That statement is precisely what one does not wish to hear when test-running an aircraft following a maintenance event. The situation worsens when the aircraft is a $109 million F-35A Lightning II fighter. In January, Stars and Stripes reported that on March 15, 2023, “a hand-held flashlight left inside an F-35 engine by maintainers at Luke Air Force Base last year caused $4 million in damage.” It seems that after using a flashlight to inspect the poorly lit intake of the F-35, the maintainer failed to clear the tool before test-running the engine.

During the post accident investigation, investigators found a flashlight missing from one toolbox. The 56th Fighter Wing aircraft suffered an excess of $4 million in damage to the engine. Thankfully, no one was injured in the accident, but the engine could not be repaired locally.

This is a classic and all-too-common case of foreign object damage (FOD).

This Is FOD

FOD can be categorized as foreign object damage or debris based on the context one is referencing. FOD is a broad term that applies to just about anything. The FAA defines in Advisory Circular (AC) 150/5210-24 Airport Foreign Object Debris (FOD) Management that FOD is “any object, live or not, located in an inappropriate location in the airport environment that can injure the airport or air carrier personnel and damage aircraft.”

FAA AC No. 150/5380-5B Debris Hazards at Civil Airports addresses FOD and the ramifications of such. One key highlight states that “foreign objects on airport pavements can be readily ingested by aircraft engines, resulting in engine failure.” The FAA lists several possible FOD objects, many of which you will instantly identify as commonplace in aircraft operations. In section B of the AC, the FAA calls out “aircraft and engine fasteners (nuts, bolts, washers, safety wire, etc.); mechanics’ tools; flight line metal (nails, personnel badges, pens, pencils, etc.); stones and sand; paving materials; pieces of wood; plastic and polyethylene materials; paper products; and ice formations in operational areas.” 

FOD-Related Accidents

Just how bad is the FOD problem? One might say that the issue is an epidemic. The FAA devotes quite a bit of attention to it, and rightly so. FOD is hazardous and can negatively impact operations.

The FAA website cites the Current Airport Inspection Practices Regarding FOD (foreign object debris/damage) report, stating that FOD exists in many forms, comes from many sources, and can be found anywhere in an airport’s air operations area (AOA). The report explains how damaging FOD can be to aircraft, puncturing tires, punching holes in airframes, and nicking turbine blades or propellers. And in extreme cases, engine failure. Damage is not isolated to just aircraft or equipment. Airport employees are also susceptible to FOD-related injuries. Errant bolts or other foreign objects on the ramp could be propelled by prop wash, jet engine blasts, or helicopter rotors, turning them into mini-missiles.

• READ MORE: Breaking Down Sudden Stoppage Inspections

The report states that FOD costs the U.S. aviation industry $474 million annually. The global aviation industry’s losses are an estimated $1.26 billion annually. These totals include direct and indirect costs, such as flight delays. The FAA is asking for airports, airlines, and the general aviation community’s assistance in documenting the occurrence of FOD and submitting data to the FAA FOD database.

Despite all the awareness campaigns and actions taking place, FOD is still a significant problem that may be growing. A recent Air Force Times article states that “foreign object debris was one factor that led the number of ground accidents to nearly double from 11 in 2022 to 21 in 2023.” If anything, rates of occurrence are headed in the opposite direction. In March, USA Today reported that United Flight 1118, a Boeing 737 taking off from Houston’s George Bush Intercontinental Airport (KIAH) ingested bubble wrap into the engine, causing a midair fire. Thankfully, the incident did not result in injury.

Unfortunately, the losses are not solely in physical damage. One of the more infamous FOD-induced incidents did not fare so well. On July 25, 2000, Air France Flight 4590 departed Paris Charles de Gaulle Airport (LFPG). Prior to rotation, Concorde struck a piece of metal with its right front tire, causing it to explode and rupture the integral fuel tank. Fuel leaking from the ruptured tank ignited, creating a loss of thrust in engines 1 and 2. The aircraft lifted off momentarily but crashed into a hotel, killing all nine crew, 100 passengers, and four people on the ground. 

The Bureau Enquêtes-Accidents (BEA) report identified the FOD as a Continental Airlines DC-10 thrust reverser door wear strip that had fallen off after maintenance. 

