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ViperSocks

A question for the helicopter pilots out there... did he run out of tail rotor (rudder) authority?


nosecohn

Yeah, I too am wondering what exactly happened here. The clothing of those waiting doesn't seem to be moving too much, so I'm not sure if this was a wind-related thing or a mechanical issue.


StrugglesTheClown

Checking online they are at around 12,500 feet so I'm guessing that was also a factor.


Columbu45

This, reduced tail rotor authority at high DA, not sure where winds were at in this scenario but even a slight tailwind, could create a situation like this. Usually the answer more airspeed, reducing the load on the tail for Antitorque. Also like someone else said. Full pedal in the opposite direction of the spin, not kinda full pedal, all the way to the stop.


d3agl3uk

In motor racing you can use air (vortices etc) to block other paths of air. It looks like it happened when they got lower to the ground. Could air reflecting off of the ground restricted the efficiency of the tail rotor? I ask in complete ignorance. Just curious.


pinchhitter4number1

Generally, no. Close to the ground that air "bouncing" of the ground provides a cushion and allows the aircraft to hover with less power demands. It's called being in ground effect (IGE). However, in the mountains plus with the transition over the edge of the landing pad winds can do weird things. They are at high altitude and higher weights (6 pax with baggage) and out of ground effect (OGE), this all adds up to a high power requirement and a lot of left peddle needed (with a main rotor that turns counterclockwise). They likely ran out of left peddle or delayed too long in pushing full left peddle and the right yaw was unrecoverable. No matter what, the pilot did a great job getting everyone safe on the ground.


carnivorouz

I got gigged on this for my checkride, so I'll pass it along. It's not actually a "cushion" from the vortices bouncing back up but rather the ground is allowing those vortices to be pushed outwards, resulting in greater efficiency from the rotor system and increased lift.


fighterace00

Depends which physicist you talk to that day


d3agl3uk

Alright thank you!


GlockAF

Skill plus luck


KinksAreForKeds

I remember a very similar-looking situation happening on Mt Hood here in Oregon a number of years ago, as a NG chopper was trying to rescue some skiers at 11,000'. We could watch the whole thing from our porch. Unfortunately that didn't end as well.


CrashSlow

The short answer is yes. I'll try and explain what probably happened. It's complicated as swapping ends like this could be combinations of things. Altitude, down wind, power available, over weight for density altitude. I have no idea how this guy didn't turn into a ball. It's possible to run out of engine power and that will cause lack of TR authority. The engine hits max N1 or fuel flow and the rotor rpm droops, tail rotor thrust drops. Then the heli swaps ends. If you reduce power the rotor RPM should recover, but thats hard to do when the ground is rushing up, most pilots just keeping pulling and making it worse. The tail rotor can only produce so much thrust, some heli's have better tail rotors than others capable of more thrust. It is possible to aerodynamically stall the tail rotor but its is very misunderstood in the heli world. Reducing power and putting in full pedal will usually stop it. Problem is you can get into what i wrote above and if this at altitude you can be power limited and in many of these LTE crashes the pilot didn't push the pedal to the stop. Once you start swapping ends fast enough the CofG vertical changes with the heli being top heavy and its game over.


the_silent_redditor

Fuck, how counter intuitive it would feel to reduce RPM when things are going insanely tits up and the ground is speeding up to aggressively say hello. It looks like this all came on really acutely. Would you get more of a sense of this happening if the pilot were to more gradually slow airspeed on approach to the landing zone? I imagine it’d be easier to ease down RPM if this were all more of a gradual process.


fivechickens

That first wiggle to the right was a pretty strong indicator to do a go-around or jam in a lot more pedal, but approaching into a bowl like that with a crowd of people in front of the pilot would be a huge mental block and they likely were facing a lot of distractions and wouldn’t have recognized. 12,500’ is a super high DA and with 6 people on board you’re asking a lot, especially if you’re slow on the pedals or wind is coming up your ass. I couldn’t find charts quick and I’m not rated on the Koala so I can’t say but marketing numbers seem to be 10,500’ Hover Out of Ground Effect (HOGE) with a 2800lbs useful load so that’s gonna be pretty thin or vanished margins if you’re asking to do that with 6 people and likely a bunch of baggage and enough fuel to get back for the next group.


CrashSlow

It's not really any different than an airplane and getting behind the aircraft or doing an unstable approach and trying to save it. In Mountain flying its best practice to set up the approach way back and get heli slowed down and pulling in power. If you're maxed on power and not arresting the decent rate, odds are you're going to run out of power to land. Two option, abort and since your a long way back you got altitude to get airspeed. Or fuck it, coming in hot and hope you can slide it on and get some in ground effect cushion. The second option usually leads to an over Torque / swapping ends, cause you're probably going to fuck it up. The fuel control is always trying to keep the rotor speed at 100%. Turbine heli's this is done automatically by the FADEC or hydro mechanically. The pilot only has to keep the engine within its limits. If you pull power beyond engine limits the rotor droops, reduce power the rotor RPM recovers to 100%.


