PTT

Had my first genuine PTT yesterday. Not counting a couple of rope breaks that you could see coming. The pawnee had an engine failure at around 6-700ft AGL.

Things get busy fast. The towpilot was busy keeping the pawnee flying and heading for something safe to land on. The student in front initially followed the towplane, using brake to descend. He didn't understand what was going on initially and was just trying to stay behind the towplane. By the time the towpilot called us on the radio to say he had an engine failure he was already descending fast and heading back the the airfield. I pulled the release at the same time he was starting the radio call.

I've seen this before when doing practise PTTs. If the student hasn't been warned they take a second or so to realise the rope is going away. Same when the towplane waves them off. They don't believe what they're seeing for a while. The old brain takes time to process before it reacts.

Luckily the pawnee made it into a nice field, not the riverbed or rough ground that was most of the local area. Nice landing used all the field and ended with no damage hard up against the fence but not actually touching.

All ended with no harm done, but I'm sure a few hearts beat harder for a while.

--
Philip Plane

On Friday, November 22, 2013 3:00:21 PM UTC-5, wrote:
The student in front initially followed the towplane, using brake to descend. He didn't understand what was going on initially and was just trying to stay behind the towplane.

Philip Plane

I had a similar situation with a commercially rated (!) glider pilot getting a local area field check about 10 years ago. To be fair, he wasn't very current/active in gliders (he was flying helicopters for Uncle Sam), but it was pretty shocking to watch. The L-19 was slowly chewing on a valve stem and managed to choke on it at about 800 feet. I immediately saw the climb rate going to hell and was waiting a few Mississippi to see what the guy in front would do. We were rapidly gaining speed as he tried to stay in position behind the now descending towplane. I think the tow pilot was too preoccupied with his own problems to wave us off. When I pulled the release, the guy up front was completely confused. I had to talk him through the fact we had a rope break and that it might be good to set up for landing about now. After we landed, he cried foul as "the towplane didn't wave me off." Needless to say, he didn't pass the check ride.

P3

Had a similar thing happen to our Pawnee. The carburetor float had stuck in the full up (full) position. Repair shop said "This happens all the time!"

New float is made of plastic so it is slippery in case it touches the float chamber side wall.

We require our tow pilots to disconnect the tow rope at the end of the day by actuating the release knob.

Tom Knauff

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

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

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