Recognizing and reacting to tow plane engine failure

On Thu, 23 Oct 2014 09:14:09 -0600, BobW wrote:

In thinking more about the possibility of a gradual loss of engine power
(e.g.
throttle creep), I concluded it could perhaps be one of the trickier
things for Joe Glider Pilot to detect should it happen (say) before or
immediately after becoming airborne. Never happened to me, but there's
good reasons for mentally preparing for how to recognize and deal with
"the abbie-normal on-tow possibilities."

Slightly OTT, but: At my club field a favourite winch-driver sport, when
asked by an instructor to "simulate a power fade at 500 ft" has been to
slowly reduce power until the glider is being dragged up the field at a
constant height and waiting to see how long it takes for the student to
realise what's going on and release.

Just like Bob describes when on tow, initially its quite hard to
distinguish a genuine winch power fade from a winch driver driver failing
to compensate for a drop in wind speed on a gusty day - about the only
clear distinction is the length of time that the situation persists
without correction.



--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On 2014-10-23 16:08:39 +0000, kirk.stant said:

On Thursday, October 23, 2014 9:41:57 AM UTC-5, son_of_flubber wrote:
It would be useful to hear your stories of how incidents of tow plane
engine failure turned out for you. It seems that there is very little
time to recognize, react, and recover. What are classic mistakes to
make in this scenario?

Would it be useful to practice 'release and land to the side of the tow
plane path' (and have the tow plane fly a normal departure of course)?
Any other recommended training exercises?

Your training should have covered these eventualities before your checkride.

As a glider pilot, I've had a towplane run out of fuel (at top of tow -
we both released at the same time, rope never recovered), towplanes
abort takeoff due to canopy door slamming open on ground (Pawnee), and
at least one PTT (not towplane related). All were interesting but well
within what was covered by my training.
From the towplane perspective, I've briefed and given sumulated
emergencies to student glider pilots - such as briefing the glider
pilot to slowly extend his divebrakes (at a safe altitude), note the
difference in climb, then watch for my rudder waggle signal to close
them. I've also done practice engine failure on tow (again,
prebriefed) by slowly retarding the throttle at the top of the tow, and
giving the waveoff wing rock to the glider, so the glider experiences
the sensation of the tow losing power, and sees the "release now"
signal.

If you are properly trained, have a plan, and pay attention, there is
always plenty of time to take the correct action. If you are not sure
you are ready, I suggest some practice scenarios with a cooperative tow
pilot and instructor.

My funnest one: it's often quite humid here, and the canopy will fog up
as soon as you close it, and unfog once you start moving on the takeoff
roll. Until one day it didn't. When I got to liftoff speed and still
couldn't see anything past the tail of the tug I released and rolled to
a stop. Got out and found the front seat control for the vent in the
nose was closed. Opened it, pushed back to the takeoff point (with the
trial flighter still buckled in), and tried again. This time the canopy
cleared as expected.

So that's another item I now check every time I buckle a trial-flight
person in, along with turning on the master switch, turning down the
vario, and checking the transponder setting.

My first glider instruction flights were in 1967 (off a winch) but most of my flying since then has been aero-tow.

In many hundreds of aero-tows (I haven't checked my logbook for the actual number), I have had two complete tug failures and one partial loss of power.. The first was obvious as the tug prop stopped rotating instantaneously from a dropped valve just as I became airborne. I was unable to stop before the tug (heavy 19 m ballasted glider)and landed safely alongside it. The second was virtually the same, although power loss was more gradual. the third was a non-event - I just released.

I have never experienced a rope break while airborne, but have had a couple of hairy landings when give a simulated rope break at or below 200-feet.

I still wonder why we put so many folks at risk with this exercise?

Mike

Simulated rope breaks at 200ft is a lot like practicing bleeding...

Boggs

On Thursday, October 23, 2014 10:41:57 AM UTC-4, son_of_flubber wrote:
It would be useful to hear your stories of how incidents of tow plane engine failure turned out for you. It seems that there is very little time to recognize, react, and recover. What are classic mistakes to make in this scenario?

