Glider release failure?

[Duster[_3_]]

Has anyone heard of or experienced a case where the pull of the glider's release handle during flight failed to result in the rope dropping off the release mechanism? Last summer two of us were under tow when turbulence threw us too high above the tug (or sink drove the tug too low) @~2,000ft agl. One of us remarked that "We need to release", and we each pulled the handles.. I pulled mine again at least twice and I distinctly remember the cable moving a few cm each time. We turned away from the tug, but after a few seconds I thought I heard a loud bang accompanied by a slight, transient vibration, but no nose movement. Pulled the handle several more times. First I'm thinking we hit the towplane, but then I saw him below and ahead of us with about 4-6' of rope trailing off his Tost release, then radioed him to report the rope break. An inspection did not reveal any evidence that the rope had gotten hung up on the gear doors, wing or empennage. Testing the release gave the normal rope drop after a few mm's of pull, even under heavy tension. The other pilot didn't hear the "break", but the flight logger did record it as a spike of noise on the trace. Any hypotheses on this one?

Perhaps in a related incident, the 2017 Pawnee fatality accident report where there was intra-cockpit video, the glider pilot reported that (after an admitted distraction) he got high on tow, noticed some rope slack, pulled the dive brakes and released the rope. The GoPro showed almost full deployment of the spoilers, first a short movement of the release cable, followed by a "snapping sound", followed by a longer slack in the cable. The report also revealed a short length of rope hanging from the Pawnee (with a high tension break). The NTSB could only conclude that the tug pilot had, for some unknown reason, lost control. Other factors were suggested. The similarity between that incident and ours was that each glider pilot pulled the release handle, assumed the rope fell away but ended up with a rope break. That's my reading of the report, but I may have missed something.

[[email protected]]

> glider pilot pulled the release handle, assumed the rope fell away

Why not look to make sure the tow has the whole rope?
It keeps him in site and only takes a second of so.

If there is any doubt that the glider is reliably releasing, then seems like inspecting both the release and logs to see if it is due for rebuild.

[[email protected]]

On Thursday, May 14, 2020 at 3:35:18 PM UTC-4, Duster wrote:
> Has anyone heard of or experienced a case where the pull of the glider's release handle during flight failed to result in the rope dropping off the release mechanism? Last summer two of us were under tow when turbulence threw us too high above the tug (or sink drove the tug too low) @~2,000ft agl. One of us remarked that "We need to release", and we each pulled the handles. I pulled mine again at least twice and I distinctly remember the cable moving a few cm each time. We turned away from the tug, but after a few seconds I thought I heard a loud bang accompanied by a slight, transient vibration, but no nose movement. Pulled the handle several more times. First I'm thinking we hit the towplane, but then I saw him below and ahead of us with about 4-6' of rope trailing off his Tost release, then radioed him to report the rope break. An inspection did not reveal any evidence that the rope had gotten hung up on the gear doors, wing or empennage. Testing the release gave the normal rope drop after a few mm's of pull, even under heavy tension. The other pilot didn't hear the "break", but the flight logger did record it as a spike of noise on the trace. Any hypotheses on this one?
>
> Perhaps in a related incident, the 2017 Pawnee fatality accident report where there was intra-cockpit video, the glider pilot reported that (after an admitted distraction) he got high on tow, noticed some rope slack, pulled the dive brakes and released the rope. The GoPro showed almost full deployment of the spoilers, first a short movement of the release cable, followed by a "snapping sound", followed by a longer slack in the cable. The report also revealed a short length of rope hanging from the Pawnee (with a high tension break). The NTSB could only conclude that the tug pilot had, for some unknown reason, lost control. Other factors were suggested. The similarity between that incident and ours was that each glider pilot pulled the release handle, assumed the rope fell away but ended up with a rope break. That's my reading of the report, but I may have missed something.

We have seen a couple cases where the ring got hung on the release arm due to slack.
Arms on ships that have low ground clearance have been known to get deformed or have a burr such that this can happen. We just reworked the skid on our 1-34 to get more ground clearance due to this.
It is rare but it can happen.
UH

[[email protected]]

