Winching Operations BGA Safe Winch Launching Initiative

Winching Operations BGA Safe Winch Launching Initiative
Presentation written by Andy Holmes BGA Winching Advisor Nov 2011 and revised Jan 2012

Review The Safe Winching Campaign has contributed to an improved accident record since 2006 Fatal/serious injury winch accidents 6 years 4 (none in 2010 or 2011) 6 years 18 Average 6 year period Review of main themes before 2012 Primary impact on accident record is pilot training/awareness, but also a contribution from winching operations side

Review Key Winching Operations campaigns so far: Safe cable speed
Excessive acceleration

Safe Cable Speed “Maintain shallow climb until adequate speed (1.5Vs) with continuing acceleration” If winch CAN’T achieve acceleration through 1.5Vs we have a problem! Need a Winch cable speed spec to back-up trained pilot technique For details see winchcablespeed.pdf on this DVD No point teaching pilots to fly a certain way if their winch is unable to provide enough speed. If trained flying technique is the safest way, we need winches to match their performance to the suggested flying technique

Recommended Cable Speed
Glider Type 1.5xVs (1g) Min. Winch Cable Speed (eg nil headwind) Rec. Winch Cable Speed (eg for hot day/tailwind) Ka6/Ka8 45kt 50kt 55kt Ka13/light single 60kt K21/standard class single 65kt Turbo/50l water 70kt The above shows that all winches should be capable of at least 60kt cable speed in order to launch ALMOST ALL glider types safely in NORMAL conditions In several low speed winches have been identified and solutions found Min. winch cable speed column adequate on a calm, cool day at sea level. Rec. winch cable speed column for hot day 20-25C, airfield above sea level and variable wind/occasional tailwind or wet wings. Colours show recommended min 60kt for most gliders in most conditions. 55kt winch OK so long as gliders launched restricted to K13s and other light wingloading gliders when zero headwind. Need 65+kt capability to launch the modern gliders with water ballast etc 65kt+ cable speed is beneficial if launching high wing-loading gliders (eg turbo/water ballast) or in worst-case conditions (hot day, light tailwind) <60kt winches require pilots to take extra care due to reduced energy margins during rotation in nil headwind conditions

Low Speed Winches Before campaign, over 10 winches in use unable to achieve safe cable speed Sometimes as low as 50kt max speed Regular abandoned launches Low energy = Difficult recovery Contributory factor in accident record? Some clubs visited had K13s abandoning launches on a summer’s day if the wind swung slightly, despite full winch throttle applied and max rpm achieved. Unable to launch glass gliders without decent headwind. Marginal speed from winch causes first part of launch to be high risk – minimum energy for any launch failure recovery

Solutions Used Increase Tost winch rev limit
Fit larger diameter drums to Tost winch Change gearing of homebuild diesel Buy used winch from another club Winch rebuilt including cable speed upgrade Solutions have ranged from cheap adjustments to full rebuilds/replacement

Symptoms of <60kt Winch
Speed “hovers” at <1.5Vs until you climb Abandoned launches in zero headwind K13s etc OK but glass pilots not happy Winch drivers using max throttle/revs but feel they still need more If you have these symptoms, the BGA Winching Advisor can assist with winch assessment Some clubs still have low speed winches as their backup or even their primary winch. More info in winchcablespeed.pdf – not a presentation but can be reviewed to understand further if you think your winch is a problem

Examples of <60kt Winches
6cyl diesel Supacat 55kt Tost IV with 4500rpm rev limiter 56kt Wild in 2nd gear with max 5000rpm 50kt Home-made winch ?? Old diesel winch ??