FOD awareness and prevention deserves our attention. These examples and others illustrate that there is seemingly no end to stories of FOD causing significant property damage and loss of life, including one instance of a self-inflicted fatal FOD accident. Columbia STS-107 was lost and its space shuttle crew perished upon reentering the atmosphere while returning from a mission. According to NASA, a loose insulation panel dislodged and damaged the carbon heat shield material on the orbiter’s left wing, eventually causing the craft to succumb to the extreme heat of reentry.

FOD can come from a variety of sources, and not all incidents are the result of negligence—nature can be equally culpable. Most people are familiar with the story of Captain Chesley “Sully” Sullenberger and the “Miracle on the Hudson.” On January 15, 2009, US Airways Flight 1549 departed New York’s LaGuardia Airport (KLGA) bound for North Carolina’s Charlotte Douglas International Airport (KCLT). Approximately six minutes into the flight, the Airbus 320-214 ingested a flock of Canada geese, disabling both engines. Thankfully, Sullenburger’s skill saved the lives of all souls on board by safely ditching in the Hudson River. 

Even smaller flying objects can cause huge problems. Andrew Warwick and Blake Love recently reported to KJWN in Nashville, Tennessee, for a service call. A Challenger 350 experienced a dual-engine, nonstart condition. They arrived to find the APU inlet packed with dead cicadas. It appears that cicadas are drawn to the APU’s warmth and noise. Operators in heavy cicada areas like this are advised to run their APUs sparingly and check for FOD frequently.

FOD Prevention

To begin a FOD prevention program, start with the following:

• Identifying causes.

• Establishing an FOD awareness program.

• Establishing a maintenance program.

The AC mentioned earlier then breaks down each of the above actions with detailed guidelines to help one succeed in the fight against FOD.

• READ MORE: 5 Things You Can Do to Help Prevent Foreign Object Debris

Another resource the FAA makes available is its Foreign Object Debris Program. The website (faa.gov/airports/airport_safety/fod) reveals several tools, resources, and technical publications for managing a successful FOD program.

Marcela White, co-owner of Tavaero Jet Charter, knows FOD is serious business. When asked who was responsible for FOD risk mitigation at Tavaero, White’s simple response was—everyone.

“Pilots, mechanics, and airplane cleaners are all trained to check for any FOD damage on the airframe or in the engines,” White said. “Pilots are the last line of defense and perform their preflights with a sharp eye. Anything beyond obvious visual damage gets escalated to the maintenance department. The job is not over after the flight either. The pilots go back through everything during post-flight inspections. Crewmembers follow an extensive checklist that includes servicing the aircraft fluids, cleaning the windows and windshields to ensure no chips are found, checking oxygen levels, and checking the airframe and engine blades for FOD.”

I met John Franklin, the head of safety promotion at the European Union Aviation Safety Agency (EASA), during the T-C-Alliance online coffee chats early in 2020. I asked Franklin about his legacy of fighting FOD.

“In terms of FOD, it’s where I started my safety career, as the U.K. Defense FOD Prevention Officer, or the ‘Fodfather’ as it was called at the time,” he said with a smile.

Franklin broke down the steps EASA is taking to raise FOD awareness. 

“From our side, we are trying to promote the topic wherever the opportunity arises,” he said. 

“Every year, the EASA team participates in the annual FOD Walk at our local airport at Dusseldorf [Germany]. This provides a great opportunity to promote the importance of active FOD prevention. After the FOD Walk last year, we published an article on our Air Ops Community website [easa.europa.eu/community/topics/fod-prevention].”

Even with all EASA’s efforts, more work remains, especially with regard to getting the word out. 

“We also promote FOD, particularly when we have other promotional events and webinars on maintenance safety and airport ground handling,” Franklin said. “From our analysis, these certainly seem to be the communities that have the largest role in stopping FOD from causing a safety issue to an aircraft. Additionally, we promote the topic of clean cockpits to airlines having had some occurrences with FOD jamming flight controls or causing other problems to avionics.”

Much like a 12-step program, Franklin recognizes that awareness of the FOD problem is only the first step. One must put in parameters to stop FOD at the source.

“It’s also important to have a FOD analysis program to further identify the sources of FOD, so you can manage them at the source,” he said. “There is no point just continually cleaning away FOD without thinking where it is coming from and how to stop it.”