On Thursday, May 14, 2020 at 8:03:08 PM UTC-4, wrote:
> On Thursday, May 14, 2020 at 3:35:18 PM UTC-4, Duster wrote:
> > Has anyone heard of or experienced a case where the pull of the glider's release handle during flight failed to result in the rope dropping off the release mechanism? Last summer two of us were under tow when turbulence threw us too high above the tug (or sink drove the tug too low) @~2,000ft agl. One of us remarked that "We need to release", and we each pulled the handles. I pulled mine again at least twice and I distinctly remember the cable moving a few cm each time. We turned away from the tug, but after a few seconds I thought I heard a loud bang accompanied by a slight, transient vibration, but no nose movement. Pulled the handle several more times. First I'm thinking we hit the towplane, but then I saw him below and ahead of us with about 4-6' of rope trailing off his Tost release, then radioed him to report the rope break. An inspection did not reveal any evidence that the rope had gotten hung up on the gear doors, wing or empennage. Testing the release gave the normal rope drop after a few mm's of pull, even under heavy tension. The other pilot didn't hear the "break", but the flight logger did record it as a spike of noise on the trace. Any hypotheses on this one?
> >
> > Perhaps in a related incident, the 2017 Pawnee fatality accident report where there was intra-cockpit video, the glider pilot reported that (after an admitted distraction) he got high on tow, noticed some rope slack, pulled the dive brakes and released the rope. The GoPro showed almost full deployment of the spoilers, first a short movement of the release cable, followed by a "snapping sound", followed by a longer slack in the cable. The report also revealed a short length of rope hanging from the Pawnee (with a high tension break). The NTSB could only conclude that the tug pilot had, for some unknown reason, lost control. Other factors were suggested. The similarity between that incident and ours was that each glider pilot pulled the release handle, assumed the rope fell away but ended up with a rope break. That's my reading of the report, but I may have missed something.
>
> We have seen a couple cases where the ring got hung on the release arm due to slack.
> Arms on ships that have low ground clearance have been known to get deformed or have a burr such that this can happen. We just reworked the skid on our 1-34 to get more ground clearance due to this.
> It is rare but it can happen.
> UH

I also should have mentioned that a tight tow hook may not open without rope tension, You could pull the release with slack, hook sticks, and release arm closes on hook again.
Good practice would be to hold the release until the rope is confirmed gone..
I'll shut up now.
UH

[son_of_flubber]

On Thursday, May 14, 2020 at 3:35:18 PM UTC-4, Duster wrote:
> Has anyone heard of or experienced a case where the pull of the glider's release handle during flight failed to result in the rope dropping off the release mechanism?

Does the glider have a Tost release?

[Marton KSz]

Witnessed this happening with an SZD-9 Bocian, not being able to release after having been winched to 1000ft. The pilot yanked the release while trying to descend, circling in place. He then asked the passenger in the front seat to pull the release, eventually they got rid of the rope at around 500ft.

[Frank Whiteley]

On Thursday, May 14, 2020 at 1:35:18 PM UTC-6, Duster wrote:
> Has anyone heard of or experienced a case where the pull of the glider's release handle during flight failed to result in the rope dropping off the release mechanism? Last summer two of us were under tow when turbulence threw us too high above the tug (or sink drove the tug too low) @~2,000ft agl. One of us remarked that "We need to release", and we each pulled the handles. I pulled mine again at least twice and I distinctly remember the cable moving a few cm each time. We turned away from the tug, but after a few seconds I thought I heard a loud bang accompanied by a slight, transient vibration, but no nose movement. Pulled the handle several more times. First I'm thinking we hit the towplane, but then I saw him below and ahead of us with about 4-6' of rope trailing off his Tost release, then radioed him to report the rope break. An inspection did not reveal any evidence that the rope had gotten hung up on the gear doors, wing or empennage. Testing the release gave the normal rope drop after a few mm's of pull, even under heavy tension. The other pilot didn't hear the "break", but the flight logger did record it as a spike of noise on the trace. Any hypotheses on this one?
>
> Perhaps in a related incident, the 2017 Pawnee fatality accident report where there was intra-cockpit video, the glider pilot reported that (after an admitted distraction) he got high on tow, noticed some rope slack, pulled the dive brakes and released the rope. The GoPro showed almost full deployment of the spoilers, first a short movement of the release cable, followed by a "snapping sound", followed by a longer slack in the cable. The report also revealed a short length of rope hanging from the Pawnee (with a high tension break). The NTSB could only conclude that the tug pilot had, for some unknown reason, lost control. Other factors were suggested. The similarity between that incident and ours was that each glider pilot pulled the release handle, assumed the rope fell away but ended up with a rope break. That's my reading of the report, but I may have missed something.

Yes, Open Cirrus CG hook failed to release for several pulls. Tow pilot did not respond to positioning far left and wing rocking nor to radio calls. Eventually released after several pulls from the left position with some slack in the rope. Hook was removed and replaced before next flight after showing excessive play on shaft. Until that aero tow, most launches were from winch while I owned the glider.

