DG1000 glider winch launch failure due to wrong weak link
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- Опубліковано 1 чер 2018
- This video records what can/will/should happen when cable launching with a weak link rated for a lighter glider.
The wrong weak link was attached before the launch due to a mix up changing over from a single seat glider (blue) link to a two seater link (black). I should have verified the correct link was used before being hooked on. I'll add further comments below later on the lessons learned from this experience. As a relative novice pilot, I welcome constructive peer review comments.
So, how did the mix up occur? The comments below were recorded by one of the ground crew (an instructor) assisting preparations.
"You were about to go solo in the DG1000.
The other instructor was trying to remove the blue link from the previous launch of the DG100 [a single seater] but with gloves on and with difficulty. I offered to take over which he accepted.
I removed the the link from the tow rope and gave the link to the other helper. However he accidentally took the main tow rope, not the weak link, and when I realised I was trying to link a black link to a blue link I called him back over and we swapped the tow rope for, what I thought was, the blue link but it was the black link that I must have given him.
I proceeded to couple the weak link to the rope and then proceeded to connect the link to the glider piloted by Mark.
Mark did not request to see the link nor did I offer to show him the link. This is how the blue link got erroneously connected to the DG1000.
After discussions with Mark we both agreed that the checks CB SIFT BEC should have W added which is CB SIFT BECW where W is the check on the weak link. Had that been part of the check list, this would not have occurred."
Launch failures due to any cause are something we train for. Before every launch, we specifically consider possible eventualities such as cable breaks and winch failures and decide on what actions we will take. For low level breaks, landing straight ahead is usually the safest providing the airstrip is long enough. For higher level breaks, the options are more likely to require a turn back and abbreviated or normal landing. Wind strength and direction are also variables that come into the considerations.
For this launch with little or no wind, my options were: land straight ahead (runway 03) if low, do a 3/4 turn and land on the cross runway (29) if above 500-600 feet, or do a more or less normal circuit back to the same runway.
In this event, since it was still quite early in the climb, I elected to land straight ahead. The break occurred with about 450ft indicated (~320ft AGL) and descent commenced from about 600ft. In reality this was probably sufficient height to safely commence either of the other go round options. Once committed to plan A and seeing that a satisfactory aiming point could be identified I stuck with it. However, this did necessitate descent on full airbrakes all the way to the ground which is not entirely ideal.
Lessons learned:
- ALWAYS positively verify the correct weak link. Don't rush this step.This is even more critical in a lighter glider to avoid over stressing risks.
- The cross over decision point between landing ahead and going around may not be easy to judge (probably more so for a novice), particularly in a early climb break
- In spite of the actual or apparent length of the strip available, factors like the narrow section on this vector near the other end and the winch position may mean it's not as long as you think - Спорт
At our club, before hooking on, the pilot specifically requests and states the link necessary and the tip runner also deliberately shows and states what link he is going to attach to the plane before actually hooking on and continue with the launch sequence. Really helps since little mixups like this can happen very easily 🙈 But well done on safely getting back to the ground!
Fast reaction, well done. I would have done the same having that much space ahead. At my home airfield I would have done differently, as we do not have that much area ahead. But it depends on several different conditions which decision to make. Yours was the right one. 👍
This happened on my first solo flight (no undue tension - just a weak link). I thought at first the instructors had done it for a joke - until I saw the look on their faces. Fortunately had just been practicing for the event and landed ahead (a good long runway). They got me back onto the winch before I had time to really think about it.
@Ian Marsh Well done! I've had at least one weak link break like this where the speed/tension was within normal range. It is possible (and I've seen the evidence) for a weak link to be stressed in a previous launch and hence fail at a lower than rated tension.
@@MSBWilson German weak link producer TOST recommends to change them after 100 launches at least after 1 year in service.
Material fatigue and previous overloading stresses them. On TOST weak links there is a round hole in the middle, which determines the breaking force by different Ø.
When the hole is elongated, it is a sure sign of previous overloading.
Do you use single or double (one with normal round holes the other with long-holes at the connecting sides) weak link configuration at your club?
Another important thing (especially on sandy/rocky fields) is the protection sleeve for the weak link(s), and securing them not to grind over ground on tow back from the winch to the start.
