1.
General
This Advisory Circular
provides guidance and information concerning winch and autotow launching of
gliders and sailplanes. This
information does not supercede any previously issued Regulatory requirements
and provides Owner and Operators with additional guidance on how be in
compliance with those Regulations.
2.
Background
Ground launching of
gliders requires the coordination of both ground and flight crews to ensure the
safety of the launch. Launching of
gliders by either the winch or autotow method also requires that properly built
and maintained equipment be used.
3.
Winch and autotow
launching
Vehicle requirements
Any vehicle used for launching gliders, whether
winch or towcar, must have adequate protection for the driver and co-driver
against the ingress of launching wire, especially that occurring under tension
such as a cable-break. Such protection must consist of a combination of sheet
metal, wire cage material and armored transparencies (e.g. polycarbonate or toughened
glass) appropriate to the design and dimensions of the winch or launching
vehicle.
Winch-drivers must ensure that members of the
public are not permitted to remain in close proximity to the winch when
launching is in progress.
The winch or autotow vehicle, together with its
associated wires or ropes, must receive a Daily Inspection before flying
commences. This inspection must consist of, as a minimum, checking that there
is sufficient fuel, oil and water in the vehicle and that the engine is warmed
up and running properly. The vehicle must be fitted with a serviceable fuel
contents gauge or simple dipstick.
There must be provision for cable cutting or
releasing. The equipment for this purpose must be serviceable, effective and
capable of being operated without leaving the safety of the cab.
Launching wires/ropes
The glider end of winch and autotow wires or ropes
must be fitted with linked rings of a design approved by the glider
manufacturer or ECAA. The rings must be inspected before flying commences and
must not be used if damaged or distorted.
If solid wire is to be used, the recommended
standard for such wire must be "Range 2 Spring Steel". The two common
diameters of this material in use for glider-launching purposes are 2.8mm and
3.15mm.
The launching wire or rope must be inspected at
least daily and determined to be in a safe condition.
If a drogue parachute is fitted to the launching
wire, the minimum distance between the drogue and the rings shall be 5 meters.
The drogue parachute must be of such a design that it has no tendency to fully
or partially open during the launch.
If a two-drum winch is used, only one glider may
be attached to a cable at any one time. The idle cable must be separated from
the live cable by at least one wingspan and it must be securely anchored.
In a multiple-cable operation, the cables must be
laid out, and the first glider to be launched must be so positioned that the
first cable pulls apart from the second cable under tension. This ensures that
there is no risk of cables becoming crossed during the launching process.
Weak links
A weak link is mandatory and the specified
breaking strength placarded in the glider cockpit and on the glider's external
surface adjacent to each release hook.
The weak link must be placed on the glider side of the drogue, so that
the drogue is pulled well clear of the glider in the event of a weak link
break.
The "Tost" weak link system is
recommended. Knots in wire may only be used instead of a weak link if the
knotted wire has been tested and the results are available for inspection. Each
new batch of wire must be separately tested.
4.
Ground signals for
winch and autotow
These signals are defined as follows:
"Take
up slack" (self-explanatory).
"All
out" This signal means
all the slack is out of the wire and the launch may proceed.
"Stop"
(self-explanatory).
Hand signals from the pilot to the wingtip holder
are not recommended, on the basis that they distract the pilot from keeping
control of the glider when things can be happening very quickly and they also
detract from the ability to release the cable quickly should the need arise.
The following is the standard procedure to be
used:
I.
After attaching the cable and ensuring all clear
above and behind, pilot signifies ready for take-off by giving a thumb-up
signal with the left hand. This is confirmed verbally by the expression
"pilot ready for take-off".
II.
Crewmember (who must be adequately trained or
under supervision) raises wingtip and gives take-up-slack signal if satisfied
that it is still clear. This signal should be given verbally as well as
visually, to ensure that all persons around the launch point are in no doubt
that a launch is taking place. Pilot keeps left hand as close to release as
possible.
III.
When cable has tightened sufficiently, wingtip
holder gives all-out (full power) signal, again verbal as well as visual. The
pilot will have no input to this signal.
6.
Launching
responsibilities and information
·
The launch operator must be
aware of the maximum permissible launch speed for the glider and should be
briefed on the most suitable launch speed for the type of glider and any other
requirements the glider pilot may have.
·
Pilots should ensure only
non-compressive foam cushions (e.g. Energy Absorbing Foam) are used behind them
to avoid moving aft under initial launch acceleration.
·
The pilot must be ready for
launch prior to accepting the cable/rope for hook on.
