dt@spice.cs.cmu.edu (Dean Thompson) (10/31/85)
Brent's suggestion that maybe the Caravan's pilot was prevented from recovering airspeed on engine failure by a mass movement toward the rear exit sounds to me like a very plausible theory. I would like to see someone who has data on some of the more common jump planes and who knows enough about aeronautics sit down and figure out what IS going to happen in case of engine failure soon after takeoff, and come up with some recommendations on how the jumpers should respond at various altitudes. For example, it may be that below 1000 feet jumpers in a plane such as the Caravan with a rear exit should move towards the front of the plane and not try to exit, while above 1000 feet (or some altitude) all but the rearmost person(s) should move towards the front while those at the rear open the door and jump. The others could then move back a few at a time and jump. Obviously I'm making this up as I go along, and I personally have never been in a Caravan, but it does seem as though there should be SOME procedure for each plane. I have an unrelated question for the group. I currently have 21 jumps and am doing 20 second delays on T-10's. We are taught NEVER to try to cut away under any circumstances -- in fact the instructor tries to avoid even having the students know where the capewells (is that how you spell it?) are. The idea is that it is far more likely that a student will panic and cut away from a minor malfunction and/or cut away too slowly and too low. Instead we are supposed to manually deploy the reserve (which has no pilot chute) by throwing it down and away from us, and into the direction of the spin if we are spinning. Recognizing that capewells are a relatively slow and tedious way to cut away (two motions with both hands), and that serious malfunctions on a T-10 are very rare, this procedure still worries me. Does anyone know how safe it is to deploy a round reserve (with relatively short lines) while under a Mae West on a T-10? How about a streamer? Dean Thompson dt@spice.cs.cmu.edu
kas@hp-pcd.UUCP (kas) (11/05/85)
I believe Dean has made some extremely insightful (is that a word?)
points. Although nobody will ever know, I'd bet anything that the pilot was
not able to control the Caravan because of a mass shift to the rear of the
plane. We already know that that is what happened to the Loadstar. It had too
many bodies bunched up in the rear, and when it stalled it was too tailheavy
for the pilot to regain control--even after several of the jumpers got out
and lightened the load. Deans' suggestions belie his relative newness to the
sport. I think it would be a good idea to have a standard procedure worked
out that would give the pilot a fighting chance to save the plane and some
lives. The key point is BALANCE. If too much weight gets too far back, the
plane ain't gonna fly. For that reason, the ONLY time anyone should be at the
rear of the plane is when they are lining up at the door. If it's a big plane
and is dropping more than one group, those that aren't exiting should be
scrunched up as far forward as possible to help offset the mass of bodies that
is bunched up at the rear door. Don't move rearward until the first group
is gone. In the case of aircraft problems, regardless of altitude, Deans'
suggestions of keeping everybody forward probably IS the best solution. The
pilots' first priority is to get the plane into a stable glide, then and only
then can the jumpers exit in an orderly (but hastily) manner, if altitude
permits.
OK, now some comments about cutting away T-10's. I was taught the
same philosophy as Dean -- that is, "Something over my head is better than
nothing, so don't cut away until the reserve is hand deployed". With a pilot
chute-less reserve, it is generally possible to hand deploy alongside a T-10
with no problem. BUT, there are a couple of exceptions. If the 'functioned
main is spinning wildly, a cutaway IS necessary because the reserve will wrap
around it like a barber pole if you don't. A slowly spinning 'function need
not be cut away first, as long as the reserve is thrown in the direction of
spin. The other situation where a cutaway is mandatory is when the canopy
is snagged on the airplane. Fortunately, this rarely happens, but I did see
it happen once. The jumper in tow MUST MUST MUST cutaway before dumping the
reserve, otherwise all hell will break loose. Therefore, it is MANDATORY
that all jumpers know where those capewells are, and how to use them. Also,
high wind, water, or tree landings may require releasing the capewells.
With a high speed malfunction, such as a streamer, the reserve should
be thrown with both hands as hard as possible away from you. Never throw it
straight down, or it will rise up and wrap around you. You want to get it as
far out as possible so that it won't rise up into the main, either. With a
slow malfunction such as a Mae West, the skirt of the reserve canopy should be
grasped with both hands and snapped in the breeze like a bedsheet. This will
ensure that the canopy is "big" enough that it won't rise into the main when
you let go. The reserve is always packed so that the skirt is on the right
end of the container, just under the ripcord handle, so you'll always know
where it is. I know this method works, 'cause I've had to employ it.