Frank Whiteley

[Hartley Falbaum[_2_]]

On Thursday, May 14, 2020 at 3:35:18 PM UTC-4, Duster wrote:
> Has anyone heard of or experienced a case where the pull of the glider's release handle during flight failed to result in the rope dropping off the release mechanism? Last summer two of us were under tow when turbulence threw us too high above the tug (or sink drove the tug too low) @~2,000ft agl. One of us remarked that "We need to release", and we each pulled the handles. I pulled mine again at least twice and I distinctly remember the cable moving a few cm each time. We turned away from the tug, but after a few seconds I thought I heard a loud bang accompanied by a slight, transient vibration, but no nose movement. Pulled the handle several more times. First I'm thinking we hit the towplane, but then I saw him below and ahead of us with about 4-6' of rope trailing off his Tost release, then radioed him to report the rope break. An inspection did not reveal any evidence that the rope had gotten hung up on the gear doors, wing or empennage. Testing the release gave the normal rope drop after a few mm's of pull, even under heavy tension. The other pilot didn't hear the "break", but the flight logger did record it as a spike of noise on the trace. Any hypotheses on this one?
>
> Perhaps in a related incident, the 2017 Pawnee fatality accident report where there was intra-cockpit video, the glider pilot reported that (after an admitted distraction) he got high on tow, noticed some rope slack, pulled the dive brakes and released the rope. The GoPro showed almost full deployment of the spoilers, first a short movement of the release cable, followed by a "snapping sound", followed by a longer slack in the cable. The report also revealed a short length of rope hanging from the Pawnee (with a high tension break). The NTSB could only conclude that the tug pilot had, for some unknown reason, lost control. Other factors were suggested. The similarity between that incident and ours was that each glider pilot pulled the release handle, assumed the rope fell away but ended up with a rope break. That's my reading of the report, but I may have missed something.

Our Club had a similar sounding event a couple of years ago. Our Pawnee has the TOST reel system. The glider was a ASK 21. The glider pilot was a long retired airline pilot, recently returned to flying. he was solo in the '21, got distracted, and way out of position. He pulled the release, but no release. He did not recall (or maybe know) the Pawnee had the ability to cut the rope. He decided he had to break the rope and tried. He couldn't. The Tug pilot, a multi-thousand hour duster veteran, was about to dump him, when the rope broke. Fortunately, there was enough height and they both recovered. The release was later checked on the ground and found to be OK. Replaced anyway.
Review of ethics's TOST installation manual and other information disclosed that the TOST release force required for an out of position release may be as high as 45 lb at the handle or knob. That is a much higher force than usual.

Hartley Falbaum

[Tango Whisky]

Le vendredi 15 mai 2020 14:30:26 UTC+2, waremark a écritÂ*:
> I was at the field when a glider could not release. The combination descended back to the airfield with the rope still attached at both ends and landed safely. I understand that if you want to descend with the rope attached the best way to control the descent is with the glider pilot carefully using the airbrakes.

If you want to land on tow, you descend with full airbrakes into the low tow position and keep the airbrakes fully open. The tow pilot is in charge of the approach/descent. It is essential that on short final, he remembers that there is a glider 5 or 7 meters below him...
That's how we teach this here in Switzerland. It's a quite useless exercise, but it's fun ;-)

[[email protected]]

UH: Absolutely relevant, and the suggestion to hold the release open (or cycling once, then hold open) is a good one, particularly if you can't see the rope to confirm as was in our case.

[[email protected]]

We have an E Series Tost (E85) mounted in a very deep, narrow nose tunnel. It has a single closing arm that pivots up. The lower, fixed arm has a channel that the ring will rest on w/o load. Under a no tension condition (e.g., slack rope and/or glider in a 0 or slightly neg G such as in a kiting-recovery maneuver; plus the positive air flow in the tunnel at ~70mph) could possibly result in failure to release. Might test this at altitude.
https://www.dropbox.com/sh/gs2fi5dij30os4q/AADbnUvIvjhYMPVfvBmNY_GNa?dl=0

I can imagine that in some kiting incidents where the glider lowers the nose and creates rope slack (thereby temporarily unloading the tow plane's tail), taking up the slack could produce a sudden secondary pull up on the tail, making things even worse. The upward momentum of the tail would then require more elevator input than might be available.

[Jonathan St. Cloud]

On Friday, May 15, 2020 at 8:22:47 AM UTC-7, Tango Whisky wrote:
> Le vendredi 15 mai 2020 14:30:26 UTC+2, waremark a écritÂ*:
> > I was at the field when a glider could not release. The combination descended back to the airfield with the rope still attached at both ends and landed safely. I understand that if you want to descend with the rope attached the best way to control the descent is with the glider pilot carefully using the airbrakes.
>
> If you want to land on tow, you descend with full airbrakes into the low tow position and keep the airbrakes fully open. The tow pilot is in charge of the approach/descent. It is essential that on short final, he remembers that there is a glider 5 or 7 meters below him...
> That's how we teach this here in Switzerland. It's a quite useless exercise, but it's fun ;-)

When I trained to land on tow at Minden the tow could stop faster than the G103, so it was important for two plane to go left of center line while the glider maneuvered right of center line. Would be embarrassing to resend the tow. After both signaled couldn't release, the glider moved to low tow. It wasn't difficult but should be briefed with both parties.

