Spin

Bill Daniels wrote:

Perhaps someone familiar with the incident could explain why the pilot tried
to turn back from a height of 80 meters. I would expect that, with a wire
break at 80 meters, the pilot would have 75% or more of the airfield
straight ahead for a safe landing

Stress? Overtax? Panic? Blackout? It's happened before.

Stefan

Stefan wrote in message ...
Bill Daniels wrote:

Perhaps someone familiar with the incident could explain why the pilot tried
to turn back from a height of 80 meters. I would expect that, with a wire
break at 80 meters, the pilot would have 75% or more of the airfield
straight ahead for a safe landing

Stress? Overtax? Panic? Blackout? It's happened before.

Stefan


The commentator says:

"Sunday afternoon in Magdenburg.
It was a routine start with winch, but at 80m the cable breaks.
For the pilot this crash ends with a couple of cutting wounds"

The glider is a 2-seater DG500. Probabbly with only the pilot on
board.
The commentator's voice is very professional. A story by the media for
the general public?. Not very good for our sport.
If standard rules (e.g. landing straight ahead after this low cable
break) had been performed nothing seriously would have happened. And
why did the cable break anyway (weak cable, heavy glider, to steep a
take off, to much force on the cable by the winchman and what have
you).

Karel, NL

If standard rules (e.g. landing straight ahead after this low cable
break) had been performed nothing seriously would have happened.

What are the standards altitudes for such incident? Here are the list
I learnt: 50 straight landing, 50&100 one 180 degree turn, 180 two
turns or small circle. Of course in strong wind I would increase these
values.


/Janos

There are no worldwide standards but rather local procedures (depending on
the terrain) with daily adjustments (depending on wind conditions).

--
Bert Willing

ASW20 "TW"


"Janos Bauer" a écrit dans le message de
...

If standard rules (e.g. landing straight ahead after this low cable
break) had been performed nothing seriously would have happened.

What are the standards altitudes for such incident? Here are the list
I learnt: 50 straight landing, 50&100 one 180 degree turn, 180 two
turns or small circle. Of course in strong wind I would increase these
values.


/Janos

Bert Willing wrote:

There are no worldwide standards but rather local procedures (depending on
the terrain) with daily adjustments (depending on wind conditions).

--
Bert Willing

ASW20 "TW"

"Janos Bauer" a écrit dans le message de
...

If standard rules (e.g. landing straight ahead after this low cable
break) had been performed nothing seriously would have happened.

What are the standards altitudes for such incident? Here are the list
I learnt: 50 straight landing, 50&100 one 180 degree turn, 180 two
turns or small circle. Of course in strong wind I would increase these
values.


I had a reminder last summer during a check flight on a new field, and
then tried to pass the message to my first students during my first flights
as instructor: as long as landing straight ahead is possible, do it, don't
try anything else. If it is not possible, then you should have a height
sufficient for an abbreviated pattern. What I would like to add is some
rule of thumb for estimating if landing straight ahead is possible, not
based on looking on instruments if possible, like "First push the stick
in order to reach a normal flight attitude and speed. Then if you can see
the last 300m of the runway, you can land ahead". The value of 300m is
of course subject to discussion and change. The advantage of such a strategy
is that it could be well planned before take-off by having a well-known ground
feature mark the point you must see for deciding to land straight ahead.

Janos Bauer wrote:

What are the standards altitudes for such incident? Here are the list
I learnt: 50 straight landing, 50&100 one 180 degree turn, 180 two
turns or small circle. Of course in strong wind I would increase these
values.

I have been VERY surprised a few times by the effect of a slight
tailwind on my rope break practice. Since then I pay a lot
more attention to when the towplane rotates. If he rotates
much further down the strip, then I know I have either
a tailwind, heavy glider, high density altitude, etc.

Of course this assumes the towplane pilot rotates at the same speed
each time (in my experience they are very consistent).

In the cases when this happens
I know we ain't doin' very much "up" for the amount
"forward." So I SWAG a higher 180 altitude (maybe 300 or 400 feet).
The worst was an open canopy L-13 with two people on a hot
day with a 3-5 knot tailwind and only 180hp towplane. I dunno
if even 400 feet AGL woulda been enough.

Anybody else use the point of towplane rotation as
a hint?

I've wondered why airliners don't have some spot on the
ground (GPS) some distance down the runway, and abort
at that spot if they haven't reached a certain airspeed.
Seems simpler than doing all them calculamications for
wind, density altitude, etc. which may have changed since
you did them. Why not observe instead of predicting?

It doesn't work if you have ice/frost on the wings,
or if the ASI malfunctions (reads too high AS),
or you're misconfigured, but otherwise it seems to make
sense to me...

Of course when's the last time anybody de-iced a towplane or
glider, for goodness sakes! ;O

Mark, I think Janos was talking about winch launch. The land ahead/turn
height for winch launch depends greatly on the winch site although at 25% of
the altitude expected without a wire break, say 500 feet or 150 meters, a
landing straight ahead on the runway should be possible. The ideal,
available at most sites, is an overlap between the two options where a 360
degree turn with a landing into the wind can be made from 300 feet AGL and a
straight ahead landing can be successful at 450 feet.

