Aerosoftware - skydiving


by Jan Meyer

Spotting tends to be the most difficult skydiving skill to acquire by most jumpers. There are many reasons why spotting is difficult. There can be a lot of people depending on a good spot. You may put too much pressure on yourself and your ability to spot accurately disappears. You may not like looking at the ground. Spotting may distract you from your exit and the rest of the dive. You may never have taken enough time to really understand how spotting works and give yourself some practice at it.

Spotting starts on the ground. The best way to spot is to know what point on the ground is directly below your desired exit point. Suppose there are no winds on the ground and aloft. What is the "spot"? The "spot", that place on the ground, is your landing area. It's the peas, the landing field, the place you want your feet to touchdown. You must exit when the plane is directly over the peas, the landing field or the "spot".

If there are winds, surface and aloft, then you must also take these into account. The basic idea is to get out upwind of the landing area. The stronger the winds, the further upwind you need to get out. This means you need to identify a physical object on the ground that is upwind of the landing area and is visible and readily identifable from altitude. Upper winds also change the aircraft's ground speed. Jumpruns are normally into the wind. Thus, stronger winds aloft will give an aircraft a slower ground speed on a jumprun into the wind. It will take longer for an aircraft to travel across the ground.

Most DZs have typical "spots" for normal weather conditions. Ask the best spotters (these aren't always the best jumpers) where the spot is. They'll tell you something like "get out over the alligator farm" or "get out over the numbers" or "get out over the hanger" or "etc...." They usually mean you should be exiting over these points, not starting a long and laborious climbout. Verify this by asking where you should call the cut and start the climbout. They'll then point out some more landmarks for you.

Use the landmarks and other plane loads to observe how spotting works. Watch an aircraft at altitude from the ground. Where does the plane turn on to jumprun? What is the plane's ground speed? What is the plane's flight path? Where is it headed? Where do you see corrections to its flight path? Where is the cut given? Where do jumpers exit? Where do the groups open? Is their spot good?

Hopefully, when you do all of this, you will notice that the actual flight path of the plane was over the three landmarks you'll be using for cut, climbout and exit. You should also notice that a good spot can be anywhere within a quarter mile or so of a perfect spot. This means that you have room for error. Now you're ready to board an aircraft and "spot" your load.

You have three landmarks chosen before you ever leave the ground. Landmark one is the cut, two is the start of the climbout and three is the exit. Now how do you get the plane to fly over these landmarks and throttle back for a cut?

You and your pilot must communicate before you leave the ground and on jumprun. On the ground ask your pilot which way jumprun is or request a specific jumprun. In the air you must use visual signals to communicate with your pilot. Shouting "5-RIGHT -CUT" is absolutely worthless in aircraft with wind and engine noises. Besides this, "CUT", "LEFT" and "RIGHT"all sound the same to your pilot. Remember he's wearing a headset and possibily even earplugs. Visual signals are a must for good spotting. If you must relay signals to the pilot, make sure your relay person also uses visual signals. You don't want your corrections to be misunderstood because someone else didn't use hand signals.

Jumpruns start away from the DZ. You don't need to give corrections on the base leg before jumprun or even on jumprun if you're 5 miles out. Wait until you're less than two minutes and preferably less than one minute out from the spot. Most pilots throttle back on jumprun when they get close to the spot. They may or may not throttle back to a full cut, but they usually slow the aircraft's airspeed from full flight. You should realize that this means you're close enough to give corrections. Also watch your ground speed decrease.

Before any corrections can be given you have to know where you are going. Then you must determine if where you are going will get you where you want to be (over the spot). You must watch the aircraft's groundtrack to determine where you are going. You must look straight down! It's best for the plane to be in straight and level flight because you can use your sense of balance to help determine "straight down". Whenever the plane is in a turn, your sense of balance tells you "down" is toward the aircraft floor. Your eyes tell you down is at an angle to this. To avoid confusion, make sure the plane is flying straight and level.

Check the wingtips' relationship to the horizon to determine if the plane is in a turn. If one wingtip is below the horizon and the other is above it, then the plane is in a turn. If both wingtips have the same orientation with respect to the horizon, then the plane is flying straight. Check the aircraft's nose or tail for roll. If the tail or horizontal stabilizer are at an angle with the horizon, then the plane is in a turn. Use your sense of balance too. When straight down through the floor lines up with what your eyes tell you is straight down, then the plane is flying straight. Use this technique only as a backup or last resort. Bad weather, turbulent air, blocked sinuses or hypoxia can "fool" your sense of balance.

