PTT

I was behind a Callair in an ASW-17 when (I learned later) the tow pilot ran a tank dry. The perception from the glider was that the tow plane had stopped in mid air and the glider was catching up really fast. It doesn't take long for the relative drag of a dirty tow plane with a windmilling prop and a clean glider to eat up the 200' length of the tow rope. And it is not a perception that you normally see in a practice PTT but it sure gets your attention fast IRL. Not knowing what the tow plane's problem was, I left him to sort it out and I connected with the wave and went on my merry way.

This is one of the emergency scenarios I tell our club towpilots and CFIGs to discuss and practice. Easy to do - at a predetermined safe altitude, towplane gradually reduces power and starts a gentle descent. If no action from student, then demo a wing rock and/or make a simulated engine failure radio call..

I suggest that the first time a student sees this is as a briefed, "this is what is going to happen" situation. After that, it should be a required no-notice EP (with CFIG agreement).

Just watch out for the tow ring when you release!

And while you are at it, the tow pilot might as well complete a no-power approach to the field - good practice and lets the glider know how long he has before the runway is clear, etc...

Kirk
66

Kirk, even better as a BFR "surprise":

05-22-1999 BFR in G-103A at Minden with M. J. Moore CFI.
On 3rd flight, he said it looked like the lift was starting, so let's take a 2k' tow.
All going OK as we approached release altitude, then we were into 300-400 fpm lift. Then I felt a slow decay of energy in seat of my pants. Tow plane suddenly dropped and my left hand, already on the release, pulled twice quickly and broke the glider away to the right.
CFI Moore and towpilot has conspired to simulate a slow engine failure.
A great, great lesson!

Well trust me, when the plane runs out of gas things get interesting pretty quick. There is no gradual loss of performance.

Towplane @ 70 kph
70 kilometer/hour = 63.794 foot/second
200 foot towrope / 63.794 foot/second
3.135 seconds = 3+ Mississippi which seemed enough in that situation.

07-03-1994 Keystone Gliderport with Tom as CFI for transition to glass.
Towplane backtaxis after hook-up.
Towpilot shouts, "I'm getting pretty low, but I think I got enough for one more."
I pull the plug and shout, "I'll wait."
Could feel Tom's smile on the back of my neck.

In a crisis, you may not rise to the occasion,
But, you will sink to the level of your training.

Thanks, Tom

3.135 seconds implies that the tug will come to a dead stop which is not the
case. The speed should remain about the same with the tug arcing downward.

Once, with a 2-33 on tow, I experienced a blown front seal in the Pawnee
235. The windscreen was immediately coated with oil and the cockpit filled
with smoke. I waved the glider off and spiraled down to land (I try to stay
within gliding distance of the field when towing).

On debrief, I complimented the instructor and student with getting off so
quickly after I rocked my wings. He laughed and said that he could see a
pair of wingtips rocking in a cloud of smoke so he released immediately.

I've made three dead stick landings in tow planes; all successful for the
tug and the glider.

"Roy Clark, "B6"" wrote in message
...
Towplane @ 70 kph
70 kilometer/hour = 63.794 foot/second
200 foot towrope / 63.794 foot/second
3.135 seconds = 3+ Mississippi which seemed enough in that situation.

07-03-1994 Keystone Gliderport with Tom as CFI for transition to glass.
Towplane backtaxis after hook-up.
Towpilot shouts, "I'm getting pretty low, but I think I got enough for one
more."
I pull the plug and shout, "I'll wait."
Could feel Tom's smile on the back of my neck.

In a crisis, you may not rise to the occasion,
But, you will sink to the level of your training.

Thanks, Tom

When doing pre-take-off checks CBSIFT CB and always E(ventualities).
What will I do if the launch fails?
Where will I go after regaining flying speed?

Get it sorted in the brain on the ground before you need it in the air.

We at Dumfries & District Gliding Club have only one runway, a forest to
the East, rough ground to the West, North and South. We have to be very
aware of launch failure procedures and even our very early ab initio pilots
are taught launch failure very early in their training.


David Neilson
Dumfries & District GLiding Club

On Friday, November 22, 2013 6:31:01 PM UTC-6, wrote:
Well trust me, when the plane runs out of gas things get interesting pretty quick. There is no gradual loss of performance.

True. But we are talking about introducing a simulated emergency, not risking a full blown one!

I prefer not to chop the throttle on my towplane in mid tow, and avoid the risk of the tow rings hitting the glider when they release (yes, they will be REAL CLOSE instead of springing away!

That being said, it is useful to discuss the various ways a towplane can fail (gradual, sudden, catastrophic!) during the debrief of the flight. We all do debrief training flights, right?

Kirk