ericber 0 #1 March 14, 2004 Who's Going to Spot? How often have you been in the situation where someone has asked, "Who's going to spot?", and at that point you made sure eye contact was avoided with the person asking the question? Sound familiar? Knowing how to determine the exit point of an aircraft is the responsibility of every skydiver. If you are not comfortable with the thought of looking out and determining where to exit, I suggest you try it and make yourself learn the art of spotting. Spotting is a skill that must be developed. Reading about spotting takes care of the theory, but does not replace the practical application. The following are guidelines to take into consideration when determining where and when to exit any aircraft. Taking the time to follow these steps will lend itself to building self-confidence about your spotting abilities, as you and others on the plane trust your judgment. There are several very important factors that need careful consideration when determining where to exit an aircraft. 1. Preparation Time (Prep Time): Very important and too often the maker of a bad spot. All too often the point of exit for your group, and the groups that follow, take longer than anticipated. Guess what? You are walking. When you think the exit point is too short, and feel you should wait that extra ten to fifteen seconds, begin your climb out. The time taken here is exactly what Prep Time is. Waiting the additional time lends itself to a long spot. Climb out usually takes longer than you think. You may be surprised when you realize how far the aircraft travels across the ground in ten seconds. The next time you are in a DC-3 look out the door and make sure you are looking straight down. Find a heading on the ground and count to ten seconds. See how far the aircraft has traveled. Use this mental picture when calculating Prep Time. A DC-3 will cover a considerable distance across the ground in ten seconds traveling at a speed of 80KTS or 92MPH. Compare the distance traveled when you repeat the same exercise the next time you are in a Twin Otter, Cessna or local DZ aircraft. Use the mental picture of the distance traveled across the ground when determining the point of exit. Using this technique on high upper wind days could prevent a potentially dangerous situation when jumpers from two groups cross into each others airspace during a track. A skilled spotter will take Prep Time into consideration for all groups on the pass. Load the aircraft in such a way as to allow easy exit for each of the groups on a pass. Determine the experience level of each group on the aircraft so you can take into consideration the time necessary for climb out and exit. Lower experienced groups will take longer to climb out. Each group on a pass should, without exception, allow a minimum of 10 seconds before exiting the aircraft to allow for adequate separation between groups. Always put the highest opening jumper out last. Remember: a) When arriving at the DZ watch other groups exit to give yourself a mental picture as to where the exit point should be. b) Find out who the spotter was on a load that recently landed and ask them what the upper winds are doing, and where the spot is. c) Communicate with the pilot. Don't expect the pilot to know how you want jump run flown. 2. Upper Winds (Free-Fall Drift): While climbing to altitude ask the pilot how fast the upper winds are blowing at altitude, and from which direction the upper winds are coming. The information is easily obtained from Flight Services. *(See Footnote) Depending on the pilot, you could get a couple of different responses. For example you may be told, "The winds are 25 out of 36," or in a less cryptic tone, "The winds are blowing at 25KTS from the north." The former is a compass heading. 0 degrees or 360 or 36 all indicate the winds are from the north, and 18 or 180 indicate the winds are from the south. Knowing what the winds aloft are is critical. The technique in knowing how far to take the aircraft upwind to allow for Free-Fall Drift takes time and repetition. If in doubt ask a more experienced skydiver, who you know can be trusted, to look over your shoulder. When you arrive at the DZ watch another group exiting to see how much 'Free-Fall Drift' or push they get. Upper winds blowing at >50KTS can cause drift of up to a mile or more if exit altitude is 13,000'. Look at the following example: The rate of speed at which an aircraft travels across the ground is known as the Ground-speed. The speed at which an aircraft travels relative to the air is called the Air-speed. Ground-speed and Air-speed are two factors not to be confused. The discussion here focuses on the speed the aircraft travels across the ground as rated in knots. The distance across the ground for one knot is approx. 