On Tuesday, November 12, 2013 11:22:14 AM UTC-5, son_of_flubber wrote:
With the dewpoint at 15d F. today, I'm ready to heat things up. Regulations on aerotow ropes vary by region. What is the evidence to support the various approaches? PTT (Premature Termination of Tow)(aka rope break) correlates with a number of fatal accidents. How often has a hard_to_break towrope led to a fatal accident? Options to land after a PTT vary by airport and can be non-existent at certain altitudes. Why is an extra strong towrope not an option where the straight-ahead landing option is poor or non-existent? In what year did the FAA set the FAR for towropes and what was the quality of towropes at that time? (obscure, but interesting question). At the airport where I am towed, the same towrope satisfies the FAR for both the frequently towed heavier two-seater, and my less frequently towed lighter weight single place glider. Does this mean that the two-place is more likely to break the towrope?

There are no regulations that vary by region, but practices may vary in different operations.
I personally have never heard of an accident caused by a rope that was too strong. Over the years there have been a few accidents caused by rope breaks at low altitude and at least one fatality that I recall out west. Whether this was due to selected rope strength or wear, or both, I don't know.
All failures of ropes at our operation are at the time of initial acceleration when a worn rope that has not been inspected fails at the ring. Stronger ropes tend to reduce the liklihood of this happening in my experience.
Avoiding the use of short ropes is a good way to help ensure long tow pilot life. Errors in glider positioning are magnified by short ropes.
Long, strong, inspect.
FWIW
UH