Dealing with emergencies is a problem that the airline industry has grappled with for decades. One approach used by airlines to rapidly respond to emergencies, as well as conduct routine operating procedures, is the use of flow patterns. A flow pattern is a systematic approach that uses a specific physical pattern to help the pilot complete a procedure. When a flow pattern is followed for an emergency procedure, the checklist is used on a time-permitting basis after the completion of the pattern to ensure that no steps or items were omitted. Thus, the checklist is truly a check list and not a do list.
Using a flow pattern offers three distinct advantages. First, by following the pattern prescribed by the flow, a pilot is less likely to overlook or forget any step in the procedure. Second, a flow can be more easily and quickly learned than a written procedure. Finally, the flow can be completed very quickly since the pilot's time isn't divided between reading a checklist and performing tasks in the cockpit.
In some emergencies, particularly when there is only one pilot, there simply isn't enough time to get out the checklist and read it before the flight comes to an unscheduled end. For example, an engine failure immediately after takeoff may not leave enough time for a single pilot to read through an emergency checklist. The pilot must simply focus on flying the airplane and maintaining control until it comes to a stop. In this case, a flow pattern may be the best tool the pilot has for dealing with the situation, allowing him to respond rapidly to a critical situation.
Developing a Flow Pattern
Flow patterns used by the airlines are published as part of each carrier's standard training materials. Those of us flying aircraft that don't have published flow patterns can develop patterns that will provide us with the same benefits as our airline counterparts, but we must consider several important criteria when developing flow patterns.
First, the flow pattern should in-clude all of the items required on the checklist. Many checklists, even those found in primary training aircraft, print the first few steps of emergency procedures in bold type. This is intended to designate those items that should be committed to memory and performed prior to eliciting the help of the checklist in an emergency situation. At the very least, a flow pattern should include each of these items, though it may extend well beyond them.
Second, the flow pattern should follow a logical physical pattern in the cockpit. In some cases, the order listed in the manufacturer's checklist is significant. For such procedures as extending landing gear manually, the steps may need to be accomplished in the proper order if the procedure is to be successful. A flow pattern should take this into account. In other cases, the order is insignificant, and we can reorder the steps to create a more easily remembered physical pattern in the cockpit.
The sequence of procedures or steps completed in the flow should deal with the most important or most likely problems first. In many aircraft, the most likely cause of an engine failure is fuel mismanagement, so a properly designed flow will address this issue early in the sequence by having the pilot energize the fuel boost pump and select a different fuel tank before addressing less likely problems such as carburetor ice or a bad magneto. If fuel flow can be reestablished quickly, the pilot may be able to avoid making an emergency landing.
Finally, remember that the flow pattern doesn't take the place of the checklist. It is used to augment the checklist and assist the pilot.
Typical Emergency Flows
Let's take a typical training aircraft and see how we can use a flow to rapidly deal with an emergency. For this example we'll consider an engine failure in a Cessna 172. If the engine fails at altitude, the first order of business after assuming best glide speed, selecting a forced landing site, and turning in the proper direction is to attempt to restart the engine. The flow pattern for this procedure takes the shape of an inverted L pattern in the cockpit.
The engine restart flow pattern starts with checking the fuel selector located between the two front seats to make sure it is in one of the on positions. Next, move up to the lower, center part of the instrument panel and work across from right to left, beginning with the mixture. The mixture should be set to the full rich position and the throttle retarded to idle then slowly advanced. (Moving the throttle plate on the carburetor may dislodge ice, and readjusting the throttle after the mixture has been reset may encourage the engine to run again.) Next, the carburetor heat should be turned on. Moving to the left, check the magnetos, then verify that the primer is in and locked. This flow pattern contains all of the elements on the emergency checklist, yet the entire pattern takes only seconds to complete.
If the restart procedure is unsuccessful, the next order of business is to secure the engine for landing, and we can follow essentially the same physical pattern to complete this task. Begin by shutting off the fuel with the fuel selector. Then set the mixture to the idle-cutoff position and pull the throttle back to the idle position. Although not critical, we can turn off the carburetor heat. Moving to the left, turn off the magnetos, and then recheck that the primer is in and locked.