<60kt Winch Mitigation
If occasional tailwind, WAIT! Limit types launched if nil headwind Careful rotation and speed monitoring Winch driver use max revs if needed Take great care with visiting pilots not used to low speed winches Eg A 55kt winch is fine for K13s and light singles in nil headwind but needs a consistent 5kt+ headwind to launch heavier glass gliders with higher stall speeds safely. If you have a low speed winch, watch out for a visiting pilot from a high speed winch club, who may need some training to fly safely

Review Key Winching Operations campaigns so far: Safe cable speed
Excessive acceleration

Excessive Acceleration
Excessive winch acceleration can cause gliders to pitch up rapidly regardless of stick position Synthetic 8-10mm rope, which stretches during acceleration, can accentuate this Good winch driver technique can minimise this problem Synthetic rope has many advantages but the stretchy characteristic can cause problems, particularly if winch driver accelerates too quickly, and particularly when the rope is new. Would it benefit from being pre-stretched on airfield before use when new?

Excessive Acceleration
Diagram shows effect of harsh acceleration from winch – elevator is briefly “overpowered” by cable pull rotational couple and stops pilot controlling rotation rate. Pilot is not in control. Glider may stall or flick. Even if glider remains unstalled, cable break during this phase likely to result in an accident – see following slides Diagram courtesy of Steve Longland

Problems With Rapid Pitch-Up - 1
Reduced margin to stall speed! With harsh acceleration-induced rapid pitch-up, there is no chance to “maintain a shallow climb until adequate speed (1.5Vs) with continuing acceleration”. The glider is likely to pitch up rapidly before this speed is achieved, even with the stick forward. This, combined with the increase in stall speed caused by the rapid rotation rate, puts the glider very close to the stall, at no fault of the pilot

Problems With Rapid Pitch-Up - 2
Glider height and speed are low = low energy Glider is nose-high = rapid speed decay EVEN WITH A PERFECTLY FLOWN RECOVERY, A SAFE OUTCOME FROM A LOW LAUNCH FAILURE MAY NOT BE POSSIBLE IN THIS SITUATION. EVEN THE MOST COMPETENT PILOT CAN BE PUT IN THIS SITUATION BY BAD WINCH DRIVING Think about it! Harsh acceleration-induced rapid pitch-up can put the glider in a situation where a low launch failure may be unrecoverable. The best possible outcome may still be a heavy landing or worse

Solutions – Winch Drivers
Ensure type to be launched is known Smooth and progressive throttle opening 3sec acceleration with Skylaunch or similar Extra care with lightweight or stretchy ropes Engine sound assists acceleration judgement Ask for feedback from pilots Read “Don’t force your mate’s crate to rotate” in S&G April/May 2010 S&G article “Don’t force your mate’s crate to rotate” April/May 2010 has more detail. Suggest given as handout to winch drivers or even ALL pilots. Included on disk

NEW CAMPAIGN Fouling the Cable

Fouling the Cable Winch accident and incident reports reviewed for any trends 2011 had 6 events of cables fouling gliders; same as 2008/9/10 together Clearly this needs understanding and addressing, as worst-case cable fouling accidents can be fatal Downward trend of “hit cable” accidents has been reversed in 2011 quite significantly cable over wing accident was fatal

What Can Happen? Low launch failure - Parachute inflates - Cable hits or becomes tangled with glider Weak link break – Strop recoils into glider Take Up Slack jerk – Strop around wheel Landing near a moving cable/parachute Crossed cables Winch driver launches glider or moves cable when gliders/people on cable run

Safer Launch Failure Training

Instructors – Simulated Cable Breaks
Low launch failure training by pulling the release carries a high risk of fouling the cable ULTRA-LOW launch failures (<50’) are DEMO ONLY and are simulated by winch driver “power chop” BUT what about other height launch failures? What are the pros and cons?

Instructors – Power Chops
A “power chop” is an option at all heights Less chance of glider/cable conflict. The parachute falls away dead, behind the glider BUT instructor not fully in control of timing: Tricky to achieve requested height/position Committed to receiving the failure. What if pupil over-rotates or another hazard develops?

Instructors – Bung Pulling!
Fully in control of height/position for failure If not safe to pull it, not committed – can delay BUT Parachute WILL initially inflate, until winch driver reacts – Possible hazard for landing ahead If “pulling the bung” for a low launch failure, brief winch driver to stop immediately and be ready to avoid the parachute!

