.pdf). In contrast the NTSB report is pretty succinct, click here to see a PDF of this document (https://s30121.pcdn.co/wp-content/uploads/2022/07/Cable-Accident-Report.pdf) (it is also copied in to the Pilot's report). Both documents from AvWeb's post about this accident (https://www.avweb.com/insider/is-better-to-be-lucky-or-good-yes/) (also worth a read).

[RatherBeFlying]

I remember landing a Citabria with one or Schweizer trainers doing hover practice 150' off to the side. Plenty of wake turbulence from even small helicopters.

[Maoraigh1]

In that situation, would a non-standard go-around, to avoid helicopter wake, be appropriate? Notifying ATC or broadcasting on unicom.

[172_driver]

In that situation, would a non-standard go-around, to avoid helicopter wake, be appropriate? Notifying ATC or broadcasting on unicom.

Sounds like a good idea.

At John-Wayne Orange Country airport ATC used to clear us - in a C172 - for take-off right after a B757 or A300 lifted off at the other end of the runway. So it used to be a climb to 50 ft and then a 20-30 deg change of heading. There was a small twin that went down on its back there in 90s after a wake encounter, killing the CEO (or founder?) of In'n Out Burger, iirc.

[C152_driver]

Years ago I was doing solo consolidation circuits at RAF Henlow in a 152 when I heard two Chinooks call inbound for a touch and go. I had a sudden attack of trepid and made the next landing a full stop. Seeing this video convinces me that was a good call.