Would it be useful to practice 'release and land to the side of the tow plane path' (and have the tow plane fly a normal departure of course)? Any other recommended training exercises?

In a little over 2,000 launches, I've had 2 actual towplane failures. In both cases, the failure was gradual, with no obvious puff of smoke or stopped prop. The problem signs were a gradual decrease in climb rate until we were barely climbing at all. The obvious difference between just flying through heavy sink (which is not uncommon at a mountain or ridge site) is the change in attitude of the towplane and the obvious need to pitch down to stay behind the now struggling towplane. The most memorable of these was behind an L-19 that was slowly gobbling up a valve during a tow on a bodacious ridge day. My good friend was towing, and he nursed us around the airfield in a close in pattern climbing at barely 100fpm, allowing a safe landing at any point. When he got me to 1,000 feet AGL, he waved me off and brought the sick L-19 in.

FWIW... we practiced exactly this scenario in our instruction program at my old club. We would brief the mission with the towpilot, who would slowly back off the power starting at around 600 feet. I did this with at least a half-dozen students, and with most of them it would go something like this: Student:"Hey, what's the towpilot doing"? Me: "What do you mean"? Student: "We've stopped climbing" Me: "So, what are we going to do about it?" Student: "But he didn't wave me off..." It was pretty eye-opening to think that students might follow the towplane down if the towpilot was too busy to wave him/her off. The post-flight debriefs were usually quite enlightening.

P3

On 10/23/2014 9:18 AM, wrote:
On Thursday, October 23, 2014 8:41:57 AM UTC-6, son_of_flubber wrote:
It would be useful to hear your stories of how incidents of tow plane
engine failure turned out for you. It seems that there is very little
time to recognize, react, and recover. What are classic mistakes to make
in this scenario?

Would it be useful to practice 'release and land to side of the tow plane
path (and have the tow plane fly a normal departure of course)? Any
other recommended training exercises?

A simple answer. Save yourself first. I have been on both ends, but not at
once. If YOU have a problem don't expect the other guy to fix it. Don't
kill the other guy. If he has a problem, you have no way to fix it. So,
take the best way out for you. Typically this put into go left or go right,
but I would suggest that this makes little sense. It depends entirely on
where you are and what's in the way. Rope failure - not the towplane's
problem. Keep flying the towplane. Towplane failure - not glider's problem
- let towplane fix it by staying out of his way.


I'll second this succinct feedback. Flying's real safe so long as you don't
hit nuthin'...'cept the earth in a controlled manner!

Bob W.

On Thursday, October 23, 2014 8:30:05 AM UTC-7, firsys wrote:
So there are tuggles (new word) who are insensitive
to change in engine note and do not monitor the tach!
No surprise, unfortunately.
JMF

The tuggies I know, including myself, haven't yet lost *all* their self preservation instinct and are keenly attuned to the performance and nuances of "their" machine. I take off with left hand holding throttle forward, ready to go for the release. But in truth, most of my attention during the take off roll is the take off roll, with brief scan of engine instruments to affirm all is well after throttle advance, rotation speed approaching where and as it should, and a few quick glances at the mirror to be sure the glider is tracking okay. I worry less about the engine than about the glider behind me. If Mr. Motor is going to try and kill you, it usually gives warning, albeit brief. If the glider tries to do you in, my understanding is there can be almost no time to recognize and react.

Sometimes Minden conditions get sporty, often with wave rotor it can take most of the tuggies attention just flying the plane. My biggest concern remains a glider kiting, especially with a CG hook. Happened once at maybe 30 feet. Mistook it for turbulence and reacted accordingly with stick. Fortunately for me the glider pilot recovered quickly, regaining position before I ran out of elevator or had a tail stall - - apologized to me afterwards. The line guy said, "He went way up, didn't you see that?!" Nope, clueless I guess.

bumper
MKIV & QV

When I'm flying at the front of the rope, I'm concerned for both me and the glider. I don't know a tuggie who isn't.

I've experienced simulated power failures and simulated rope breaks just after I'm flying but the tow plane isn't.

The rope breaks were a piece of cake, as the bang alerts you that something just went wrong and you instantly transition to landing mode.