·
The wing runner is
responsible for attaching the cable or towrope to the correct tow hook for the
type of launch being conducted.
·
The pilot is responsible for
releasing the cable at any time they consider the safety of the launch is being
compromised - e.g. a cable over-run, a wing drop or a veer on the take-off
roll.
·
The stop signal may be given by anyone who believes
that the launch should not take place for any reason. It may be given by the
pilot, the wingtip holder or by a bystander who sees something that nobody else
has noticed. No person should hesitate to give a stop signal if in any doubt
about the safety of the operation. When a stop signal is given, the pilot
releases the cable immediately.
·
To help the launch operator
to clearly see when the cable is released, the glider end of the cable must be
made visible by a parachute. The parachute must not be so large that it could
engulf the nose of the glider in the event of a cable break.
·
A winch and a tow-car must be
provided with a suitable cage or screen to protect the operator.
·
A “safety zone” is to be
established around a winch to ensure people not involved with the operation
remain well clear.
·
The winch engine must not be
run while work is being carried out on a cable.
·
Where a multi-drum winch, or
more than one winch are in operation and cable runs are closer than 60m apart,
only one glider may be attached to a cable at any time. After each launch the
used cable must be drawn into the winch before another cable is used.
·
All cables are to be treated
as “live” during a winch or autotow launch and must not be crossed, touched or
stepped on.
7.
Communication between
launch point and winch/towcar
An adequate method of communication must be
established between the launch point and the winch or tow-car, to relay the
above signals. The alternative methods of signaling are listed here.
Radio.
If used for launch signals, the radio must be
external to the glider. In this way, problems external to the glider and unseen
by the pilot can be detected and the launch stopped (e.g. airbrakes unlocked).
For this reason, the use of the glider's internal radio for launch signals is
prohibited. Terminology to be used is as described above.
For autotowing, a normal loudspeaker in the
vehicle is usually adequate to enable the tow-car driver to hear the signals
clearly. For winch-launching, the noise level may be too high for this to be
relied upon and a headset is recommended. It is especially important to be able
to hear a stop signal, which may be given after full power has been applied.
Telephone.
Terminology is the same as for radio and the same
principles apply to the use of headsets in a high-noise environment.
Single bat (paddle).
"Take up
slack" - Bat moved from side to side in an underarm motion across the
body.
"All
out" ("Full power") - Bat moved from side to side over the head.
"Stop"
- Bat held stationary above the head.
Two bats (paddle).
"Take up
slack" - One bat moved up and down alongside the body.
"All
out" - Two bats moved up and down each side of the body.
"Stop"
- Two bats held up over the head.
The single bat method is generally easier than the
two bat method. However, in summer conditions where mirage effects may distort
signals, the two bat system may have advantages in making signals less
confusing over winch-launch distances. Bats should be large and of a color
contrasting with the local environment.
Lights.
"Take up
slack" - Morse dashes.
"All
out" - Morse dots.
"Stop"
- Steady light.
A single "Aldis" type light is ideal for
signaling over long distances. In mirage conditions, a second light may be
added, in which case the "All out" signal becomes morse dashes on two
lights instead of one. As with two bats, this eliminates confusion. Car
headlights work very well for signaling, but obviously this removes the option
of doubling up in difficult signaling conditions.
Wing-waggling.
"Take up
slack" - Glider rocked laterally by moving wingtip up and down.
"All
out" - Wings held level.
"Stop"
- Wing down.
Wing-waggling must not be used unless a back-up
stop signal is available (e.g. bat), to cover the case of a stop signal being
required after the wing has left the wingtip holder's hand. An example of where
this might occur is the case of a glider's tailskid picking up the second wire
of a pair on a crosswind take-off.
Winch/autotow signals
during launch:
Too fast -
while still below upper speed limit, glider yawed until response obtained from
winch/car driver. If no response and speed continues to rise toward limit,
glider releases.
Too slow -
while still above 1.3Vs, glider nose lowered and the glider rolled from side to
side. If no response and speed continues to fall toward 1.3Vs, glider releases.
8.
Winch/autotow airfield
specifications.
The minimum field length for winch launching is
1,200 meters. The airfield should be clear of obstructions in the take-off and
landing directions.
The minimum field length for autotow operations is
1,600 meters. The strip should be smooth enough to drive a car or truck at
100km/hr. Obstruction requirements as for winch launching.
Consideration will be given to reducing the above
strip length for autotowing if the operational situation warrants it. An
example of a case for reduction of strip length is autotowing with
polypropylene rope, which does not need a drogue to stabilize it after release.
