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I was the safety officer at a glider operation earlier this year and we had a new tow pilot who forgot to drop the rope. By radio, I instructed him to drop the rope before landing. The downsides of this is that it would temporarily leave the rope in the middle of the grass field where an aircraft might run over it, and also someone would have to golf cart out to retrieve the rope.

Later, when he found out about it, the chief tow pilot got angry about this and said the tow plane should have landed with the rope attached and dragged it back to the launch location. I thought this was unwise because this could damage the rope, or if the rope were to catch on something as the plane landed, it could have dangerous consequences for the tow pilot. Also, I have seen loose tow ropes whip around. Considering that there is a metal buckle at the end of the rope, imagine that thing whipping around. If the plane landed with the rope attached, I was picturing that buckle whipping into a bystander or a parked plane.

Of course, the third possibility is that he could do a go around, fly all the back and do the rope drop correctly. The disadvantage of this is that it would delay the return of the tow plane for another 10 minutes while he did the go around, and we had multiple people waiting for tows.

What is the best procedure?

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    $\begingroup$ As a non-glider pilot, my instinct is to notice that all of the drawbacks from the first ones are safety related whereas the last one is logistical. Based on that, it seems to me that the circuit and controlled drop would absolutely be the most wise procedure. $\endgroup$ – Dan Aug 9 '17 at 16:33
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    $\begingroup$ As a glider pilot, I have already seen the end of a dropped rope (the metal ring normally attached to the tow plane) that had penetrated roughly 30 cm in soft soil, and imagined the consequences of replacing this soil with someone's head. So there are also some risk associated with that drop. Of course, it is not dangerous if the drop occurs far from anyone, but I can imagine the temptation of dropping it "closer" to the ground crew. $\endgroup$ – Quentin Aug 9 '17 at 16:53
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    $\begingroup$ Place I flew gliders out of always dragged the rope. I never saw it dropped. $\endgroup$ – zeta-band Aug 9 '17 at 17:38
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    $\begingroup$ @J.Hougaard That is not true. In most cases the entire rope has a failure rating. Sometimes, when a lightweight glider is flown, there is attached a "weak link" to reduce the rope's rating, however, even in that case it would be preferable to use a lower-rated rope rather than a weak link. In any case, the rope involved was a normally rated rope with no weak link. The rope holds with sufficient force that if it caught on something solid while the tow plane was landing, it could cause a serious problem. $\endgroup$ – Tyler Durden Aug 9 '17 at 18:06
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    $\begingroup$ Agreed with @zeta-band -- I flew gliders for 8 years at a field on the northern edge of KPHL's mode C veil and never saw a towplane (purposely) drop a rope for a non-emergency. We operated out of a grass field surrounded by trees on most sides (maybe 10 miles south of KCKZ) and never had problems with towplanes landing with the rope attached. When I first arrived, SOP was to put a wiffle ball on the tow rope so that "flew" behind the towplane a little better and had some more protection on the ground, but that was dropped without much issue a few years later. $\endgroup$ – Marius Aug 9 '17 at 18:54
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To start: I flew gliders for 8 years at a field on the northern edge of KPHL's mode C veil and never saw a towplane (purposely) drop a rope for a non-emergency. We operated out of a grass field surrounded by trees on most sides (maybe 10 miles south of KCKZ) and never had problems with towplanes landing with the rope attached.

There are some factors here that feed into this. That particular field (http://www.pgcsoaring.com/) has generally well taken care of and is a completely turf field. I think we added some lime markings to denote a landing box on our usual landing runway, but that's about it. I have a picture of the runways used for normal operations below. Takeoffs were started on the far right on runway 25 (picture has been rotated), and landings, typically, were facilitated on the runway marked by a dashed line.

PGC landing ops on runway 25

Now, something that isn't quite clear from the overhead views are the trees. At the far right hand side of 07-25, you have a stand of trees (and two hangers) that go up 40-50 feet. Landing over these, particularly with a tow line, can put you out in the boonies if you want to make sure that the tow line isn't dragging through the trees. The FAA Glider Flying Handbook (https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/glider_handbook/media/gfh_ch12.pdf) indicates that a tow 200 rope can "fly" about 130 feet below a towplane, so clearance in that dimension is critical. The pictured field actually has 3 operating runways (07-25, 01-19, and 13-31) and, on the approach to each (save 25), there are no trees near the runway threshold or the runway is situated at the top of a significant hill.