How the Experts Stop FOD 

FOD control begins with attention to detail, tool control, and housekeeping. There are solutions designed with this in mind. FODS LLC, located in Centennial, Colorado, provides FODS mats to prevent any material from entering the airfield by clearing the tire treads before entering the airport. They recently completed a project at Terminal 5 at Chicago O’Hare International Airport (KORD).

I asked some of the top names in the industry to help me map out strategies to deal with FOD. James Logue, the director of maintenance at Latitude 33 Aviation in Carlsbad, California, told me how his team approached the FOD issue, and provided a new perspective.

“It’s important to think about FOD proactively,” Logue said. “Think about an object and its placement in terms of how it might become FOD. I’ve seen large water bottles in a galley cabinet leak out, causing water to get under the floor and into the belly, then freezing in flight, causing a fuel valve cable to become jammed. Consider what can happen if an item breaks, spills, moves in flight, where it might migrate to, what holes it could fall in, etc.”

Despite best efforts, FOD will eventually find its way to the airport. But once you identify an object as FOD, how do you dispose of it? 

Foreign Object Debris is a company specializing in FOD receptacles. According to its website (foreignobjectdebris.com), the firm “educates the community about FOD in hopes of helping to save a loss of money and potentially lives.” If you visit the site, check out its series of FOD blogs.

Jon Byrd, executive director of aviation and TCSG state aviation program adviser for Georgia Northwestern Technical College (GNTC) in Rome, contracts with Shark-Co Manufacturing to build custom foam molds that incorporate the minimum tool list and fit them into the student’s toolbox. This could have helped out the F-35 maintainer with the missing flashlight.

Speaking of tooling, Snap-on now sells a line of FOD prevention tools. I recently read about its quarter-inch Drive Dual 80 Technology Standard Handle Foreign Object Damage Ratchet design online and how it helps to prevent FOD in sensitive work environments. The cover plate and reverse lever are permanently affixed to the ratchet head with rivets to prevent debris from small parts. The tool meets FOD and foreign material exclusion (FME) program conformance.

Duncan Aviation is the world’s largest privately owned business jet service provider. I recently met with the team and inquired about Duncan’s FOD efforts. Darwin Godemann, the team leader of the Technical Education Center, offered the following insights: FOD can be anything—a wrench, pen, eyeglasses, or even rocks and stones, and i originate in many ways—objects falling out of pockets, a wayward tool, dirt and debris, or a pilot spilling their coffee.

FOD does pose a significant threat to aircraft, one that can cost the operator tens of thousands of dollars and compromise the safety of the aircraft and its function. For example, debris can result in improper stress and wear on a wire, causing an electrical fire. Coffee spilled six months ago can drip into nooks and crannies and cause corrosion. A tool left where it shouldn’t be can shift and jam a flight control. Debris from an airfield can be sucked into an engine.

Here are some examples of Duncan Aviation’s program:

• Tool control policies require shadowboxing all toolboxes and the end-of-work inventorying of tools

• Regular FOD awareness and training with a clean-as you-go policy. If you see something, pick it up.

• Double-inspection systems. Before it puts a panel back on or closes an area of the aircraft opened for work, a second set of eyes checks it out. In addition to a QA check, this ensures there is nothing in there that doesn’t belong.

• Awareness campaigns companywide. The line department tugs have magnets under them that pick up magnetic objects as they drive on the ramp.

Here are Duncan’s best practices implemented to develop an MRO FOD program:

• General housekeeping: A clean-as-you-go mentality is the most important first step in FOD prevention.

• Effective tool control system: Account for all tooling regularly and at the end of a job. Inventory lists or tool shadowing make this task much easier.

• OK to close inspection: Inspecting all areas where maintenance was performed to ensure nothing unwanted is left behind.

FOD control is potentially everyone’s problem, so it’s also everyone’s responsibility. Safety is mission critical in aviation. Failure to control FOD could be deadly.

This feature first appeared in the July/August Issue 949 of the FLYING print edition.

The post Fight Against FOD Never Ends appeared first on FLYING Magazine.

What Are the FAA Supplemental Oxygen Requirements for Private Pilots?

