TOST vs. Schweizer Hooks on Tow Planes.

A CG hook and high tow is a recipe for disaster. I only have CG on my Dg200, no problem at all with low tow.
We don’t allow anything other than Tost here, thank goodness.

Why is CG and high tow a bad thing???

Originally Posted by

" The push back will be the cost of the Tost system"
Push back is not about cost, push back is about the lack of information on legally installing the Tost system on all current towplanes in light of you wanting the FAA to ban all Schweizer hooks. As I said to you last time this came up, if you want to make towing safer collect and make available STCs and successful 337s for Tost hook installations. Instead of whining to a higher power for a solution that screws clubs be the solution that helps clubs.

Your characterization of my "whining" to a higher power speaks of one unconcerned with safety. I pointed out clearly the glaring knowledge of a problem which has resulted in the death of tow pilots. The FAA AO acknowledges the problem as does the SSA/SSF (which is a joke). The SSA is a toothless tiger along for the ride while collecting dues and selling magazines in my Constitutionally protected opinion. The FAA has the teeth if they choose to chew.

I'm more concerned with saving lives than anything else having been a second or two from losing mine. If your mechanics can't find the appropriate STCs and 337s perhaps you need to find another mechanic.

I've been contacted by one tow pilot who has acknowledge my actions which influenced his facility to make the changes I recommended. By his acknowledgement it saved his life shortly thereafter. I've heard from commercial operators who experienced this event and realized the potential. They did the work needed to make the changes to a safer, more accessable system.

Have a nice day.

Walt Connelly
Former tow pilot
Now happily flying Whirlybirds.

Originally Posted by

Mr. Connelly, for my own knowledge where does the 1500/1200 lb. limitation on the Schwiezer system come from. Ive tried to find a reference in the past but couldnt find one.

To respectfully add to the debate, I'd challenge anyone in favor of ousting the Schwiezer system if they feel the same way about aero tow with a Tost c.g. hook? Here the superior Tost system has been perhaps miss used and this installation has caused more glider accidents and fatalities than Schwiezer release on tow plane accidents.
I appreciate the position of the "hands off" crowd, what I'd like to see is if those in favor of banning the Schwiezer system on the tow plane also believe they should be beholden to a regulation or policy affecting the method by which they are towed in their glider (when it's their expense).
These two items would have the single biggest impact on soaring safety that I can think of at the lowest cost and highest participation level if it were either a regulatory or insurance requirement. The problem is pilots are cheap and nobody thinks it will happen to them.

-Doug

The Schweizer hook is limited to a 1200 lb rope which by the 80-200 rule would limit the max gross weight of the glider in tow to 1500 lbs. This came from the Schweizer factory recommendations. You could use a stronger rope but would have to then use a weak link of appropriate strength. I believe the Tost system has a limit of 900kg which is just short of 2000 lbs covering most all current gliders. Any supplier should be able to supply you with the pertinent published limitations. Wings and Wheels would be a good source.

I don't follow you on the Schweizer vs Tost system regarding accidents. I have not seen those statistics, perhaps you could site them? I will say that in 7000 tows I have never had a problem with a CG hook glider but then again most of these are flown by more experienced pilots. It will be the student on solo or occasionally an older pilot who should no longer be flying who will upend you.

Walt Connelly

You don’t mention what type of fleet you have. Putting a Tost tow hook on a Pawnee, Super Cub or Husky is very simple mechanically and paperwork wise.

On Wednesday, May 1, 2019 at 12:02:59 PM UTC-4, Paul Agnew wrote:
Does anyone know the limits on these STC'd hooks? They claim to be better than Schweizer hooks, but don't list any numbers to substantiate it. (I've emailed an inquiry to them.)

https://pacificaerialtowhooks.com/

I just heard back from Pacific Aerial Towhooks.

#1200 glider weight limit using AC 43.13-2B, 804(d). Their release handles look to be at least 5:1 by design.

PA

On Monday, April 29, 2019 at 1:37:55 PM UTC-7, Jason Scott wrote:
Currently operating 3 tow planes, all with Schweizer hooks installed. I would love to get access to some concrete information on the issues with the Schweizer hooks, comparison between the two, and any concerns with the TOST system. My goal is to likely switch over the fleet, having personally experienced a situation with a glider losing directional control on tow, and causing momentary upset to the towplane. In my opinion, the TOST system is superior, and tangible information is the best way to present this opinion to the other parties involved in our operation.

Pacific Aerial Tow Hooks has an FAA approved STC with a hook that has lower release forces than the Schwitzer hook. The tested release load on a new PATH hook is only 56 lbs with a 1000 lb tow load at 20 degrees. The whole kit is STCed on a wide variety of aircraft.

On Wednesday, May 1, 2019 at 9:02:59 AM UTC-7, Paul Agnew wrote:
Does anyone know the limits on these STC'd hooks? They claim to be better than Schweizer hooks, but don't list any numbers to substantiate it. (I've emailed an inquiry to them.)

https://pacificaerialtowhooks.com/

Paul as I replied to your email,
The pacific Aerial Tow Hook is rated for a limit load of 1440 lbs. using AC 43.13-2B, 804(d) the glider can be 1200 lbs or a banner can be 720 lb, (although we recommend a banner limit of 600 lb.) The rope for glider towing is limited to 960 lbs breaking strength.

The geometry of the Schweizer hook has a load ratio on the release of .377 and the PATH tow hook has a load ratio of .265, so the release loads on the Schweizer are 42% more. Also the ring is held in one location and can't move around like the Schweizer hook.