Insofar as ground abrasion goes, I'd see wear and tear on a towline over time, but it was relatively slow accumulation. Slow enough that you could track it by rope checks at the weak link (if in use) and tow hook prior to each flight...which you are probably doing anyhow. We always had a spare rope spliced and on a reel so that an in-use line could be quickly replaced during normal operations (maybe a minute or less during a regular takeoff if it was coordinated well). But that's more or less semantics: the point is, for the turf field we had, which was well-cleared of rocks, branches, or man-made debris, there were no problems with dragging a rope over the ground provided that pilots and line crew were doing the routine safety checks that they would be doing regardless. Not dropping a tow line also kept down non-airplane vehicle traffic on the field during operations (i.e., it eliminated the need for another runner to get the tow line, especially when aircraft are anticipated to be landing).

The Glider Flying Handbook has this much more to say about landing with a tow rope (GFH 12-10):

Landing with the tow line attached is not prohibited by regulation; however, the following points should be considered:

  1. Obstructions are cleared by more than the tow line length (altimeter lag considered).

  2. The field is well turfed. It is simply inviting early tow line failure from abrasion to land with the tow line on hard ground or paved runways. Landing with the tow line should never be attempted unless the field has clear approaches and is at least 2,500 feet in length.

Other situations require the tow line to be dropped, normally in the glider launch area, during short approach to the runway. If the tow line is to be dropped, the tow pilot must be constantly aware of the launch area situation. The tow line drop area must be defined and ground personnel must be briefed and aware of the drop area. Ground personnel must stay clear of the drop area, and the presence of an individual in the drop area requires an immediate go-around by the pilot of the tow plane without dropping the tow line.

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Perennial debate. When I towed, at my annual checkout, I was required to drop the rope. There were several times that I did drop the rope, but 98% of the time, I landed with the rope. All the ops people knew where it was, I knew where it was, and the other tow pilots knew where it was.

Besides, normally we were charged with getting to the ground quickly to get another tow up. So full authority slips, etc. all resulting in a steep approach with no danger of hitting the trees at the perimeter of the airport.

From my perspective there are risks either way, and I prefer not dropping anything prior to landing. For one thing, it takes time, and when 3 or four planes are towing, and there are gliders recovering, and now tow planes have to come in for a low pass to drop the rope, it gets even more chaotic. Chaos precedes stupid things happening.

The tennis ball trick is nice, but I just used a short streamer of surveyor tape. It kept people busy trying to figure out the color code (pink, orange, green, chartreuse, fuscia, you name it. I heard all kinds of theories, but each morning, I would just pick a 2 ft section of one tape or another from my trunk. Or let some young kid decide.

That streamer got more attention to where the rope was, though.

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    $\begingroup$ I highly second the comment of "chaos precedes stupid things happening." I cannot agree with that enough. $\endgroup$ – Marius Aug 9 '17 at 20:21
  • $\begingroup$ You can drop the rope while on short final right at the start of the runway. You'll be landing upwind anyway and turning back around for the glider to get hooked up. It does require a wide enough field for the drop zone to be away from the prep zone. $\endgroup$ – ratchet freak Aug 9 '17 at 23:18
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    $\begingroup$ @ratchetfreak near the start of the runway are the people preparing for flights, and gliders being queued, often on both sides of the runway. That would not be a safe place for the drop. When I drop, I do a low pass, and drop the rope in the center of the runway, then go around and land after a circuit (4 min). For example, I might land long, while another tow is hooking up at or near the threshold of the runway. $\endgroup$ – mongo Aug 10 '17 at 0:57
  • $\begingroup$ @mongo that's why I mentioned the wideness of the field so an area can be reserved for the drop. $\endgroup$ – ratchet freak Aug 10 '17 at 6:51
  • $\begingroup$ @ratchetfreak perhaps at your operation, but not at the one I towed at. It would absolutely be unsafe to drop at the threshold of the runway with operations going on. $\endgroup$ – mongo Aug 10 '17 at 11:35
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To add another datapoint, I flew gliders in Argentina for 15 years, in many airfields (both club operations and competitions with up to 80 gliders) and I very rarely saw a rope dropped by a tow plane. Our club often did 30 to 40 tows per day on weekends, so it would have made a big difference to have to retrieve the rope each time. Wear and tear from dragging during the landings was not a big issue; we had to replace ropes from time to time, but it was a very uncommon thing to happen as long as we avoided knots to stay on the rope.

I also flew for a few years in western Canada, where dropping the rope seemed to be the standard, even in fairly remote places where it was easy not to hit anything.

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I have seen glider clubs do both. My preference is toward dropping the tow rope prior to touchdown, then having a recovery crew bring it back to the launch site in order to prevent abrasion and or grinding debris into the fibers causing structural damage. It also prevents damage to the line or the aircraft in the event the rope snags obstructions during rollout. Conversely, leaving the tow line attached does facilitate quicker turnaround time for the towplane allowing for multiple glider launches in minimal time.

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