FobbitOutsideTheWire

Username checks out. Lol


CrossfeedCow

Oddly enough if you’re extremely power limited but have the room like it looks like he might have had, the best option isn’t a long slow approach high up. Stay above ETL until you’re low and in ground effect and then slow down IGE. A lot more options with power availability and if you do lose tail rotor authority for any other reason, you can just do a hover auto or blend of quick stop and hover auto and get down without rotation.


fighterace00

Just like a t tail stall ie colgan air crash


0xSnib

This is why I stick to planes


horousavenger

And that place is at 12k ft


dmlrr

I was taught that IGE is less than one rotor diameter above the surface, this looks like more than one diameter. Wouldn't a safer approach be to use fly with forward speed into IGE? Or use the ground effect to recover? (easier said than done)


Billy_Goat_

Great read. And you please ELI5 the CofG vertical changes?


CrashSlow

Like everything with heli's is complicated. Helicopters are top heavy and when they start to rotate rapidly around mast it throughs that top heavy weight out sideways like its trying to role onto its side. Eventually you get to the point where the flight controls cant correct for this and it's pretty much game over. You can see this in some accidents when the rotations get high and it looks like airframe is leaned over to one side. Thats the dumb pilot version, don't let it rotate fast around the mast.


2Tall4U

Yes. It appears to be a classic case of LTE (loss of tail rotor effectiveness). While a stuck pedal or a mechanical issue could also be the cause, LTE is a serious risk when operating at high density altitudes, when heavy (they had full pax) and slow. They got very lucky with the orientation of their hard landing. Once LTE starts to develop a spin opposite the rotation of the main rotor will develop. Power demand/main rotor torque needs to be lowered quickly before an unrecoverable spin develops. Lowering the collective is the first option, shutting the engine down and performing a “hover auto” is the second less desirable option.


LupineChemist

I'm wondering since it looks like it's on the edge of the cliff if it was something like an updraft coming up off of the cliff having an effect and then having the other half be relatively calm so could be something like too little tail rotor on one side and so you compensate and then end up with too much once you're out of it.


Fentron3000

Looks like LTE, loss of tail-rotor effectiveness.


T-701D-CC

Yes that is classic LTE and a horrible job dealing with it from the pilot, he should have gotten some forward airspeed and gotten the fuck out of there before the spin developed


Advanced_Review_195

that is the factor. High,Hot,Heavy


Red_Kys_Zone

His Tail rotor servo had a failure , good quick thinking and reaction by the pilot saved all their lives


hubec

Yes, and utterly failed to properly deal with it. As his forward speed bled off he would have been adding power pedal until he hit the stop, at that point he should have begun returning to forward flight. And tried the approach again - this time decreasing forward speed below translational only when well in ground effect. This pilot did butt fuck nothing. Just sat there when the helicopter began spinning like a fucking idiot. Fuck this guy, he should have his license take away. Hell he should be prosecuted for endangering the lives of his passengers.


Future_List_6956

Aww, hell folks. You really don't have to run until the BIG chunks start coming at ya. 🙄


[deleted]

[удалено]


the_silent_redditor

> trying to put everything, and everyone, between me and potential incoming blades/spears of death Fuckin’ outta ma way, gramps _pushes elderly man to the floor_


[deleted]

[удалено]


Raguleader

"Gramps, wear this!" *throws an interceptor vest with ESAPI plates onto gramps*


BLeeS92031

Push him down? It's shrapnel, not a bear. That means you need a wall of meat, not a pile of it.


Phil-X-603

How did he land safely while doing a flat spin


muhmeinchut69

yeah and looks like he was still spinning after he touched the ground. EDIT: Here's a much better video from the other side. Looks absolutely mental https://twitter.com/AshTheWiz/status/1793890258733670867/video/1


BigmacSasquatch

Wild. That little bounce seemed to have kept them from digging in and flipping.


duggatron

Sometimes you just get lucky.


BigmacSasquatch

Did you catch the little flash of oil fire from the rotor hub after the bounce (~0:33)? It did NOT like that lol.


El_Fader

First thing I saw from that full angle was how incredibly casual that one guy who was sitting on where it landed walked away edit: I should say where it first touched down, it ended up quite a bit further away. Miraculous indeed


yousirnaime

Pilot is either really really really good - or really really really bad - and I'm too stupid to tell the difference


Coreysurfer

As were some of the people standing there, guess they never seen a copter crash and well scatter its bits everywhere..


LoudestHoward

That first video is mental, went about as well as you could expect. The guy down on the grass just slowly walking away seems to have no sense of self preservation.