Once you are convinced the plane is flying straight and level (or climbing). You must look straight down for several seconds and observe the plane's ground track. This is the path along the ground that the plane is flying over. Once you have determined the ground track, you must project it forward in a straight line along the ground to see if it passes over the spot, see Fig. 1.

Actual aircraft ground track used to project future ground track.Fig 1: Actual aircraft ground track used to project future ground track.

If the plane's present course will pass to the left of the spot, then you must correct the flight path to the right, as shown in Fig. 2.

Aircraft ground track that will pass to the left of the spot.Fig 2: Aircraft ground track that will pass to the left of the spot.

If the plane's present course will pass to the right of the spot, then you must correct the flight path to the left, as shown in Fig. 3.

Aircraft ground track that will pass to the right of the spot.Fig 3: Aircraft ground track that will pass to the right of the spot.

The desired outcome of corrections is to change the plane's ground track so that it will pass over the three landmarks for cut, climbout and exit. Corrections are given in increments of five degrees. There are numerous ways of doing this. If your aircraft has light signals, you only need to hit the light until you see the plane turn, then let up on the light. If you need more than a five degree turn, then hit the light again. If your aircraft is a small one or does not have light signals, you should ask your pilot which handsignals he prefers or use signals that leave no doubt in the pilot's mind as to which way a correction should be made.

A nearly fool-proof technique is to give a "five" signal by opening and shutting your fist and then point, almost dramatically, in the direction you want to turn. Avoid waving your thumb or finger back and forth. This is confusing and really indicates that you don't know what you're doing. (Hopefully, this isn't the case.) If the jumprun is perfect or close enough, you don't need to do anything. An OK hand signal or thumbs-up may be nice to give, but it may be interpreted as a correction signal by your pilot. (I only mention this because it happened to me once on a perfect jumprun, that was misaligned when a pilot thought my OK was a correction signal.)

You've corrected the flight path, if neccessary, so that the plane will soon fly over the cut, climbout and exit landmarks. Call a cut by cutting your throat with your hand, a universal signal. Listen for a cut, if the plane is still at a high airspeed. Wait for the aircraft to slow down. This is especially important for larger aircraft. A common mistake is for new spotters to call a cut and scramble out the door. It takes a few seconds for the pilot to respond with his controls and a few more seconds for the plane to slow. You should take this into account by giving a cut several seconds before reaching the climbout landmark. Use this time to take a deep, relaxing breath. Call the cut a little bit early. Keep watching the ground track and ground speed. Then call for a climbout. The cut and climbout are really two distinct events. Some spotters separate them in time by a few extra seconds. Other spotters allow only a minimum of time between them. They allow just enough time for the aircraft to slow and nothing more. When the upper winds are really strong, the aircraft's ground speed will be slower than usual. You may want to wait even a few seconds before proceeding with a climbout. After the climbout, it's time to exit.

Climbouts vary. This is the greatest variable and most unpredictable variable in all of spotting. Use your best judgement to guess how long a climbout will take. Less experienced jumpers tend to take a longer time to climbout, but not always. Seasoned jumpers can be speedy, average or slow-pokes. The exit follows the climbout, regardless of how long the climbout took. A good exit point really depends on your guess on how long the climbout takes. If you're spotting and unsure of how long the climbout will be, ask for a "jam-up" while you're on the ground. You should get a good idea from that.

A great spot is when you know before taking off, your three landmarks for cut, climbout and exit, and approximately how long the climbout will take. You must use hand or light signals for accurate communication with your pilot. Look straight down to accurately observe aircraft track and ground speed.

Spotting is really not hard to do, but it is hard to learn. The large number of variables makes spotting hard to learn. You need to pay attention to surface and upper winds, aircraft track and ground speed, guestimate climbout times, communicate to the pilot and remember your role in the upcoming skydive.

"It is by presence of mind in untried emergencies that the native metal of man is tested"-James Russell Lowell
Originally published in Sport Parachutist's Safety Journal V2, #1 Sept-Oct.. 1989.
©Copyright 1989, 1996 by Jan Meyer. Republished with permission.

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