This eliminates the need for a long "run-off" to keep tension in the
rope after release and potentially reduces the strip requirement by up to 250
meters. The ECAA has discretionary power to vary strip length in any individual
case.
Winch launching is more awkward. There will
normally be no concession against the 1,200 meter requirement, because of the
risk that a short strip can promote early rotations into excessively steep
climbs. Any concession that may be granted will be a very minimal one.
9.
Winch/autotow drivers
Winch and tow-car drivers must be properly trained
with appropriate experience and must remain under supervision until all
emergency situations have been experienced or adequately simulated. Appendix
"A" contains recommended training syllabi. Winch or tow-car drivers who are under training are not
permitted to launch gliders on revenue flights. The Owner/Operator must train and approve launch operators engaged in
winch or auto-tow launching.
An approved winch/auto launch operator shall not undertake unsupervised
launches unless they have completed at least 3 launches by the same method in
the preceding 6 months.
10.
Winch/auto launch
emergency training (pilots)
During pre- and post-solo training, all likely
launch failure cases, e.g. wire/rope breaks and engine failures must be
adequately simulated during the launch. These exercises must be carried out at
a variety of heights, to ensure flexibility of response on the part of pilots
under training. It is not sufficient to carry out this training solely by
simulating the failure cases in free flight at altitude.
11. "Kiting" during
winch-launching
The practice of kiting during winch-launching
potentially endangers members of the public who have nothing to do with the
gliding operation. As kiting is only possible during strong wind conditions, a
cable-break (or running to the end of the cable on the winch) means the
certainty of the cable drifting downwind well outside the confines of the
gliding site, crossing public roads or becoming entangled with power-lines
outside the airfield. Innocent parties may thereby become electrocuted or
otherwise killed or maimed. For this reason, the practice of "kiting"
is prohibited.
12.
Airworthiness
·
A glider shall not be flown unless it has a
current Flight Permit Certificate of Airworthiness and a current Maintenance
Release.
·
An authorized inspector shall inspect all gliders
and the inspection certified prior to the first flight of each day and
following rigging or the completion of maintenance.
·
A glider pilot shall, if he/she is aware of
circumstances that cast doubt on the airworthiness of a glider, report the fact
to an authorized inspector and request that the glider be inspected.
·
The launch vehicle (which
includes tow planes, winches and tow cars) must be fitted with a tow release
mechanism. Such a release mechanism must allow the launch operator to release
or cut the towline or cable without delay or hazard when required.
·
The launch vehicle must have
a daily inspection by a person approved by the ECAA. The Owner/Operator shall
establish a suitable inspection schedule to ensure all launch equipment is
checked for its serviceability prior to use. Appendix "B" contains an example of a Daily
Inspection, but does not supercede information provided by the manufacture or
the Approved Maintenance Program of the glider.
·
The release mechanism on both
the glider and launch vehicle shall be tested prior to the first flight of each
day. Where a guillotine is used as the primary release mechanism, it is not
necessary to check the operation of the guillotine each day. However, the
launch operator must be satisfied that the general integrity and functionality
of the mechanism is acceptable. The tow release system inspection shall include:
Ø
Check security of attachment
of tow releases.
Ø
Clean and lubricate as
necessary.
Ø
Check that wear or corrosion
of the release mechanism is within acceptable limits.
Ø
Visually check to ensure that
neither leg of the return spring is broken.
Ø
Check for condition and
security of release actuating system. (Cables, pulleys, fairleads and
bellcranks).
Ø
Check at the release knob for
broken cable strands, and
Ø
Test operation of release
under load. Release forces must not be excessive.
·
The glider end of all launch
cables and towropes must be fitted with double rings meeting the manufacturer
specifications or approved by the ECAA. Rings at the glider end of the cable or
towrope must be inspected prior to each flight.
·
A weak link must be
incorporated in the towrope or cable. In no circumstances should it exceed the
weak link strength recommended in the glider's Flight Manual. Where no specific
strength is given, maximum strength of the weak link should be approximately
one and one-third times the gross weight of the glider being launched. For
cables, the weak link must be incorporated at the glider end of the cable
between the glider and the parachute.