Comparison Diagram Typical sequences for both methods of launch failure training are shown in the next diagram In both cases, the failure occurs in position 2

typical locations of glider and parachute after recovery has commenced
Diagram courtesy of Steve Longland

Clearly, the chance of the glider contacting the cable or parachute is reduced if the “power chop” method is used for training low failures

Instructors – Decisions!
Always consider both methods for launch failures Medium & High failures not normally a problem Low/Land-ahead failures require consideration Height? Cable angle? Wind? Landing options? Parachute reaction? Winch braking distance? Pupil experience? Instructor experience? Choose the best option for each exercise Be confident with both methods If instructors are under-confident with either method of launch failure training, possibly useful exercise for refresher training/renewals

Recommendation Purely from the point of view of minimising cable fouling accidents, power chops are recommended for launch failure training <200’ If other factors outweigh this recommendation and you wish to pull the bung at <200’, then brief the winch driver and avoid the parachute Always weigh up the risks and benefits associated with each launch failure method at different heights and positions An alternative rule of thumb instead of <200’ is “before the full climb is established”

Still not convinced that power chops improve parachute separation?
Watch this video....

Click on picture to replay.
Click outside picture to advance to next slide

Bloggs would have to try very hard to hit it!
The parachute drops safely below and behind the glider, and doesn’t inflate until well clear. Bloggs would have to try very hard to hit it!

Real Launch Failures Unfortunately, we can’t arrange for real launch failures <200’ to all be power chops! The power may fail gradually or be inadequate from the start, or any part of the cable system may fail At low level, these scenarios can result in the parachute inflating near the glider Real launch failures at low level can be caused by errors from the ground team. Be “switched on” in the winch and at the launch point

Common Factors in Cable Fouling Accidents

Common Factors – Fouling Cable
No STOP signal, delayed or not spotted Parachute/strop arrangement poor Slow initial launch – abandoned Cable towout not straight Parachute not untwisted before launch Incorrect winch driver reaction to problem These were all factors in “hit cable” accidents and incidents from review

No STOP signal, delayed or not spotted Parachute/strop arrangement poor Slow initial launch – abandoned Cable towout not straight Parachute not untwisted before launch Incorrect winch driver reaction to problem

Possible Reasons for STOP After All-Out
Wing Drop Cable fouls glider Cable, weak link, parachute, shackle failure Abandoned launch Uncommanded cable release inc. hook failure! Crossed cables – another cable moves Low simulated cable break Conflict with landing or overflying aircraft Opportunity to get some discussion going – Are there any others? How much warning would you have for each? How important is it to respond quickly by signalling STOP with each? Who can call STOP? etc

STOP! - Winch Drivers Keep watching light signals while accelerating, until you get a good view of the airborne glider Always be ready for a Take Up Slack or All Out to change to STOP and ensure radio is audible SKYLAUNCH actions: CLOSE throttle instantly, PULL Drive lever back to Neutral, BRAKE HARD until drum stopped Watch glider and assess situation – Consider Guillotine, Drum Neutral, Engine off etc What are the STOP actions for your winch? May need modifying if your club has a different signalling system or a different winch type, but principle is the same

STOP! - Launch Signaller
Be ready to change signal to STOP! at any time Continue to monitor launch after All Out With lights, understand that winch driver will be focussing on glider soon after All Out Always back up a STOP light with a loud radio call to ensure prompt response from winch Preferable to have radios with good aerials, decent battery life and a clear channel Again, may need modifying if your club system is different. Generally need 2 systems to guarantee winch driver receives a stop signal, and signaller should always be ready to use both. Naff, cheap handheld radios which lose charge or have poor reception are common – get a decent reliable system! Signaller will have to shout on radio to be heard above winch engine