The same basic flow pattern can be adapted to deal with an engine fire in flight. In this emergency, the first objective is to secure the engine, so the same flow can be used. To adapt this basic flow to the engine-fire scenario, simply add a few additional steps at the end. After securing the primer, move up and turn off the master switch. Then continue up and open or close the air vent on the upper left of the windshield as necessary to minimize smoke or flames in the cockpit. Next, move across to the right and open or close the passenger air vent. Then move down and turn off the cabin air and cabin heat controls on the right side of the instrument panel. Again, this flow pattern completes all the steps listed in the emergency checklist for an engine fire in flight. Once you have finished the flow pattern, get out the checklist and verify that all of the items have been completed before executing a forced landing.
The beauty of this flow pattern is that it can be used to complete three separate emergency procedures-engine failure at altitude, securing the engine for a forced landing, and engine fire. Using the one flow pattern reduces the complexity of mastering each of these different emergency procedures.
Variations on a Theme
The procedures for engine failures and fires vary from one make and model aircraft to another, but the basic concept can be readily adapted. Let's look at another common trainer, a Piper Warrior (PA-28-161). An emergency flow for an engine restart in this aircraft is quite similar to the Cessna, but with some important differences. Rather than the inverted L pattern used in the Cessna, the pattern for the Piper starts with the fuel selector on the lower left, then makes a sweep across the panel from right to left.
Again, the most likely cause of an engine failure is fuel starvation, so the engine restart flow begins by addressing this problem. Start with the fuel selector on the sidewall beside the pilot's knee and switch to a tank with usable fuel. Now move to the right side of the lower panel and work left, turning on the fuel boost pump located in the lower center of the instrument panel. Then turn on the carb heat, enrichen the mixture, adjust the throttle, check and lock the primer, and check the magnetos.
As with the Cessna, the flow for securing the engine in the Warrior follows the same basic pattern as that for the restart-fuel selector off, fuel boost pump off, carb heat off, mixture idle-cutoff, throttle idle, primer in and locked, and magnetos off. The Warrior checklist tells us to turn off the master switch. This should be done at the last possible moment so that we can make radio calls and controllers can continue to monitor the transponder, which can provide valuable information to rescuers.
Again, the flow for an engine fire in the Warrior can follow the same basic pattern, with a few additional steps added to complete the procedures listed in the checklist. Start by turning off the fuel. Then it's fuel boost pump off, carb heat off, mixture idle-cutoff, throttle to idle, primer in and locked, and magnetos off. The continuation of the flow includes opening the vent window as necessary, then sweeping across to the right side of the panel to turn off the cabin heat and defroster.
Because of the similarities in cockpit layout and basic emergency procedures, the flows described above are easily adapted to other aircraft in the manufacturers' lines.
Going with the Flow
The key to properly performing any procedure, including a flow pattern, is constant practice. If we wait until the engine goes quiet to practice our emergency flow, it won't come as naturally as if we did it every time we fly.
So, to be better prepared for emergencies, we can utilize the same flow patterns when conducting normal operations such as runups, pretakeoff checks, and prelanding checks. Again these flows don't replace the checklists, they simply augment the process of completing the steps in the procedure. We use the checklist to verify that the job is done.
Let's take the Warrior and consider the runup (ground check) in light of using our flow pattern. Set the throttle to the desired rpm, then begin the pattern. Start by checking the fuel selector. By duplicating this item in the various flows and checklists, we are less likely to have it in the wrong position for takeoff. Next, check that the fuel boost pump is off (we want to know that the engine will run without it). Test the carburetor heat, adjust the mixture (if flying at high density altitude) and readjust the throttle for proper rpm, check the magnetos, and then check that the primer is in and locked. If we add a systematic check of all the engine gauges, annunciator lights, and instruments, then check that the air conditioner is off, our ground check is complete. We go through the checklist and verify that all the items have been completed.
By following the same pattern for the pretakeoff check and prelanding check, we find that virtually all the checklist items are covered if we just go with the flow. Some pilots add a few additional items to their flow patterns to cover even more routine items such as seat belts, flight controls, doors, and windows. In some emergency situations, including these items in our flow might help us to do a more thorough job of preparing the aircraft and our passengers for an emergency landing.
Learning to use a flow pattern is not a panacea for all aviation ills, and it doesn't take the place of other tools and resources such as checklists. But developing flow patterns and using them routinely can help to simplify training and improve our performance during both routine and emergency situations. Problems such as engine failures and fires are rare, but when the unexpected happens, it's a comfort to have the right procedures at our fingertips.
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