6080'. Suppose an aircraft is traveling at 75KTS. With no upper winds, the aircraft’s ground speed is 75KTS, or 126.7 feet/per/second across the ground. The aircraft is carrying three groups. Group 1A is a 10-Way, Group 1B is a 6-Way and Group 1C is a 4-Way. The upper winds are minimal; under 10KTS. If Group 1B takes a 6 second delay before exit the horizontal distance between Groups 1A and 1B will be approximately 760'. Sounds like a lot, doesn't it? Now assume the upper winds are blowing at 30KTS. The aircraft is flying directly into the upper winds. The ground-speed of the aircraft is reduced to 45KTS, or 76 feet/per/second. Horizontal separation between groups is reduced from 126.7 feet/per/second to 76 feet/per/second. Group 1B only allows 5 seconds for separation time after Group 1A has exited the aircraft. Using the factor of 76 feet/per/second, the horizontal distance between Groups 1A and Group 1B is approximately 380'. Horizontal separation of 380' is dangerous, especially when you take into consideration the distance covered across the ground during a track. For this example, lets assume Group 1A's break-off altitude is 3,500'. A skydiver in a max-track position can achieve horizontal speeds up to 60MPH, or 52KTS. If a skydiver were to start tracking between 3,800'-3,500' and hold the track until 2,500' (approximately 6 seconds), then flair, waveoff and pull, the skydiver could achieve an average of almost 88 feet/per/second, or approximately 528'. The result would be the potentially dangerous situation whereby one or more skydivers from different groups on the same pass could possibly cross each others airspace. Taking this example a step further, assume the upper winds are now 65KTS. The air-speed of the aircraft remains constant at 75KTS, however, the ground-speed (distance the aircraft travels across the ground) has been reduced to 10KTS, or 16.9 feet/per/second. Based on this example, taking up to 45 seconds before Group 1B exits is not excessive in an effort to gain adequate separation and avoid a potentially dangerous situation. Canopy collisions can and do kill skydivers. 3. Body Position: Face forward and look towards the front of the aircraft. If you are new at spotting do not sit sideways to the door; sit facing forward. Pitch your head sideways and look straight down. Now look up toward the wing tips followed by scanning the horizon. Doing this will help you determine whether or not you are looking straight down and if the aircraft is flying level. Continue to do this motion of looking down, wing tips, scanning horizon and looking down. Compare the horizontal axis of the wing to the horizontal axis of the horizon. Are they horizontally relative to each other? Are they at an equal plane? A couple of degrees off can be a mile or more, especially when the upper winds are blowing. Know if you are looking straight down. 4. Forward Throw: Depending upon aircraft type, Forward Throw carries a group a considerable distance. Take Forward Throw distance into consideration when exiting aircraft such as a DC-3, C-130 or higher airspeed type of aircraft. Although the transition sweep from horizontal throw to vertical decent is a short distance in time, the distance across the ground can add up. 5. Ground Winds: There are times when ground winds exceed the upper winds. Factor into consideration the ground winds in addition to the upper winds for determining the spot. Maybe you will have to take some additional Prep Time allowing the groups to remain up wind of the target. For student and novice jumpers recently off of student status, and depending upon the exit altitude, throwing a Wind Drift Indicator (WDI) may be necessary to help determine the push of the ground winds. Spot for the ground winds when they exceed the uppers. 6. Type of Reserve: Never overlook the skydiver having a round reserve. If you are spotting make sure you take into consideration the person with the round reserve. Learning to spot takes time and repetition. The next time someone asks, "Who is going to spot?" say, "I will." (Footnote) *In many geographic areas Flight Services can be contacted directly for upper wind conditions. Contacting Flight Services directly is not inappropriate for determining upper winds prior to the first load of the day.Blue Skies Eric Bernstein D-9298 [email protected] Quote Share this post Link to post Share on other sites
sortiarius 0 #2 March 14, 2004 Thanks for the post. We were talking about proper spotting skills yesterday at "Safety Day" at the DZ. Quote Share this post Link to post Share on other sites
ericber 0 #3 March 14, 2004 Thank you for the kind words. Realize, there will be folks who disagree and not understand, so be prepared. When my work was published in Parachutist you would not believe some of the comments with respect to the distance an aircraft covers across the ground relative to when to exit. That is the key.Blue Skies Eric Bernstein D-9298 [email protected] Quote Share this post Link to post Share on other sites