But the best e.g. blue 600 daN has no chance against a DG1000 which needs a black 1000 daN one ;)
@@hectorpascale1013 Thanks for your comments Hector. I believe we use the single hole links. I'm not sure if we have a routine procedure for replacing them after 100 launches but I suspect we break them before they reach 100. We do quite a lot of single launches and breaks in windy conditions are not uncommon. We do take good precautions to protect them during launch cable tow out - the strop, drogue chute and link are loaded on the deck of the tow out truck.
And you are right about launching a DG1000 on a blue link - pretty predictable outcome! :-) All the more reason to be vigilant and verify the correct link before *every* launch, particularly in a single seater.
Great video. Thanks for the analysis. I'm just getting started with gliding and winch launches so this was very educational. Thanks again.
Thanks for the feedback. All the best for your gliding and soaring experience :-)
I had a winch launch failure on my second solo (just after my first one). I am very thankful to my instructors that they did a good job in preparing me. Similar to the video, I just landed straight ahead (to the right somewhat, to avoid hitting the winch).
I had it just before my first solo, when i was flying last time with instructor. It was quite surprising - line hit bottom of the glider very loud (fuse break) and i thought something breaked under me but then i realized what happened and glider was fully controlable and flying normal so then it was calm. We had ~150-200m if i remember so we choose to do 2 turns and land against wind as normal ;) All that time i was flying so it was a nice training before solo :P
Ps. Choosing what to do is very tricky at about 100m (land straight or 180 turn) but luckly we had way more and simple decission ;)
Good to see you coped with it
Don't panic push stick forward don't rush wait for airspeed to get to flying speed then make the call land ahead or turn
Well done
Thanks Neil. I've had a bit more practice/experience since then. I've had 5 or 6 more cable/weak link breaks since then, mostly with comfortable circuit height but one very low in extreme crosswind turbulence that was a bit more exciting :-)
Fly safe.
When I gained my winch launch certificate ,the instructor said to me that a negative g nose over is absolutely desirable.
When you consider the dangerously unnatural nose attitude during a winch launch,it made common sense.
Well done!
I'm sure you will be thoroughly checking just which weak link is on the line from now on. When there's a number of people fiddling with weak links rather than just the pilot, there's more opportunities for miscommunication.
Once you have full spoilers out you can steepen the descent by increasing the airspeed to around 70 kt. Drag increases with the square of the airspeed. Might not work in an older glider with dinky spoilers, but works fine in a Twin Grob.
I am surprised it held up for so long!
After I saw the word Papawai in the description I knew I had to say that's where I fly!
Nice flying!
Thanks! 👍
Well flown. Not had a real cable break myself but this is where all the training comes in. Looks like you had plenty of space ahead though as others mention a short circuit or 180 may have been an option (difficult to say unless you are in the cockpit) Once you've made the discussion you should stick to it so nicely done.
@cirrus4000 Thanks for the comments. In the last 2 years, I've had 3 weak link breaks (2 due to wrong weak link, one in severe turbulence), 1 actual cable break while still on the ground, and 2 premature releases (i.e. belly hook released unexpectedly) one of which was also in severe turbulence which may have caused a back release. That last one was the most challenging because I had unexpectedly launched into a very turbulent cross wind layer that had just hit the airfield (~30-40 knot gusts) and was offsetting hard into wind. One of my pre-flight eventuality options was to land on the cross vector which happened to line up with the direction I was banking into. Still, a pretty wild ride there for a bit!
Good video. Good landing. Surprised you didn't do a circuit though ? Looks like 600ft.
Yes, you are probably right. By the time I leveled off, I actually had about 500 feet AGL (The altimeter is set to height above sea level, not 0, for our site). My choice was a straight ahead landing as the safest option on our strip on this vector as there is plenty of room ahead. Better (for a relative novice pilot) I think to have a longer tow back to the launch point than do a hurried turn and get too low or stall in the process.
Fly safe :-)
@@MSBWilson humbly - even as a novice - I'd have considered coming a slip to really get some altitude knocked down. But boy those DG brakes got you down fast in any event! Man! Very powerful. Nicely done!
Absolutely right Mark. Land ahead if you can, every time. You will have had enough excitement already and it by far the safer option.
I was a bit perturbed at seeing how much height there was to lose in the space available. Turns out to have been the right decision to land ahead though.
Gestion sans faute de cette casse-câble basse hauteur. C'est bien l'ami !
This could've been prevented by doing what we do over here in the UK where the pilot is shown the weak link before the cable it attached to the glider
Quite so. It is part of the standard operating procedure. Reviewing and learning from incidents like this has helped reinforce the importance of this check for both ground crew and pilots, me included.
well resolved!