You can find clear FAA oxygen requirements in 14 CFR 91.211. Here’s a quick rundown:

• Pilots must use supplemental oxygen when flying above 12,500 feet msl for more than 30 minutes.
• At cabin pressure altitudes above 14,000 feet MSL, pilots must use oxygen at all times.
• For flights above 15,000 feet MSL, all occupants (not just the pilot) must be provided with supplemental oxygen.

To make it even easier, check out this quick reference table:

It’s important to note that these are minimum requirements. As pilot Pia Bergqvist discusses, oxygen use should be considered at lower altitudes based on individual tolerance and health factors. These considerations may include physical fitness, smoking habits, and overall health, which can affect a body’s ability to cope with lower oxygen levels at altitude. 

Additionally, the FAA recommends using supplemental oxygen above 5,000 feet msl at night, as the eyes require more oxygen to maintain optimal vision in the dark. So even if you’re not legally required to use oxygen, it’s a good idea to have it handy for those night flights.

Types of Aviation Oxygen Equipment

There are several types of oxygen machines available for general aviation aircraft. Some are integrated while others are portable. Additionally, the delivery methods—and associated comfort—can vary.

Portable Oxygen Systems

Portable systems are ideal for smaller aircraft or only occasional high-altitude flights. These compact units are easily stowed and can be quickly deployed when needed. They vary in size, with some offering only a few minutes of oxygen, and others offering up to 40 hours of reliable oxygen flow. 

The technology has come a long way too. Companies like Aithre Aviation have integrated iOS apps into their systems that allow you to monitor oxygen levels and status. Most importantly, since these do not require the same certification as built-in systems, be sure to look for reliable, high-quality portable systems from reputable manufacturers.

Built-In Oxygen Systems

For frequent high-altitude flying, a built-in system may be more suitable. These permanent installations provide a continuous supply of oxygen without occupying valuable cabin space. Again, the technology has come a long way. While bottle systems are still most common, advanced systems act as oxygen generators in real-time during flight, offering an almost endless supply of oxygen.

Oxygen Masks/Cannulas

Choosing the right mask or cannula is essential for comfort and effectiveness. Options include nasal cannulas, oral-nasal masks, and quick-donning masks, each with their own advantages and limitations. While the Top Gun look is tempting, masks can be bulky and uncomfortable. Personally, I prefer a comfortable cannula for most GA situations.

Oxygen Quantity Indicators

Monitoring your oxygen supply is critical, and quantity indicators help you keep track of usage and remaining supply. Trust me, you don’t want to find yourself at altitude with an empty oxygen tank. That’s one of the biggest advantages of newer oxygen generator systems—you’ll never have an empty tank.

Using Aviation Oxygen Systems Properly

Proper use of oxygen equipment is essential for maintaining safety and avoiding hypoxia. You should read up on the dangers of hypoxia to recognize all its signs and symptoms, but in general, you should:

• Begin using oxygen as soon as you reach the altitude thresholds set by the FAA or your personal limits. Don’t wait until you feel symptoms of hypoxia, as your judgment may already be impaired.
• Adjust the flow rate according to altitude and manufacturer’s instructions, while monitoring the oxygen quantity indicator. It’s not a set-it-and-forget-it situation.
• Watch for hypoxia symptoms, such as headaches, dizziness, and confusion, and take immediate action if they occur. This often entails descending to a lower altitude and using supplemental oxygen. If you’re feeling off, don’t try to tough it out.

Another important consideration is what to do in the event of an in-flight medical emergency. Having supplemental oxygen available can be crucial for stabilizing a passenger until the aircraft can land and medical assistance is available. 

While private pilots may not have the same resources as commercial airlines, having a basic understanding of how to use your oxygen equipment to assist a passenger in distress could make a big difference.

Stay Safe and Avoid Regulatory Risks

Understanding supplemental oxygen requirements and properly using the appropriate equipment is crucial for every private pilot. 

To learn more about FAA regulations and enhance your aviation knowledge, consider enrolling in training courses offered by reputable organizations like Pilot Institute or ASA. And when choosing oxygen equipment for your aircraft, do research and select products from trusted manufacturers known for their commitment to quality and safety. 

Flying is a privilege and a responsibility. Stay informed and equipped to keep you and your passengers safe (and conscious).

FAQ

What is the oxygen requirement for an unpressurized aircraft at 15,000 feet?

At 15,000 feet msl, both pilots and passengers must use supplemental oxygen at all times in an unpressurized aircraft.