piisfish 135 #4 March 15, 2004 Quote6. Type of Reserve: Never overlook the skydiver having a round reserve. If you are spotting make sure you take into consideration the person with the round reserve. how common is that in North America ?? in Switzerland, never seen any except for special occasions like round jumps...scissors beat paper, paper beat rock, rock beat wingsuit - KarlM Quote Share this post Link to post Share on other sites
jumpinjackflash 0 #5 March 15, 2004 Great article, should go in the Articles section of the site.It's a gas, gas, gas... Quote Share this post Link to post Share on other sites
USPA 0 #6 March 15, 2004 Good article, I do have some comments though. QuoteAlways put the highest opening jumper out last. Best not to mix spotting instruction with exit order instruction, although closly related, a different discussion (an FS-4 cameraguy probably opens higher than the skydivers behind him) Quote When arriving at the DZ watch other groups exit to give yourself a mental picture as to where the exit point should be. Be very carefull about using this technique, a ground view of exit point can give a very distorted view, because you don't have any references up there. It can be a usefull tool, but be carefull with it. QuoteFind out who the spotter was on a load that recently landed and ask them what the upper winds are doing, and where the spot is. Must DZ's have the ability to take a look at de uppers and lowers on the ground, use this! QuoteCommunicate with the pilot. Don't expect the pilot to know how you want jump run flown. On the preparation of the jumprun, make sure you can have contanct with the pilot! On the Cessna C-208 for example you're view (and communication) with the pilot can be blocked by jumpers getting upright. QuoteNever overlook the skydiver having a round reserve. If you are spotting make sure you take into consideration the person with the round reserve. Round reserves (In the Netherlands at least) are so rare, that it's the guy jumping it his responisibilty to inform the spotter about his reserve. On a twin otter for example the first groups will exit too short for a round reserve, while the last groups will exit too far. If there isn't a round reserve on board, don't spot for it, we have square's now...The trouble with skydiving; If you stink at it and continue to jump, you'll die. If you're good at it and continue to jump, you'll see a lot of friends die... Quote Share this post Link to post Share on other sites
billvon 2,435 #7 March 15, 2004 Good article; I gave a talk at safety day about how to check the spot and determine when it's safe to get out and when it's not, and there seemed to be a lot of interest. I think that in general spotting isn't covered much in student programs. Some minor points: > With no upper winds, the aircraft’s >ground speed is 75KTS, or 126.7 >feet/per/second across the ground. Note that that is 75 KTAS, or 75 knots true airspeed. A plane travelling at 75 KTAS will actually show 62 knots on its airspeed indicator since the airspeed indicator reads lower at higher altitudes. >Always put the highest opening jumper out last. I agree here, but also would point out that you still have to ensure adequate horizontal separation. People have high openings, high speed mals and long snivels, and that can quickly negate any vertical separation. It still makes sense to put the higher openers out last since it adds a bit of separation under normal conditions, and the high openers are the ones that can make it back from a long spot. Quote Share this post Link to post Share on other sites
chuckbrown 0 #8 March 15, 2004 My home DZ runs a S/L student program with all round reserves. I don't know how common this is with other small DZs, but I would suspect that many DZs don't want to spend the money to buy square reserves when the rounds work just fine (and are more forgiving in a 2 out scenario -- like when an FXC misfires). Quote Share this post Link to post Share on other sites
ericber 0 #9 March 15, 2004 Good point. Thank you for your feedback.Blue Skies Eric Bernstein D-9298 [email protected] Quote Share this post Link to post Share on other sites
piisfish 135 #10 March 15, 2004 not many obstacles close to your DZ ?? lakes, forests etc ??? here in switz I think rounds are not permitted anymore with a square main.scissors beat paper, paper beat rock, rock beat wingsuit - KarlM Quote Share this post Link to post Share on other sites
chuckbrown 0 #11 March 15, 2004 Farm country near Lancaster, Pennsylvania. We won't put them out in winds in excess of 10 mph. Quote Share this post Link to post Share on other sites