In our club the person attaching the cable shows the link to the pilot. If pilot is happy the launch goes on ....
Thanks Piotr. Yes, I agree, and this is also our club's correct procedure. This launch was an example of what can happen if these procedures are not followed by both the person hooking on and checked by the pilot. It's possibly also an example of oversights, errors or threats that can creep in if procedures are hurried or interrupted. I have experienced that situation too where the launch process was rushed by the instructor (who was tired after a long day) to avoid being delayed by another landing glider.
Fly safe :-)
The first push after the break was good ( the reaction ), but the forward/backwards movements were not good or indeed necessary I’m afraid and could be dangerous particularly if you had not had sufficient speed.Well done for a perfect decision to land ahead ( always safest ). Stress levels are always high after a launch failure but you did ok, just watch that stick wiggle!
Fair comment on the stick movements - first time nerves I suspect :-) Nevertheless, I was watching speed continuously to make sure safe flying speed was maintained. Subsequent cable breaks (I had about five breaks or pre-releases in about a year) went more smoothly.
Great reaction, looked text book to me
The fields behind Winches are normally very long. So in low hights, u can saftey land. in case of higher altitude, make a turn and land. U can train that. Its not so bad to do this.
well done
Had a rope break on this vector today, at about 300 feet... glad instructor hadn't handed controls over as that was the plan!
Was my 13th flight....lol
Thanks for sharing! It scared me a little though for not making a circle, but its a little hard to 'judge' from this footage. It looked safe enough >150 meter to perform an alternative pattern. Nice long and safe landing though. Take care....
Recommended practice is: When you have achieved the approach speed, land ahead if it is safe to do so. If not, turn in the direction you decided before take-off.
A risk for less experienced pilots is to do a 'panicked' turn and risk stalling at low altitude. I've seen this sort of situation develop, fortunately without incident. Fly safe :-)
Depends on weather you are going to end up with a tail wind if you turn a 180 from your take off vector I would think.
at our club we have defined thresholds for emergencies, land on the runway or extension (not above 30 m AGL as the runway is too short), straight ahead for up to 150 AGL. Above 150 AGL turn back 180° and land with tail wind (just two runways for us).
Having check your altitude you already have your desition made.
Good job landing the DG
not above 30m?! with 30m you don't even have enough altitude to properly recover speed, let alone a turn...
@HaraldDV Because a break can occur at any point in a launch, it is very important to make the transition from lift off into the full climb gradually and in such a way that a safe recovery can be achieved. A common rule of thumb is that you don't start the rotation into the climb until sufficient airspeed is achieved (e.g. 50kts and increasing) then make the transition smooth and over a count of about 5 seconds. In this way, you will still have a safety speed margin in the low altitude phase for pushing over into an ahead landing. Fly safe!
@@MSBWilson we land straight under 100m AGL. This gets higher with more wind.
I have never seen a real rope break between rolling on the ground and after rotation, the high load comes after rotation, and even during rotation you get higher than 30m
@@Haralddv I've had one cable break during the ground roll and an low level hook disconnect during my 1st launch in a new type - (see ua-cam.com/video/osVatu4_kkM/v-deo.html). In the disconnect case, we suspect that the tow ring wasn't quite correctly located in the belly hook. I'm pretty sure I didn't inadvertently pull on the release and we couldn't find any issue with the belly hook mechanism. However, just goes to show the unexpected may happen, unexpectedly! It hasn't happened again in many more launches in the Libelle.
Good safe choice....airspeed first......land ahead into wind prudent choice where you were.
Thanks! 👍
Fly safe!
Good proceedure. Instant reaction . Instant commital .
Wow. Massive field compared to ours !!
We usually get at around a 2000ft launch on this vector but recently we've tried moving the winch further down and put the launch point further back and can now get around 2500ft launches. The east/west vector is somewhat shorter, and has a drainage channel about half way along, it but still provides a good option for westerly conditions. Happy soaring!
Nicely :)
Wow you have a long arse airfield 😂
well shit .. that was a quick flight
Yup! :-)
I think my shortest was about 15 seconds when training for this sort of launch failure.
Quick way to find out how dirty your cockpit is
:-)
Also a quick way to realise you forgot to adequately secure your cell phone in the side pocket when it flies up and falls on your head as I was reminded recently under similar circumstances. Doh!