[Jonathan St. Cloud]

On Thursday, May 14, 2020 at 12:35:18 PM UTC-7, Duster wrote:
> Has anyone heard of or experienced a case where the pull of the glider's release handle during flight failed to result in the rope dropping off the release mechanism? Last summer two of us were under tow when turbulence threw us too high above the tug (or sink drove the tug too low) @~2,000ft agl. One of us remarked that "We need to release", and we each pulled the handles. I pulled mine again at least twice and I distinctly remember the cable moving a few cm each time. We turned away from the tug, but after a few seconds I thought I heard a loud bang accompanied by a slight, transient vibration, but no nose movement. Pulled the handle several more times. First I'm thinking we hit the towplane, but then I saw him below and ahead of us with about 4-6' of rope trailing off his Tost release, then radioed him to report the rope break. An inspection did not reveal any evidence that the rope had gotten hung up on the gear doors, wing or empennage. Testing the release gave the normal rope drop after a few mm's of pull, even under heavy tension. The other pilot didn't hear the "break", but the flight logger did record it as a spike of noise on the trace. Any hypotheses on this one?
>
> Perhaps in a related incident, the 2017 Pawnee fatality accident report where there was intra-cockpit video, the glider pilot reported that (after an admitted distraction) he got high on tow, noticed some rope slack, pulled the dive brakes and released the rope. The GoPro showed almost full deployment of the spoilers, first a short movement of the release cable, followed by a "snapping sound", followed by a longer slack in the cable. The report also revealed a short length of rope hanging from the Pawnee (with a high tension break). The NTSB could only conclude that the tug pilot had, for some unknown reason, lost control. Other factors were suggested. The similarity between that incident and ours was that each glider pilot pulled the release handle, assumed the rope fell away but ended up with a rope break. That's my reading of the report, but I may have missed something.

Distracted on tow! How does that happen? Isn't flying the most important thing you have to do for the first four minutes of flight? Have glider pilots not heard oof a sterile cockpit?

[5Z]

On Thursday, May 14, 2020 at 12:35:18 PM UTC-7, Duster wrote:
> ... We turned away from the tug, but after a few seconds I thought I heard a loud
> bang accompanied by a slight, transient vibration, but no nose movement. Pulled
> the handle several more times.
> ...more stuff snipped ...
> ...similarity between that incident and ours was that each glider pilot pulled the
> release handle, assumed the rope fell away but ended up with a rope break..

In my thousands of flights in a variety of sailplanes, front and back seat, I have *never* not seen the rope disconnect from the glider. I pull the release, observe the rope depart, then maneuver away from the towplane.

Normally, it's a right turn while reducing speed to look for the thermal. In a contest, it generally a left turn. Sometimes, I continue straight while watching the the towplane go away.

As an instructor, I've seen a number of pilots, experienced or not, who seem to automatically begin a turn at the same moment as pulling the release. WTF?!

As with nearly every other aspect of flying, there's always time for the OODA loop - observe–orient–decide–act. First loop is just before releasing to make sure it's safe to release, then the next loop is after pulling the release before making the turn, etc, etc, etc. Each loop may only take a second or two, but should always be happening.

If my release fails, then it fails and the tow continues as if nothing has happened because I'm waiting to see that rope go away. At that point, I'll begin troubleshooting while maintaining a normal tow position. I might try to put some slack in the rope, then pull. I might move to one side or the other and then pull to see if a side load will allow me to release. All this time, I'll be watching for the rope to go away.

If this fails, I'll discuss options with the tow pilot on the radio. Returning to the airport in a descent is probably the best option. Then while above an open area, have the tug release the rope, and then check to see I still have the rope. If I still have it, then I'll be prepared to expect my tire to run over the rope and possibly break it, or just make some noise....

I've done landings on tow and even touch and go while on tow, so that's also an option. But only if I know the tow pilot has done this, or I we can brief the process on the radio while descending.

5Z

[Tango Whisky]

Landing with 40 m of rope tangling from the nose of the glider is a no-event. Just come in 10 m higher, and touch ground with a very light slip.

[Delta8]

Yes but related to being a lazy kid . Our club has the typical rope setup, Schweizer ring on one end and a Tost ring on the other.

It was a rather busy day and I failed to swap ends. At 2000 ft I pulled the 1-26 release and nothing happened , about 2000' ft later the Tow pilot saw me off to the side waggling my wings and released without incident . The rope passed under my nose and the wind resistance released on it's own.

The small Tost ring slid up and jammed the release. Someone actually found the tow rope hanging in a tree and returned it to the airport.