A word of caution though. Presumably, since you've made over 20 jumps,
you will be buying your own gear soon. When you "graduate" to the more hi-tech
gear, you will HAVE to cutaway a bad main. Thus, when you make that step into
more modern gear, get EXTENSIVE training on cutaway procedures, until you can
do it in your sleep. I don't just mean have someone TELL you how to do it, I
mean DO IT many times from a suspended harness. You CANNOT hand deploy a
reserve safely if your main is a garbaged PC or Square canopy. Besides, you'll
probably have a piggyback rig, so you can't reach the reserve anyway. Ideally,
you should buy a rig that has single point release (i.e., 3-ring release) which
requires a single motion to accomplish a cutaway. If you buy an older rig for
your first rig, make sure it at least has the 1-1/2 shot capewells. They can
be safely cutaway, (they were used successfully for years), but they aren't as
fast as a 3-ring release system.
*
/ \
|---/---\---| Ken Scofield C-9355
| Gone | Hewlett-Packard PCD
| Jumpin' | Corvallis, OR
|-----------|
{ucbvax!hplabs, harpo, ogcvax}!hp-pcd!kasmsb@link.UUCP (Mike S. Balenger x8789) (11/05/85)
I have been in the Caravan. It *was* nice. The rear door was wide enough for 4 across. Maybe five. It stayed open all the time. Therefore, opening the door was not a problem for exiting the plane. The plane was just very low. In a high speed crash like that, the G-forces experienced in the cabin would probably have been too great to get hold of anything with which to propel one's self out the door. *********** In reference to deploying a reserve before cutting away: While I was an undergrad in Virginia, I orginized classes for a drop zone. One of the guys in the class had THE WORST T-10 MALFUNCTION anyone on the drop zone had ever seen. Many of them were old-timers in the sport. The malfunction was just a line over which had caught a wad of material on top of the canopy, causing a high (but not lethal) decent rate, and a 1-2 second spin. The part of this that I think is important is that the WORST malfunction that they had ever seen was not lethal. Had the student ridden it in, and performed a good (granted, a REAL good) PLF, he could have walked away from it with no broken bones or twisted ankles. Students there had also been taught not to cut away. Instead, they were taught to throw their reserve "down-and-out at a 45 degree angle in the direction of a spin." When this student tried to do it, it didn't work. Pictures taken of him with a telephoto camera seemed to show him holding onto it so that it couldn't catch the air. He said that it kept blowing up in his face, and he couldn't get it out into the wind. Who is to say wether the student panicked, or the rate of decent was too low to really catchh the reserve chute. In either case, after 2500 feet of attempts the reserve finally inflated at about 200 feet, and took enough weight off the main that the main cleared. He landed under two perfectly good parachutes. This incident has always raised some intersting questions for me: -- Is it naive to believe that students can correctly execute complex sequences to deploy a reserve? -- What would he have done if his spot wasn't as good as it was? You can't steer two parachutes. -- Would it have been reasonable to cut away the main after the reserve had inflated? What would have been the risks of the main fouling the reserve on its way out? -- Is a relatively slow malfunction like this really fast enough to catch a reserve without a pilot chute, and get it out? If not, a cut away seems appropriate. -- Do jumpers panic so much that they would really hold on to the material of a chute? If so, a cut away seems inappropriate. -- Why aren't Steven's cutaway systems used on more conventional gear? (A Steven's cutaway system is really quite simple. It automatically pulls the reserve ripcord when the main is cut away. It also prevents only one main riser from being cut away, a condition which could cause a streamer. It consists of a piece of webbing which attaches the two main risers and the reserve ripcord. If one of the main risers is cut away, it will not fly away and cause a streamer because it is attached to the other main riser. When the other main riser is cut away, it cuts away the main chute, and pulls the pin of the reserve as you drop away from it. Thus, with a Steven's system, if you only cut away one side, you are no worse off than you used to be. True, you are only suspended by one riser, but you are suspended. If you cut away both sides, your reserve is automatically opened into clean air-- guaranteed.) ******* Happily, the ole T-10's are a dieing breed. The new student squares are safe, dependable, and more fun. They will win in the long run. The one-shot cut away and reserve deployment is much easier to teach and execute. The only drawback could be in altitude awareness, but I think this is an easier thing to teach. What does anyone else think about conventional gear, reserves, Steven's or the like? How 'bout the letter to the editor of Parachutist which advocated a gas or rocket deployed reserve? Post comments here! -- ihnp4!link!msb Michael S. Balenger (201) 949-8789
atlas@haddock.UUCP (11/13/85)
During an aircraft emergency, especially under 1000 feet, skydivers SHOULDN'T MOVE AT ALL. Changing the center of gravity of the aircraft pretty much prevents the pilot from doing anything useful about recovering. In a case where recovery might have been possible, moving around can change a scary event into a disaster. Pilots know about flying planes and skydivers know about flying their bodies. If you have confidence in your jump pilot, do what he says in an emergency, don't ad lib. If you don't have confidence in him, get another jump pilot. Your emergency procedures are correct for your type of equipment. Capewells have a lot of problems, including large things hanging where they can snag the lines of a canopy you are trying to get rid of and the distinct possiblity of only releasing on one side. Hand deploying works, I've seen it. Don't hand deploy under a streamer, though. I know you must have been taught pull and punch. Alan Atlas ima!haddock!atlas