At what altitude do you need oxygen?

Pilots must start using supplemental oxygen at 12,500 feet msl if the flight exceeds 30 minutes, and continuously above 14,000 feet msl. However, some pilots may need to use oxygen at lower altitudes based on individual factors, including physical fitness, smoking habits, and overall health.

What is the normal oxygen level on a plane?

The oxygen concentration in an airplane at sea level is approximately 21 percent. As altitude increases, the air pressure decreases, reducing the effective amount of oxygen available to breathe. On most commercial airlines, the pressurized cabin will have effectively the same oxygen concentration that would be experienced at an elevation of 5,000-6,000 feet when flying at 35,000 feet. In fact, the airplane’s ability to maintain this pressurization is a large factor in determining the maximum cruising altitude.

The post Private Pilots’ Guide to Supplemental Oxygen Requirements appeared first on FLYING Magazine.

Density altitude robs an aircraft of its performance, and if the pilot isn’t aware density altitude is present, they can run out of runway and options at the same time. You shouldn’t necessarily fear density altitude, but you should respect it, and know what to expect from your airplane.

Defining Density Altitude

Density altitude (DA) is pressure altitude corrected for nonstandard temperature and humidity. If it is warmer than standard temperature (15 degrees Celsius or 59 degrees Fahrenheit at sea level), an elevated DA is possible. The warmer the air is, the less dense the air is. When you heat air, it expands. If there is high humidity, there are more water molecules between the air molecules, and we also experience less performance from the aircraft. If the aircraft is operating from a high-elevation field—for example, taking off from an airport in the mountains where there is reduced barometric air pressure—we have the three factors that create density altitude: high field elevation, high temp, and high humidity.

It is a common misconception that all three need to be present for density altitude to be an issue. Just one will do it.

The FAA provides great information on the effects of density altitude. The Pilot’s Handbook of Aeronautical Knowledge and FAA-P-8740-2 / AFS-8 (2008) HQ-08561 are good places to start. These publications warn pilots to expect an increased takeoff distance, reduced rate of climb, and an increased true airspeed on approach and landing, although the indicated airspeed will remain the same. The latter can lead to floating and running out of runway, if not corrected for, and regardless, you will experience a longer landing roll as a result.

• READ MORE: Density Altitude: Know Your Enemy

Calculating DA begins by determining pressure altitude. At the airport, pressure altitude is easy to obtain: It is the attitude displayed on the altimeter when the Kollsman window is set to 29.92 inches of mercury, or 1013.4 millibars, so head out to the airplane and use the altimeter to get the information.

If you don’t have an altimeter, use an equation to determine pressure altitude: Take the standard pressure of 29.92 and subtract the current pressure setting. Take the result and multiply it by 1,000, then add field elevation. This results in pressure altitude.

For example: Let’s say the current altimeter setting is 29.45 and the field elevation is 500 feet. Plugging these numbers into the pressure altitude formula, you get: (29.92 – 29.45 = .47), (0.47 x 1,000 = 470), and (470 + 500 = 970), so the pressure altitude is 970 feet.

Now determine the outside air temperature. You can check the outside air temperature gauge or reading on your display, or obtain it from the automated weather at the airport or an aviation weather briefing.

Using the Flight Computer

Density altitude can be determined using a mechanical E6B. For this exercise, we will say the temperature is 90 degrees Fahrenheit. You must first convert Fahrenheit to Celsius: There is a conversion scale printed on the manual E6B to find 90 degrees F = 32 degrees C. Next, find the line that has the values for air temperature in the box labeled air temperature. Locate the box labeled pressure altitude. Put the air temp over the pressure altitude.

Look at the box labeled density altitude—there is your answer. So if the pressure altitude is 1,000 feet and the temperature is 30 degrees Celsius, the pointer in the density altitude box is directed at the two-tick mark, which means the DA is approximately 2,000 feet.

If you are using an electronic E6B, follow the formula printed on the instrument, press a few buttons, and get the numbers. If using an app, drop in the numbers and see the result.

Using a Density Altitude Chart

In the absence of an app or E6B, check the POH for a density altitude chart. You can find the ambient DA by adjusting for field elevation using the numbers on the right side of the chart. Either add or subtract as necessary, then use the table to adjust for the difference between standard pressure and the altimeter setting at the airport.