For airtow, there are certainly conditions where a low altitude rope break
will not allow the glider to get back to the airfield. Tailwinds, high
density altitudes and heavy gliders make conditions worse for rope breaks.
I have often been at 1000'AGL (300 Meters) before I felt comfortable about a
return to the runway. Under these conditions, airtow weak link strength
becomes a life or death matter.

Conditions like these make me far more comfortable with winch launch where I
can be sure of landing the glider on the airfield without a scratch.

Bill Daniels


"Mark James Boyd" wrote in message
news:4023f76a$1@darkstar...
Janos Bauer wrote:

What are the standards altitudes for such incident? Here are the list
I learnt: 50 straight landing, 50&100 one 180 degree turn, 180 two
turns or small circle. Of course in strong wind I would increase these
values.

I have been VERY surprised a few times by the effect of a slight
tailwind on my rope break practice. Since then I pay a lot
more attention to when the towplane rotates. If he rotates
much further down the strip, then I know I have either
a tailwind, heavy glider, high density altitude, etc.

Of course this assumes the towplane pilot rotates at the same speed
each time (in my experience they are very consistent).

In the cases when this happens
I know we ain't doin' very much "up" for the amount
"forward." So I SWAG a higher 180 altitude (maybe 300 or 400 feet).
The worst was an open canopy L-13 with two people on a hot
day with a 3-5 knot tailwind and only 180hp towplane. I dunno
if even 400 feet AGL woulda been enough.

Anybody else use the point of towplane rotation as
a hint?

I've wondered why airliners don't have some spot on the
ground (GPS) some distance down the runway, and abort
at that spot if they haven't reached a certain airspeed.
Seems simpler than doing all them calculamications for
wind, density altitude, etc. which may have changed since
you did them. Why not observe instead of predicting?

It doesn't work if you have ice/frost on the wings,
or if the ASI malfunctions (reads too high AS),
or you're misconfigured, but otherwise it seems to make
sense to me...

Of course when's the last time anybody de-iced a towplane or
glider, for goodness sakes! ;O

Bill Daniels wrote:
Mark, I think Janos was talking about winch launch. The land ahead/turn
height for winch launch depends greatly on the winch site although at 25% of
the altitude expected without a wire break, say 500 feet or 150 meters, a
landing straight ahead on the runway should be possible. The ideal,
available at most sites, is an overlap between the two options where a 360
degree turn with a landing into the wind can be made from 300 feet AGL and a
straight ahead landing can be successful at 450 feet.

Aha! An excellent point. I hadn't considered the advantages of
the steep climb from ground-launch and the increased options it
provides. Thanks for pointing this out (since ground-launch is
rare in this part of the gliding community i.e. west coast USA).

On 2/6/04 1:22 PM, in article 4023f76a$1@darkstar, "Mark James Boyd"
wrote:


I've wondered why airliners don't have some spot on the
ground (GPS) some distance down the runway, and abort
at that spot if they haven't reached a certain airspeed.
Seems simpler than doing all them calculamications for
wind, density altitude, etc. which may have changed since
you did them. Why not observe instead of predicting?

We can't afford not to do both, Mark. The calculations would still be
required in every case, making the "spot" different for each takeoff.

Airlines conduct operations on many different runways under all conditions
of weather, ambient lighting, loading, runway slope, braking coefficients,
etc., and many of these factors will vary from flight to flight even at the
same field, on the same day, in the same aircraft. In some cases a crew
member may fly in as many as three or four variations of a single type
(e.g., DC-9-10, DC-9-30, DC-9-40, DC-9-50), with a significant range of
performance and handling characteristics, within the same 24-hour period. I
think you can see that calculations for each flight with go/no-go decisions
made according to predetermined speeds for the anticipated conditions, with
adjustments when conditions change (there's your "observation") is the only
way we can safely operate.

With hundreds, or thousands, of pilots on the roster, and scores or hundreds
of destinations across the country and around the world, the idea of trying
to train every pilot to the visual cues at every runway would leave the
training department using far more assets than the revenue side of the
operation could likely produce.

I'd much prefer to make split-second decisions based upon the well
understood performance of the aircraft, than on the often vague cues
provided by the environment in which we operate the aircraft. In contrast to
the typical sailplane flight, we operate big fast moving machines often
under conditions in which I would prefer not to have to walk to my car, let
alone drive it to the airport.

If visual cues are to comprise the primary reference for takeoff
performance, by all means let it be at 30 to 50 mph in a 1-26 or in a
Pawnee, on a sunny day from 2500 feet of grass, where I am familiar with
every bump and soft spot, and not from the cockpit of a 180,000 lb
(relatively light, at that) Boeing 757 on a snowy February night from 6500
feet of wet runway at Midway, on the south side of Chicago.

Flying sailplanes well, I suspect, will be complicated enough.