Appendix A
Recommended Training Syllabus
WINCH OPERATOR
TRAINING SYLLABUS
WINCH DRIVING
Location and use of
Safety Gear
Use of Guillotine
Check of Winch Logbook
Daily Inspection of
Winch
Locating and
Stabilizing Winch
Start, Warm-up and
Shut-down
Wire Check and Joining
Rigging Safety Links
Parachute
Tow-out of Cable
Use of Brake
Radio and Signal
Procedures
Taking up Slack
All Out and Initial
Climb
Speed Control
Top of Launch
Release and Wire
Recovery
Launch With Crosswinds
Simulating Launch
Failures
Changing Winch Driver:
Briefing
RETRIEVE VEHICLE
OPERATIONS
Daily Inspection of
Vehicle
Airfield Driving Rules
Retrieving Cable
Fixing Wire Breaks
NON-NORMAL SITUATIONS
Wire Break at Low
Level
Wire Break in Full
Climb
Wire Break at Top of
Launch
Loss of Winch Power
during Launch
Launch Hang-up
TOWCAR DRIVER TRAINING
SYLLABUS
TOWCAR DRIVING
Location and use of
Safety Gear
Use of Guillotine /
Release System
Check of the Towcar
Logbook
Daily Inspection of
Towcar
Towcar Operating Area
Start, Warm-up and
Shut-down
Wire Check and Fixing
Breaks
Rigging Safety Links
Parachute
Tow-out of Cable
Use of Brake
Radio and Signal
Procedures
Taking up Slack
All Out and Initial
Climb
Speed Control
Top of Launch
Release And Wire
Recovery / Retrieve
Launch With Crosswinds
Simulating Launch
Failures
Changing Car Driver:
Briefing
NON-NORMAL SITUATIONS
Wire Break at Low
Level
Wire Break in Full
Climb
Wire Break at Top of
Launch
Power Failure
Launch Hang-up
APPENDIX B
DAILY INSPECTION SCHEDULE.
Clean
the glider. Use a soft rag or chamois and a little water. Wipe dry.
Note:
Not complete for a Powered Glider.
The
actual Daily Inspection will include, as a minimum, the following:--
(1) Start
at the cockpit.
Check
the Technical Log for:
Correct
glider,
Validity
of dates,
Reported
faults.
Identify
that the correct documents are in the correct glider.
(2) Cockpit.
Checking
for:
Condition
of interior of the cockpit. No dirt etc.
Seats,
cushions and straps, in good order.
No
loose objects in cockpit or on luggage shelf.
Battery(s)
in and secure, Instruments set and correct reading.
Radio,
Transponder, on and working, then turn off.
Instruments,
no broken glass, all pointers at zero, turn altimeter baro-scale
adjust knob to
zero all three pointers, then set QNH.
Removable
Ballast requirements and securing.
All
controls are full and free.
Lock
brakes open.
Canopy
for cleanness and correct locking. (Then close and lock it.)
Nose
wheel/main wheel for correct inflation and any damage.
Tow
Release, cleanliness and operation.
(3) Center
Section.
Checking
for:
Main
and drag wing pins home, secure and locked.
All
control connectors correctly attached and locked.
Ailerons,
Airbrakes, Flaps etc. Check safety
locking!
(4) Move
to the wing root, checking wing joint tape.
Walk
along the wing with one hand on the leading edge checking for
damage.
Look
along the top of the wing as you go, check the dive brake caps and
arms for play and
security, look inside air brake boxes for foreign objects, water, etc, then
under the wing checking for damage, check inside inspection covers.
(5) At
the tip, check for ground contact damage, and tip skid.
Look
along the bottom of the wing looking for discontinuity’s.
At
the aileron tip check for ground damage, and damage to outer hinge.
(6) Walk
along trailing edge of wing checking;
Aileron
hinges, control horns, flap hinges for play and security.
Check
attachment of control seals, and mylar tapes.
Top
wing surface for unevenness, damage.
(7) Moving
along rear fuselage, check for;
Damage
to rear fuselage, and static ports not blocked. (Or taped over.)
At
fin, Pitot and Static tubes secure.
Attachment
of tailplane
Tailplane
play.
(8) Walk
around tail, checking;
Tailplane
security and locking.
Elevator
and trim tab hinges and control connections. (Safety locking?)
Rudder
hinges and cables or pushrod connections.
Tailplane
to fin joint tape or fairings.
(9) Back
along second side of fuselage, as per 7. above, in reverse.
(10) Out along wing,
as in 6. 5, and 4. above, in reverse.
(11)
Back to leading edge wing root, checking along
nose, (static holes clear).
(12)
Nose Tow Release, cleanliness and operation.
And
back to cockpit.
(12) Carry out full
control movement check, this time using a second person to apply resistance at
the control surfaces, to ensure correct attachment.
(13) Minor faults (such as
gelcoat chips, etc.) which do not ground the glider, should be written up in
the Technical Log.
(14) Enter information
and sign Technical Log as “Serviceable” (S).
or
if defects are
found, as “Unserviceable” (U/S).