CarbonGod

doubt he knew anything was wrong...just a helicopter and it's noise. Once it hit ground and he looked back, prob was like "eh, it landed...why there? whatever, i want tea"


brute313

Idk id argue it’s better to watch to figure out where the big blade skinny thing is actually going then *assume* you are running away from it.


LoudestHoward

Keeping an eye on the thing is good, but I take a leisurely walk to the shops with more urgency.


brentus

Seriously. Especially since it landed right where he was


KinksAreForKeds

Thank you! I was having trouble rectifying how you can clearly see the main rotor turn almost sideways and the rear mast pop up after it drops below the edge in OPs video. Just couldn't figure how it was still upright at the end. Definitely a crazy ride.


mebonesrattle

Good God I hate twitters video player!


CrashSlow

To the pilots surprise,,,,, the pedal could go further into the floor.


Swedzilla

Introducing the new 360 axle pedals lol


P1xelHunter78

Probably temporary loss of tail rotor effectiveness, I guess it actually happens. You’d have to ask a real chopper pilot how he made it work though


i_should_go_to_sleep

You can tell they tried to get forward airspeed and fly out of it but they waited way too long and the yawning rate was way too high. They didn’t make it work, they got lucky they didn’t roll over.


anal_og_player

Dude has 2 massive counterweights between his legs.


OmegaPoint6

Sheer dumb luck?


LoudestHoward

Maverick take notes!


[deleted]

Probably autorotation.


Ibegallofyourpardons

you do not autorotate from 50 feet while spinning.


[deleted]

He has to do something to decrease the main rotor torque in a hurry. Dropping the collective is one way to do that.


FighterJock412

Dropping the collective will also drop you like a rock. What you do, is roll off throttle rpm smoothly.


AlternateAccount789

He didn't drop the collective though, or the helicopter would've descended immediately. Instead, he kept the collective where it was for several seconds to try and control the spin before setting the helicopter down very slowly and methodically. That is not how a hover-auto works, not from that altitude at least. Engine failure also doesn't induce spinning like that.


[deleted]

That's more than 50 vertical feet. The ground slopes away from the cameral.


Remarkable_Ticket264

That definitely is not 50 feet, even over the slope. If you’ve flown an actual airplane you would know.


[deleted]

I've been a licensed pilot since 1988. That was probably before you were born.


Chairboy

Not enough 2-1 oil in the fetzser valve. There, I offered an explanation just as smart as yours.


NottDisgruntled

Always looks crazy when the copter blades sync with the camera like that. Also… run motherfuckers, run!!!! Godddddammn


MonkeyNumberTwelve

Yeah, I was saying similar to the screen. Having seen the aftermath of a few helicopter crashes IRL broken rotor blades are terrifying. There's another photo I've seen that one of my colleagues took of this incident with a 3 foot peice of rotor blade embedded in the bedroom wall of one of the houses in the background. https://www.walesonline.co.uk/lifestyle/nostalgia/day-helicopter-crashed-just-yards-25135568


MagPistoleiro

Yeah, they are no joke. I remember sticking my finger on the desk fan and my nail had an internal bleeding. Every time I see these accidents I think of this day, cause a dumb plastic little blade rotating did that to my finger. Imagine a giant fucking metal blade. Tha shit would cut you like cutting styrofoam using a glowing red wire.


superspeck

When the guys in high vis start running, you should be in front of them.


sad-mustache

This, freaked me out a little So many people and everyone just stands there


Lower_Discussion4897

Miraculous landing, I was waiting for bits of rotor to fly in all directions.


PotatoEatingHistory

A lot (in fact, almost all) of these civilian pilots flying the Kedarnath route used to be Indian Air Force pilots flying up to Siachen in Aloutte IIIs. They're the most qualified mountainous terrain helicopter pilots iirc. Still, that was one hell of a recovery


Vigi1an7e

Yeah siachen pioneers, my father was also a part of that unit


OrganizationPutrid68

That was a much better outcome than I expected. I suspect there were some dirty drawers on board.


anomalkingdom

Shit. He actually put it down. Bravo.


bucketsofpoo

didnt James Bond attend a weapons bazar at this location once?


fitzburger96

That was Courchevel, in the French Alps


Gripe

looks like if the pad had been empty the pilot could have put it down way easier on it


zebra1923

Pretty scary, I was relived to see the later shot with the copter on the bank. But what the fuck were those people doing so near the landing pad in the first place? Nuts.


themayora

".. so yeah we are down ...ok... im gonna need a crane... and... uh..... a fresh pair of underwear."


aikidoent

"technical snag in its rear motor" [https://www.news18.com/india/helicopter-carrying-pilgrims-develops-snag-makes-emergency-landing-in-kedarnath-8902315.html](https://www.news18.com/india/helicopter-carrying-pilgrims-develops-snag-makes-emergency-landing-in-kedarnath-8902315.html)


2Tall4U

There is no rear motor. This is a poor translation of a poor article. This looks like a classic case of LTE ( loss of tail rotor effectiveness).


erhue

insane stuff. Every year I learn of a new different deadly way in which a helicopter can crash. Vortex ring state blew my mind too


widgeamedoo

Pilot did well to keep the rotors from hitting the ground


CrashSlow

Hey Zeus was driving.


useittilitbreaks

I can see the problem, the rotors are hardly moving! /s


andypoo222

Some helicopter pilots absolutely amaze me with their ability to react quickly and precisely in emergencies


Stormj12

which did not occur here


andypoo222

An emergency didn’t occur?