-----
Jack
-----

Jack wrote:
On 2/6/04 1:22 PM, in article 4023f76a$1@darkstar, "Mark James Boyd"
wrote:

I've wondered why airliners don't have some spot on the
ground (GPS) some distance down the runway, and abort
at that spot if they haven't reached a certain airspeed.
Seems simpler than doing all them calculamications for
wind, density altitude, etc. which may have changed since
you did them. Why not observe instead of predicting?

We can't afford not to do both, Mark. The calculations would still be
required in every case, making the "spot" different for each takeoff.

OK, then both. From my point of view, however, if I had to choose
between 1. point on the ground and ASI and timing to acceleration vs.
2. just look at the engine gauges and interpret them, I'd take #1
first.

http://www.avweb.com/news/safety/182403-1.html

Airlines conduct operations on many different runways under all conditions
of weather, ambient lighting, loading, runway slope, braking coefficients,
etc., and many of these factors will vary from flight to flight even at the
same field, on the same day, in the same aircraft. In some cases a crew
member may fly in as many as three or four variations of a single type
(e.g., DC-9-10, DC-9-30, DC-9-40, DC-9-50), with a significant range of
performance and handling characteristics, within the same 24-hour period. I
think you can see that calculations for each flight with go/no-go decisions
made according to predetermined speeds for the anticipated conditions, with
adjustments when conditions change (there's your "observation") is the only
way we can safely operate.

Yep. So add in a calculation for time to airspeed. And add in
a calculation for ground distance to airspeed. If one detects
that the acceleration and airspeed aren't coming up at that point,
abort the takeoff (presumably that point is calculated to be
the point of safe abort).

The simplicity of this is one doesn't need to deal with the complexity
of diagnosing what CAUSED the lack of acceleration. Was it the
RPM or the EPR that was wrong? Is it the RPM or that the prop is
worn thin? Did I leave the hand brake on for takeoff? Is the
nosewheel flat? Did they put a second passenger in the glider and
now it's too heavy? So many factors (some known, some not).
I prefer simplicity...

Of course the simple answer is just to have much more power
available than you could possibly need (RJs with 8000fpm climb,
a nice 400hp stearman) so really I'm talking about using this
as a tool to provide the same level of safety with less training
and less cost, rather than improving safety...

With hundreds, or thousands, of pilots on the roster, and scores or hundreds
of destinations across the country and around the world, the idea of trying
to train every pilot to the visual cues at every runway would leave the
training department using far more assets than the revenue side of the
operation could likely produce.

Umm...I didn't say anything yet about visual cues. GPS, a stopwatch,
and marking the point when the takeoff roll starts. For jets,
an automated calculation and "low acceleration" warning
light.

For towplanes, probably a visual cue is easier, though,
and simpler than for an airline, because one tows off the same field
again and again. Another possibility is to simply walk the
field (or taxi up the taxiway) with the GPS and measure the
visual cue distance and the safe takeoff runway.
I've used GPS to measure a short strip before and declined to
takeoff there. Useful things, these little gadgets. Better than
my golfing range estimating eyeball...

If I towed out of a farm field or a "new to me" airstrip, and
I had some questions about whether I could make it over the
power lines, I might use this technique as an "extra tool in my bag"
to improve my confidence and capability. How much does the 1" thick
soft dirt slow me down? Am I light enough on fuel? I can do all
the calculations, but it's never the things I know that hurt me,
it's the things I don't know that I don't know...


If visual cues are to comprise the primary reference for takeoff
performance, by all means let it be at 30 to 50 mph in a 1-26 or in a
Pawnee, on a sunny day from 2500 feet of grass, where I am familiar with
every bump and soft spot, and not from the cockpit of a 180,000 lb
(relatively light, at that) Boeing 757 on a snowy February night from 6500
feet of wet runway at Midway, on the south side of Chicago.
-----
Jack
-----


The last time I even dreamed that an airline pilot looked out
the window was at Ontario in low overcast when the tower called

"Delta XYZ traffic 2 O'clock 1 mile below you an experimental
with no transponder tight left base will pass behind you..."

And a real nervous co-pilot "XYZ looking for traffic"

....and I suspect a few expletives from the captain
"Who lets a f***ing no-squawk ragwing fly around in OUR
go***mn airport?"

Again, for any airline guys, I wouldn't DREAM of asking you
to look outside the cockpit for a visual cue of anything.
(Now, now, don't get yer panties in a bunch, I'm jus'
hasslin' ya, with yer umpteen item checklists, and yer
bells and whistles, and yer big cozy pilot chairs, and
yer Datsun 280Z's :PPP)

For you guys, I just thought maybe a nice shiny new
"acceleration" computer might be an extra takeoff tool... :P
Something to go with the pre-calculated trim settings and
"gee ya almost hit the tail" printouts?

But you are right, perhaps try it a while in the pawnee towing
an extra heavy ballasted two seat glider a few times first
and see how it affects the rotation point, and then
come up with some takeoff abort scenarios, and see how
much runway you REALLY have.

I actually really also liked the discussion about how longer
towropes allow an abort where the glider doesn't ram into the
back of the tug, too...