Recommended Cable Setup
Tost rings or equivalent “Strop” 3m (+/- 0.5m) Weak link in holder, with slot towards glider “Trace” 17m (minimum 12m, no maximum) Parachute – minimum usable size for site Max chute open diameter 1.5m steel/1.2m synthetic Swivel if needed, then winch cable Reduce metalwork where possible System has parachute at least 15m from glider Most clubs use this system already. Many have changed to it after an incident with a different system. 17m trace giving 20m total to parachute is recommended

Diagram courtesy of Steve Longland

Recommended Cable Material
For 3m “Strop” from Tost rings to weak link…. Rope (eg polypropylene – min stretch) 14+mm diameter, ideally encased in hose or pipe 4.5-6mm steel cable encased in hose or pipe 5mm+ Dyneema encased in hose or pipe Hose/pipe in good condition – no bare cable! Minimum diameter 12.5mm (½”) garden hose Same materials for 17m “Trace” from weak link to parachute, but if using 14+mm rope, hose/pipe not needed Large diameter rope of the least stretchy spec you can find seems to be the best/most user friendly

Advantages of Recommended Setup
Weak link and any bare cable clear of nosewheel/skid – less chance of hangup Weak link break/recoil - Less stored energy in short 3m strop than if weak link at parachute Diameter/material of strop less likely to catch in mainwheel during overrun Distance between parachute and glider allows time to react and avoids distraction There have been incidents with other systems which seem to show that this is the best setup. This setup is very similar to German system

Example Setup

What Can Go Wrong – An Example
Cable setup with only 5m from glider to ‘chute 15kt headwind Cable break before takeoff, at around 30-40kts ‘Chute flew back over the canopies obscuring the pilots’ view, then wrapped around cockpit Main wheel jammed and instructor trapped If the glider had been airborne, would have been a tricky landing with view obscured Club now uses recommended setup!

Luckily this incident took place entirely on the ground
Luckily this incident took place entirely on the ground. Cable setup with only 5m separation from glider to parachute. 15kt headwind. Main cable break during acceleration. Parachute flew back over the cockpit, obscuring the pilots’ view, then wrapped around the rear cockpit, trapping the instructor in the glider and jamming up the main wheel. If this had happened with the glider airborne it could have been different. This club now uses the recommended cable setup.....

Slow Initial Launch Incidents
Typically launching light gliders in a headwind Parachute inflates in front of glider due to low tension OR pilot releasing due to low speed Both caused by winch driver providing insufficient speed for glider to rotate safely ½ of incidents = Skylaunch with throttle stops ½ of incidents = other types without stops

Skylaunch: Headwind > 10kts
Throttle stop setting may be ideal once glider in full climb, but may be insufficient to give normal acceleration through wind gradient Throttle stop is JUST A GUIDE to approx power Always be ready to adjust throttle as needed LISTEN TO ENGINE - smoothly increase throttle if engine sounds laboured/doesn’t accelerate WATCH GLIDER - smoothly increase throttle if glider doesn’t enter full climb normally

Skylaunch: >10kt Headwind Option 1
Underestimate Headwind by 1 notch/5kts Eg In 20kt headwind select 15kt setting Accelerate smoothly to throttle stop Watch glider and listen to engine for feedback – adjust power if required Be ready to smoothly reduce power once glider is through wind gradient Rest of launch normal Both methods used and work fine. If glider in full climb at correct speed before you reach throttle stop – stop accelerating. Always be ready to continue past the preselected stop if engine sounds sluggish and glider doesn’t rotate normally

Skylaunch: >10kt Headwind Option 2
Select correct headwind Accelerate smoothly to throttle stop then slightly beyond (5-10mm normally sufficient) Watch glider and listen to engine for feedback – adjust power if required Be ready to smoothly reduce power once glider is through wind gradient Rest of launch normal Both methods used and work fine. If glider in full climb at correct speed before you reach throttle stop – stop accelerating. Always be ready to continue past the preselected stop if engine sounds sluggish and glider doesn’t rotate normally