Dre_Vent

Full left pedal, forward cyclic, lower collective (altitude permitting) and pray


Dre_Vent

Has to happen as soon as you notice the rapid right yaw.


goodolddaysare-today

It’s hilarious how a little less than half the people just stand there even when the guys in safety vests start running away.


BeautifulFantastic34

You can see one of the line guys “nope” out of there real quick haha


mdepfl

There’s a chart for that. Like in the AFM.


BenHippynet

Well if you will try and fly without switching on the spinny bit on the top these things will happen.


ycnz

Dear rich geniuses, when the ground crew are fleeing for their lives, maybe ponder joining them.


slogive1

Nope not getting in that after seeing what just happened.


nonono_username

Nobody comments on the fact that these stupid a**holes are all over the helipad waiting to embark, while they are numerous and this ain't a plane. As for the ramp workers they are just pathetic. Unprofessional, is the least one can say.


PulsarCollision

I thought for a moment it was going to be like a later episode of Airwolf where they were so cheap to even do a model, that all explosions happened behind a hill. Amazed the pilots got that down in one piece. I love the idea of helicopters. But they do seem like something that isn't meant to fly.


BoringBob84

They don't "fly." They are so ugly that the ground repels them.


bh205

Another Leonardo with LTE, weird...


AccidentallyBacon

****MORE RIGHT RUDDER!**** ~CFI's everywhere.


Ludwig_B0ltzmann

Ain't no way you'd catch me in a helicopter after Iran


AF_Blades

Do you hear a clanging sound where ever that pilot goes?


Blueberrydro

I think the main problem was his top blades weren't spinning until he started going down >.>


BrtFrkwr

Threw tail rotor shaft. Rolled it up in a ball.


rabbitisslow

LTE??


GotMilk707

What a savage! Amazing piloting.


Aayaan_747

It's expected, considering the pilot's balls of steel weighing down the chopper.


johnnyg883

Good pilot, great job keeping his cool.


bobre737

Clearly bro forgot to spin the big spinny thing on the top.


Shibari_Inu69

Pilot error or pilot excellence?


Red_Kys_Zone

tail rotor servo failure , pilot should be saluted for his quick thinking and landing the helicopter safely


[deleted]

When you ask your manager if you can take the new helicopter for a spin.


zippy251

That's a nice helicopter, would be a shame to see it completely destroyed


Ok_Elderberry_1369

Dang, he had NO T/R after that hard bounce/landing! That thing was not turning at all on shutdown! Lucky lucky lucky…should have been prepared for it in those conditions ugh. 😣


solocmv

All passengers wanting to go down the mountain your helicopter has just ‘landed’ and waiting for you to board. Anyone Anyone Hello?


Naysaydocwalker

Any Jake peralta fans here


Endeavouring_777

Buy that man/woman a beer.!


Allwingletnolift

Reaction time of a sloth


En4cr

The fact that there wasn't a prop strike was an absolute miracle. Pilot did a heck of a job too.


Icy_Huckleberry_8049

Perfect example of mountain winds and why they're so dangerous


Cessnateur

How do you know this can be attributed to winds and not to a loss of tail rotor authority?


Icy_Huckleberry_8049

it looks like he still has some control, but not total control.


pinkwhitney24

It doesn’t seem particularly windy. The clothes people are wearing don’t seem to be moving much at all. Not saying you’re wrong, just thinking that there might be another (or an additional) explanation.


fivechickens

Ran out of performance.


Icy_Huckleberry_8049

and couldn't correct for winds


fivechickens

Look at the bystanders legs. If there was any wind at all, he was into it. The slow approach and abrupt high OGE hover led to LTE when the tail was allowed to swing.


Nachtzug79

It seems it stalled because the rotor stopped going around.


Abject_Film_4414

Edit: I missed the joke entirely. Note: I still didn’t downvote though.


the_silent_redditor

I think it’s a joke about the frame rate synch. Which, for this sub, is quite funny!


Abject_Film_4414

/woosh on my part


happierinverted

Um, more *left* rudder? Surely not…


pattern_altitude

Helicopters aren’t the same as piston singles?!?!?! Surely not…