It's not a bad idea to include 'Security of loose object's as part of the 'S' in the pre-flight CB SIFT BEC checks.
See also Ian's cable break :-) ua-cam.com/video/hBlctKBy2tc/v-deo.html
The break occurred at 450'. Shouldn't that have been a reduced circuit?
Not necessarily. The normal recommendation is: When you have achieved the approach speed land ahead if it is safe to do so.
The indicated 450' is about 300' above the ground (the airfield is at ~140').
See page 10 of training.gliding.co.nz/pluginfile.php/373/mod_resource/content/4/Safe%20Winching%20Booklet%20BGA%206th%20Ed.pdf
We have quite a long field so landing ahead remains an option at this height. For a novice, this is a safer option than doing a potentially paniced turn ,leading to a stall, to do a reduced circuit .
Fly safe! 🙂
Es war viel zu hoch und gerade zu landen.
Hello! Is it possible to contact you regarding this video? (i.e. via email) I would love to discuss getting permission to use your video in a video production and for licensing in general if possible. Greetings!
I don't know why everyone says that this was a good landing?! You were way to fast on touchdown and while you were rolling you balanced the airplane on the main wheel and almost put the nose into the ground. Which could have resulted in a serious crash. You want to glide as long as you can and land the plane with minimal speed and then, once on the ground, pull the stick all the way to your stomach, to force that tail into the ground, which will make you decelerate faster and make rolling way more stable. Now, you might say you did not have enough room for that. To which I would say your height was more than enough for a short traffic pattern. On many sailplane fields you wouldn't have any other choice anyway.
Any landing you walk away from, is a good landing.
@@kdaniel8721 its any landing that the aircraft is reusable!
That was a great landing given the circumstances. It's easy to have a go at someone from your armchair. Yeah he could have pulled the stick back further on touch down but it was still a good landing.
"...to force that tail into the ground, which will make you decelerate faster and make rolling way more stable. Now, you might say you did not have enough room for that. To which I would say your height was more than enough for a short traffic pattern." That didn't make any sense. Why would he not have enough room if doing so would have made his ground run shorter? Stick to 10 view COD videos.
@@fudruckers3916 Yeah agreed, landing wasn't held off at all and too quick, but hey it doesn't have to be in these situations. 10 quid MowTee is a student pilot who thinks he's a big shot cos he's done his first cable breaks and he's giving it the big'un in the youtube comment section. Stick to 10 view COD videos mate :D
"pull the stick all the way..... make you decelerate faster" that is not really the case with a tailwheel
Altimeter not set to zero on start.
Correctly spotted :-)
Our standard procedure is to set the altimeter to the airfield altitude (~140 ft AMSL) prior to launch rather than to zero. In practice, you have to be prepared to land in a different location than you took off which could easily have a lower or higher altitude. Therefore, it is important to become proficient at judging circuit and final approach heights without strict reliance on the altimeter. Even if you are landing in the same place, it is quite possible to have weather related air pressure changes (particularly during a longer flight) that could shift your reference setting enough to make it unreliable for approach height determination.
One of the training/evaluation exercises we do before being cleared for solo is a 'no instrument' flight (airspeed and altimeter blanked off) to re-enforce this. (See also: ua-cam.com/video/LOAy-TEushk/v-deo.html)
Happy flying.
@@MSBWilson That's interesting to know how the procedures differ between clubs. In my club it is part of the pre-start checklist to set the altimeter to zero, especially for pattern training, possibly not if you're planning a landing at a different airfield.
I believe airliners and the such start with the altimeter set to QFE and switch to QNH at some specific altitude, and are forbidden to loiter in the range when the two settings might overlap.
@@kardRatzinger Altimeter is set to ISA (29.92"Hg/1013.2mb or hPa) at FL180. So yes QNH at FL180, below QFE of nearest station. (in US). Haven't heard about the "no loitering" thing though, sounds like a theoretical exercise.
@@kardRatzinger Airliners set their altimeter before take-off to QNH (so the altimeter shows the elevation of the airfield when on the ground) and after the transition altitude to standard (1013 hPa). When descending through the transition level, the altimeter is set from standard to the local QNH again. Procedures in Russia are different.
The pre-flight item for an altimeter is not to specifically set it to zero, it’s to set it either for the field or above sea level. When you’re learning it’s typical to set it above the field as it’s less confusing and you’re most likely going to land back at the field. Later on it’s better to set it above sea level as calculations from 0 are easier plus air space is set above sea level.