If the chart is a graph, move to the side that depicts the adjusted field elevation, then find the temperature on the bottom of the graph. The point where these values intersect is the density altitude.

Over the past 10 years, online calculators have gained in popularity. One of the more user-friendly ones was created by Richard Shelquist, a pilot from Colorado. Shelquist has hundreds of hours of experience flying in the Colorado mountains, which resulted in the creation of the online density altitude calculator. Plug in the numbers and the program does the rest.

Calculate Aircraft Performance

You should be calculating aircraft performance before every flight, and it is especially important when high density altitude is present. Don’t make guesses here—get that POH or aircraft flight manual out, crunch those numbers, and be conservative. The POH/AFM was written for a fresh-from-the-factory airplane and engine, and yours probably have some hours on them. It’s OK to round up to give yourself some cushion.

For example, if you determine the required takeoff distance to clear the 50-foot obstacle at the end of the runway is 2,795 feet, round that up to 3,000 feet. Know what is off the departure end of the runway too—is it an open field or a lake or a shopping center? You don’t want to be that pilot who “thought he could make it” and came down in a parking lot.

Train for the Event

Although the CFI cannot control the weather, they can give you a demonstration of reduced aircraft performance by limiting takeoff power. Determine takeoff roll and climb out at full power—then limit the power on takeoff. For example, if you normally takeoff at 2,700 rpm at sea level, try it at 2,100 rpm.

The runway needs to be long enough for the aircraft’s takeoff roll to result in a safe liftoff and climbout. The CFI calls the learner’s attention to the lengthy takeoff roll, cautioning against the urge to yank the airplane into the air as this can result in it settling back on the runway or a stall. Note the sluggish liftoff and climb. When the aircraft has cleared a specific altitude, apply full power to really notice the difference in performance. There should be an emphasis on the procedures: identifying an abort point on the runway, the proper liftoff point and climbout speed, and aircraft configuration.

If you have access to an advanced aviation training device (AATD), it is easy to have the aircraft take off from a mountain airport on a hot day. I use Ranger Creek Airport ( 21W) in Greenwater, Washington. The asphalt runway measures 2,975 feet and the field elevation is 2,650 feet msl. Crank up the temperature to 90 degrees and you have a teachable moment. The key points to include are configuring the aircraft for takeoff—including leaning the mixture per the POH—the use of flaps, and determining takeoff roll and climbout. Treat the event as if it is real world, verifying airspeed before attempting to climb out so the aircraft does not stall or settle back on the runway.

A Cautionary Tale

As the day gets warmer, density altitude increases, but this rise is not linear—and it can happen so quickly it takes you by surprise.

A 400-hour private pilot wanted to fly from his home field of Pierce County Thun Field (KPLU) to Packwood Airport (55S) in Washington. The pilot was taking part in the Airport Passport program and wanted to get the Packwood stamp in his book. It is a short flight—approximately 39 nm—but into rising terrain as Packwood, field elevation of 1,057 feet, is located just south of Mount Rainier. The runway measures 2,356 by 38 feet. The field elevation of KPLU is 538 feet msl, and the runway measures 3,651 by 60 feet.

It was a day in early August, and the pilot—knowing density altitude would be an issue by afternoon—opted to fly in the morning. Although he was a fully certificated, current, and proficient pilot, he asked a CFI from the local flight school to accompany him, as he had very little experience with mountain flying. When they took off, the DA, as reported by KPLU’s automated weather, was 1,900 feet, a value easily handled by his Cessna 172.

They made it to Packwood but ran into trouble on the departure. According to the pilot, the aircraft “just didn’t have the juice” for a safe takeoff. After multiple attempts, they decided the best course was to leave the airplane and come back early in the morning when density altitude was at its lowest. The mother of the CFI drove out to get them. I found out about the situation several hours later—both the pilot and CFI explained the situation by saying they did not think the density altitude would get so high so quickly. Fortunately, they made the right choice to leave the airplane behind.

This column first appeared in the August 2023/Issue 940 of FLYING’s print edition.

The post Be Prepared to Deal with the High DA Blues appeared first on FLYING Magazine.

