Conditions Need To Be Just Right
-by Joe Duff-
Several factors must align perfectly in order for us to successfully complete a leg of the aircraft led migration.
Weather: Living at the whim of weather is not for the impatient – or anyone with a controlling personality — like me. No amount of cursing or cajoling will get you anywhere. In fact, when you plead with the powers that control the winds, your reward is the same indifferent stare you get when you try to explain to the State Trooper that the 90 mile per hour ticket he is writing, is all the fault of speedometer error.
Taking to the air in a 400 pound aircraft and cruising at 38 miles per hour is a lot like being a discarded Styrofoam cup on an interstate. So it is best to pick your conditions carefully. When you add birds to the wingtip and must fly smoothly enough to carry them on your wake, the window of opportunity is narrowed even further.
Our stopovers are approximately 60 miles apart and our birds fly at roughly 38 miles per hour. Even a smooth headwind can slow our progress over the ground past the range of our fuel tanks. Any more than three hours and we risk having to land short with the birds.
Temperature is also a consideration. The particles that make up air are packed closer together when it’s cold, so more oxygen is inhaled with each lung full. It also provides more substance to push against with each wing beat and helps cool the bird’s bodies from the exertion of flying.
Higher humidity means that a large percentage of the air is made up of water vapor. Cool that air even slightly and the water condenses into fog. Cool it more and we get frost on the wings which can quickly reduce the aerodynamics of an airfoil to the flight characteristics of a brick.
Aircraft like ours operate under visual flight rules (VFR) and the FAA imposed minimum visibility limits that include the distance you can see horizontally and the height of the clouds. With luck we can get the birds to 2 or 3 thousand feet, so the ceiling must be higher than that to fly legally. Full overcast at 10,000 feet is ideal because it blocks the sun and reduces the thermal activity that makes the air bumpy.
There are many other reasons why air can become rough or what we refer to as trashy. Wind shear can happen when the air at two different levels is moving in different directions. Sometimes turbulence will form between the layers. Close to the ground, mechanical turbulence is produced when even light winds roll over hills and forests. None of these situations is dangerous to the birds or us but they prevent us from holding the wings steady enough to allow the birds to surf on its wake.
Crew: Our crew of staff and volunteers each have jobs that must be executed and timed precisely in order for it all to work. Radios must be charged, vehicles fueled and costumes ready for when the lead pilot says go. Prior to the launch, they remove the electric fence perimeter wire and roll back the top net slightly so the gates can be opened giving the birds wide access to the departing aircraft. They must be ready to dive into the pen trailer so they don’t distract the birds, have swamp monsters at the ready to discourage those that return, if needed, and air horns to emphasise the message.
If it all goes well, they can begin dismantling the pen shortly after takeoff. It must be packed, cleaned and ready to travel in case it is needed at some halfway point. If things don’t go as planned, the ground crew must track any birds that land near the pen and have crates available to transport the dropouts. The team in the tracking van must stay in radio contact and plot a course of back roads to keep them under the aircraft and birds.
Equipment: We must also rely on equipment like battery operated GPS units and handheld radios that are not made for cold temperatures. We use MP3 players, amplified through speakers to broadcast the brood call from the air, cumbersome directional antennas and heavy tracking receivers. Among the most reliable equipment we have are the aircraft but that depends on regular and meticulous maintenance.
Timing and technique: When all the pieces fit together it is up to the lead pilot to make it happen. He must time his takeoff so the first birds out don’t get ahead of him, yet the last bird clears the pen gate. He must hold the aircraft a mile per hour above the stall, while looking over both shoulders to count the followers. He must hold the wing as steady as possible, providing clean lift for the birds just off the wingtips, and execute slow sweeping S-turns so the stragglers can cut the corners and catch up. He watches for telltale signs like the curved neck that increases drag and slows the birds down slightly because the wing is moving too slowly, or the open months of the tired birds at the back because it is going too fast.
The chase pilot must lend advice and direction while staying out of the way. When it is time to assist, he must be cautious not to attract all the birds as he tries to pick up one straggler. The best approach is from far enough back, but directly behind the lead aircraft so the other birds don’t see him as a provocation to turn back.
There are a hundred tactics and procedures that make the difference between a successful flight and one that must wait until the next flyable day.
On average it takes us twenty-three flying days to reach Florida. They are punctuated by long periods of headwinds or rain but when our break finally comes, there are a hundred other things that must also fall into place and a talented team that makes sure they all work.
http://operationmigration.org/InTheField/2013/12/23/conditions-need-to-be-just-right/