Skylaunch Throttle Stops
Useful guide and training aid - consistency Work well in light winds, but more judgement needed in stronger headwinds Drivers who can only “launch by numbers” are not fully trained winch drivers! Drivers should have sufficient judgement to be able to adjust power as required Trend for training new winch drivers in minimal launches using throttle stops needs watching out for. They also need enough experience to have some element of judgement before being signed off

Other Winch Types Same principle applies to most winch types
In a strong headwind, the lower power-setting required in the full climb may not be sufficient for the glider to rotate safely Need to accelerate the glider through the wind gradient first, then adjust power in full climb If glider doesn’t rotate normally or engine sounds laboured, smoothly increase throttle Ask your winchmaster for advice specific to your type of winch Other winch types with Skylaunch throttle stops fitted – same advice. Any other winch type – just be aware that although the power setting once established in the full climb may need to be less on windy days, you still need to get the glider accelerated through the wind gradient first. This means that the initial power setting for acceleration and rotation is likely to be higher than the power required in the full climb

Diagram of Headwind Launch
The following diagram illustrates option 2 for driving a Skylaunch in >10kt Headwind Option 2 is selecting the correct headwind, but initially accelerating slightly beyond the throttle stop for the first part of the launch The general principle applies to most winches Don’t forget that the windsock indicates the wind strength at 10-15ft above the ground. Glider headwind below this height is likely to be less than indicated by the windsock Glider wing is only 2-3ft above ground during ground run, but typical windsock heights 10-15ft. Therefore, headwind affecting glider wing likely to be less than indicated by windsock during first part of launch

Diagram courtesy of Steve Longland

Crossed Cables - Causes
Towout not straight Cables not separated at launch point Glider queue too close to cables Winch driver launches with previously used cable too close to the cable in use. Has to abandon launch when cables tangle Towout driver hooks cables up incorrectly Winch driver moves winch with multiple cables out on field!

Wonky Towout? Drive full length and ensure separation
If clear, launch cable inside of bow first If doubt, wind inside cable in - launch 2nd only DO NOT be pressured into launching Rebrief/retrain/replace towout driver! If using a single cable in a large bow (eg winter ops), ensure no landed gliders, people or vehicles are within the bow before launching!

Parachute Not Untwisted
Any twisted part of the cable system can create a jerk during acceleration and rotation This can be enough to briefly open parachute, or alarm the pilot sufficiently for him to lower the nose or release at low level To avoid these incidents ALWAYS ensure cable system untwisted before hooking on

Winch Driver Reaction With low launch failures, glider/cable separation CAN’T be guaranteed – CABLE MUST BE STOPPED IMMEDIATELY SKYLAUNCH actions: CLOSE throttle instantly, PULL Drive lever back to Neutral, BRAKE HARD until drum stopped Watch glider and assess situation – Consider Guillotine, Drum Neutral, Engine off etc For higher failures (eg glider doesn’t land ahead) initial actions same, but once glider and cable well separated, winch driver can continue winding in if safe to do so. If in doubt, continue to a full stop, then assess. If cable drops out of sight, check clear to wind in by radio or by driving down and checking!

REVIEW

Cable Fouling Review Power chop for ultra-low launch failure demo
Power chops recommended for failures <200’ Think about best method each time Improve STOP communication and procedures Use recommended cable setup Use sufficient throttle for rotation in headwind Straight cable towouts and untwisted ‘chutes STOP drum immediately with low failures Train winch drivers fully – not “by numbers” Review of ways to stop “hit cable” accidents and incidents

Summary Gliders being fouled by winch cables is a threat
There is plenty we can do to reduce the risk If everyone is “switched on” we can all help Target is to revert to downward trend of “hit cable” incidents and accidents from 2013 on Keep reporting winch accidents/incidents to help our work to understand and reduce them Thank you Please contact BGA Winching Advisor if your club disagrees with any of the advice contained so it can be reviewed

Winching Operations BGA Safe Winch Launching Initiative

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