During an email exchange on GBSCtalk in 2005, a member did some pencil and paper calculations and expressed the belief that a turn back to the runway could be made with as little as 100 feet of altitude. He also mentioned that the excess tow speed could be converted to altitude. Several instructors responded that neither of these choices would be a wise.
Some of the reasons are
- The "oh, shit factor", where it takes the pilot 3 or 4 seconds for the reality to set in and actually do something. I've seen *much* longer reaction times. Your speed will be gone.
- Pilots may initiate a shallow banked turn. They know they need to crank it but are afraid of steep turns at low altitudes (especially under pressure) and so they don't. I’ve seen more of those than I like.
- We're not talking about a 180 if the break happens on the extended runway center line - we're talking a 225 followed by a reverse 45.
- Given the rope break on the extended center line, you won't be arriving directly over the threshold but rather from the side where there may be obstructions.
- You not only need to get turned around, you may also need to travel some distance to get to the threshold. This may be a problem on a hot humid day (see below).
- Even when things go pretty well, a release at 225 ft, at times, has put some pilots closer to the trees than they were comfortable with.
- Converting kinetic into potential energy is dangerous. You are reducing the margin over the stall. Coupled with the panic factor that may be present, the pilot may over rudder (skid) to get the nose pointing toward the landing area, resulting in a spin.
- If the speed is slow, any appreciable wind gradient at a low level could put the upper and lower wings in differing airflows. This could result in an uncontrollable roll due to high angle of attack and reduced aileron effectiveness.
Yes, on a perfect day on a perfect field with a perfect pilot, 100 AGL may get you back - but that's not reality. The risk of not making it means striking the ground with a wing tip during a steep turn - resulting in a cart wheel that you will NOT walk away from. Going into that orchard (rwy 34), wings level and at low speed, pointing the nose between the trees so that the wings absorb the impact energy, is soooo much preferable. The insurance company will own the aircraft, but you'll walk away, and that's the ultimate goal.
Remember that the 200 ft call out is the minimum that we require.
Much better is, every few seconds decide that if the tow fails now, I'm going to [fill in the space]. That way when it does happen, the decision has already been made, saving time. I'm reminded of a story where a veteran carrier pilot lost an engine on a cat shot and he instantly ejected. After he got pulled out of the water, a junior pilot asked him how he had reacted so fast. The response was "Son, I made that decision 18 years ago".
After you callout "200 feet", you can *think* about returning. Remember that in many wind situations, 200 feet may not be enough or too much. - How can 200 feet be too much? Consider a 35 knot headwind on take off where you are at midfield (more or less) at 200 ft. A 180 will give you a up close and personal view of I190 at a ground speed that will get your attention.
- How can it be not enough? A slow climb on a hot humid day may put you beyond gliding range of the field.