The simulated tow plane power failure was not a piece of cake. It took a few seconds to figure out that something was wrong, find the release and transition to landing mode.

I think simulated tow plane power failure is definitely something you should see at least once (with an instructor in the back seat to keep you safe, of course)! You'll never forget it, and recognition will come faster if you ever have to deal with it in real life.

-John, Q3

I've never had a tug fail while in my glider but I've had two engine
failures with gliders behind me and one after the glider released.

My position on my own engine failure is this: If I have the time, I'll
get you to a safe position and wave you off. Failing that, and I have
the time, I'll wave you off. Failing that, I'll pull the release and
find a safe landing spot for the tug; you're on your own.

I'm more concerned about the glider who gets way out of position. I
towed for over 25 years before dumping a glider. Hope I don't have to
do it again.

Dan Marotta

On 10/23/2014 8:22 PM, Papa3 wrote:
On Thursday, October 23, 2014 10:41:57 AM UTC-4, son_of_flubber wrote:
It would be useful to hear your stories of how incidents of tow plane engine failure turned out for you. It seems that there is very little time to recognize, react, and recover. What are classic mistakes to make in this scenario?

Would it be useful to practice 'release and land to the side of the tow plane path' (and have the tow plane fly a normal departure of course)? Any other recommended training exercises?
In a little over 2,000 launches, I've had 2 actual towplane failures. In both cases, the failure was gradual, with no obvious puff of smoke or stopped prop. The problem signs were a gradual decrease in climb rate until we were barely climbing at all. The obvious difference between just flying through heavy sink (which is not uncommon at a mountain or ridge site) is the change in attitude of the towplane and the obvious need to pitch down to stay behind the now struggling towplane. The most memorable of these was behind an L-19 that was slowly gobbling up a valve during a tow on a bodacious ridge day. My good friend was towing, and he nursed us around the airfield in a close in pattern climbing at barely 100fpm, allowing a safe landing at any point. When he got me to 1,000 feet AGL, he waved me off and brought the sick L-19 in.

FWIW... we practiced exactly this scenario in our instruction program at my old club. We would brief the mission with the towpilot, who would slowly back off the power starting at around 600 feet. I did this with at least a half-dozen students, and with most of them it would go something like this: Student:"Hey, what's the towpilot doing"? Me: "What do you mean"? Student: "We've stopped climbing" Me: "So, what are we going to do about it?" Student: "But he didn't wave me off..." It was pretty eye-opening to think that students might follow the towplane down if the towpilot was too busy to wave him/her off. The post-flight debriefs were usually quite enlightening.

P3

Dan, I understand. I'd just note that (1) you know two glider pilots who've experienced engine failure, and (2) these were airborne situations. I was talking about ground run engine failure, which I saw happen twice (but not as a glider pilot). I also have seen a near ground (15 foot altitude) rope failure. So I know I should be prepared to handle them.

Glider pilots and tow pilots have an iron-clad covenant that should be talked about, not just silently acknowledged: You do your very best not to kill me, and I'll do my very best not to kill you. Towing is a unique thing in aviation, it's serious business, and it needs to be constantly recognized as such.

Getting out of position on a tow is a cardinal sin for a glider pilot. I know of two people (not me) who did it over the last 10 years. Repercussions were swift and severe, as they should be. Sometimes, though, it's very difficult to stay in position - I've towed out of Minden and Blairstown through rotor on wave and ridge days when this was the case. In those flights I've been ready on the release, and I'd bet the tow pilot was ready on his release, too.

-John, Q3

On Friday, October 24, 2014 12:11:01 PM UTC-4, Dan Marotta wrote:
I've never had a tug fail while in my
glider but I've had two engine failures with gliders behind me and
one after the glider released.

My position on my own engine failure is this:* If I have the time,
I'll get you to a safe position and wave you off.* Failing that,
and I have the time, I'll wave you off.* Failing that, I'll pull
the release and find a safe landing spot for the tug; you're on
your own.

I'm more concerned about the glider who gets way out of position.
I towed for over 25 years before dumping a glider.* Hope I don't
have to do it again.