Checking For Traffic

by Tom Buchanan

May 25, 2003

Ahhh, it was another perfect day for a skydive. The sky was clear and I was sitting in the right pilot seat of the Otter at 14,000 feet, ready to get out for some fresh air. As we turned on jump run I took a brief moment to watch the pilot at work. His plan was to hold runway heading for a bit, then turn the flight to about 270 and follow the grass runway along the windline. As the pilot was watching the GPS he called a very busy controller at Boston Center and gave a required warning prior to jumping. Next he reached over to tune his top radio to a frequency for New York Approach, and when the channel was clear, he repeated the warning. Then he tweaked a couple of switches and used the bottom radio to let Manifest know we were about to drop, all while he was re-tuning the first radio. As the pilot handled radio communication he was also pulling power to slow the airplane for jumprun, changing heading to overfly the grass runway, holding altitude, checking engine gauges, watching the GPS, and doing a bunch of other “pilot stuff.” Along the way he managed a quick look out the window, and when the GPS told him we had entered the “sweet spot” he quickly turned on the green light indicating we were over the spot. That was one very busy pilot...I was impressed.

As usual, when the green light went on, jumpers by the door pushed their helmets down, lifted the door, and started exiting. Several other groups and individuals followed that first group, and then, it was my turn. By the time I reached the door, 21 other jumpers had left the plane, and more than a minute had passed since the green light had been turned on. Sadly, very few of the jumpers in front of me had even taken a glance out the door, and none had bothered with a solid scan of the sky and ground. I suppose most of us have become accustomed to watching for the green light and assume that the spot will be right on. Most of the time we are correct, and the spot is absolutely, totally, truly, great.

But what happened to checking for other airplanes? Traffic conflicts happen. Other pilots occasionally wander over The Ranch, and if we are not paying attention, we could quickly be bending their metal with our bodies. Ughhh, that's a pretty unpleasant way to end an afternoon.

Most of us remember from studying for the USPA “A” license that FAA regulations make preventing traffic conflicts a responsibility shared by the pilot AND jumpers (see FAR 105.5). Pilots are busy, especially on jumprun, and they need our help...desperately. While it's pretty easy to recognize and agree that skydivers need to check for traffic before leaving the plane, most of us haven't really thought about how extensive the task is, how much airspace needs to be checked, or by whom.

So, let's take a look at how a conflict between a skydiver and an airplane happens, and then let's look at what we can do to avoid the conflict...

Problem:

Assume a jumper leaves an airplane at 14,000 feet and opens his parachute at 4,000 feet. He will have been in the air for about a minute before reaching 4,000 feet. Assuming his parachute is a large and somewhat docile canopy, he will continue descending at a standard rate of about 1,000 feet per minute and reach 2,000 feet about two minutes later, or three minutes after exiting the plane. Now, lets assume a wandering Cessna has a close call with that jumper at 2,000 feet directly over The Ranch. If the Cessna was traveling across the ground at 120 mph, how far away was it when the skydiver exited?

 Solution:

The Cessna was traveling at 120 miles per hour, or covering two miles every minute. Three minutes elapsed between exit and the encounter, so the Cessna was probably about six miles away when the now very frightened jumper departed the jump plane.

What if that Cessna was actually a larger plane traveling at 180 mph? Well, the faster plane would be covering THREE miles every minute, so it could have been as far as nine miles away. Now, what if the very frightened jumper was actually a tandem student, or just decided to open at 5,000 feet...add a minute to the parachute descent (that's three more miles of airplane travel), and the faster plane could have been as far as 12 miles away in ANY DIRECTION when the jumper exited.

Eeeeek! Suddenly it becomes apparent that before we get out of the airplane somebody needs to clear a cone of airspace as large as 24 miles in diameter and more than two miles deep. What a chore! Does anybody really believe a busy pilot can handle it alone?

Fortunately, the Twin Otters we jump from have a huge Plexiglas door in the back, and more than a dozen windows split along both sides. And we generally have more than 20 jumpers available to scan for traffic. Heck, when 20 people all help out, scanning for traffic becomes easy!

Here are a few tips to help with that scan:

· We should never rely on Air Traffic Controllers, the pilot or spotter to look for traffic. Air Traffic Control over The Ranch is split between Boston Center and New York Approach. Controllers are often as busy as the jump pilot, and may not have adequate radar coverage to detect low flying airplanes

· When you get up and start checking your gear, also start glancing out the windows closest to your position.

· Use windows on both sides of the airplane to help check for traffic in all directions.

· Keep in mind the pilot has pretty good forward visibility on the left side of the plane, but he can't see very much on the right side, or what is below or behind the plane. The spotter at the door also has a pretty good view outside the left side of the Otter, but he can't see anything on the right side. Even if the pilot and spotter are checking the left side, the right side of the plane remains pretty much unchecked.

· When looking for traffic, scan a small chunk of airspace, then move your eyes along and check another chunk. Keep visually checking outside the windows until you get out.

· Encourage your friends and fellow jumpers to help out with the traffic check.

· Remember to look down as well as off in the distance. Focus on close in airspace below the plane, but don't ignore areas that may be beyond our standard parachute glide distance. Watch for the distant traffic too.

· An airplane at about 2,000 feet and traveling toward the DZ presents the greatest danger. An airplane flying parallel to jumprun is less of a threat, as is a distant airplane just a few thousand feet below the jumprun altitude. Low flying airplanes lined up with the runway, and within about two runway lengths of the DZ, are probably landing at the airport and should be watched, but not considered threatening to jumpers under canopy.

· If you see a threatening target tell the spotter or pilot, and keep looking for other airplanes.

· If you are an instructor, have your student help out with the traffic check.

· As you move toward the door, keep using the windows on both sides to check outside.

· Make a final check for traffic before you exit, then enjoy your skydive!