If you fly aerobatic category aircraft, spins come as naturally as turns. So why does the fear of them arise? Simply put, it’s a lack of knowledge and understanding. Your airplane will typically not spin on its own. The pilot has to put in the proper control inputs to induce a spin in most cases–or allow it to enter a remote corner of the flight envelope. 

Your airplane may stall on its own, but many light aircraft have been designed to either resist a stall entry or begin to recover on their own. Therefore, the airplane typically is doing exactly what it was designed to do–which for most light single-engine airplanes is flying straight and level, not stalling or spinning.

Airplane’s Airspeed

Remember, your airplane needs a minimum amount of airspeed to generate the lift necessary to fly. Once flying, the airplane has a wide range of airspeeds at which it is safe to operate. At the lower end of the spectrum is the stall speed in various configurations, below which, the wing loses lift and typically causes the aircraft to descend. At the upper end is the never-exceed speed, or maximum design airspeed  (V_NE) If this speed is exceeded, the airplane may suffer damage or structural failure because you have sped past its limits. 

This is one reason why you learn about V_NE (never-exceed speed or red line) and V_NO (maximum speed for normal operations/maximum structural cruising speed or the bottom of the yellow arc), as well as maneuvering speed, V_A, when you are learning to fly. You can find out more about maneuvering speed here.[https://www.flyingmag.com/myth-maneuvering-speed/]

In general, you will perform most flight maneuvers at V_A, maneuvering speed, or below, and this speed varies with the aircraft’s weight and configuration. You will also stay below V_NO unless you are in smooth air, in order to reduce the risk of inducing structural damage on the airframe if you encounter turbulence or wind shear. The maximum speed, V_NE, is the top limit never to exceed.

Angle of Attack

Let’s first review the Bernoulli Principle, named after the Swiss mathematician and physicist Daniel Bernoulli. He realized that an object moving through a fluid, be it water or air, exhibits certain predictable results. 

Let’s look at an airplane wing. The “front” edge is called the leading edge. The “back” edge is called the trailing edge. A line drawn from the leading edge to the trailing edge is called the chord line. A line drawn perpendicular from the chord line to the upper and lower surface of the wing is the camber. 

A typical wing on a single-engine piston airplane has a greater camber on the top side of the wing than the bottom side of the wing. This means the wing generally has more of a curve on the top than the bottom. Airplane wings incorporate a variety of airfoil designs depending on their primary use.

According to Bernoulli, as a given airfoil moves through the air, the air is forced to travel around the wing. Because of the greater camber, or curve, on the upper section of a typical wing, the air has a farther distance to travel over the top of the wing, than it does under the bottom of the wing. 

As a result of the greater distance traveled, the air flows faster over the top of the wing, and as a consequence the top of the wing creates a slightly lower pressure area than does the bottom of the wing, creating a lifting force toward the lower pressure area.

This principle, combined with Sir Isaac Newton’s Second Law of Motion, “for every action, there is an equal and opposite reaction,” created the basic ingredients for flight.  Well, there are a few more important considerations to create an airplane, but the airfoil is primary among them. 

Now, as our intrepid airfoil moves forward through the air, it experiences a “relative wind” that is equal in velocity but opposite in direction to the movement of the wing. It also creates drag as a by-product of generating lift. Remember Isaac Newton? Pilots know this as induced drag, which among other things reduces our wing’s efficiency. If we were to draw the chord line of our wing and draw a line that represents the relative wind, the angle formed by those two lines is called the angle of attack. As the angle of attack increases, initially so does both lift and drag, with lift increasing faster than drag. At a point, airflow is disrupted over the wing, and the production of lift lowers dramatically. This point is called the critical angle of attack. Exceeding the critical angle of attack will result in the wing stalling, which will result in the nose pitching down—meaning it naturally wants to go to a lower angle of attack in most airplane designs.  

Stalls

As the pilot you have control over the angle of attack, but not the critical angle of attack. This is an aerodynamic limit engineered into the airplane. The critical angle of attack is the point at which the airplane will stall. The airplane is now generating drag faster than lift, and as such its aerodynamic behavior changes, and so does how the pilot controls the airplane.  Pilots are trained to recognize when an aircraft is getting close to the critical angle of attack, and to promptly recover by adding forward elevator pressure, or relaxing the back elevator pressure to decrease, or lower, the angle of attack below critical. There are many aerodynamic clues that a pilot is trained to use to correct a stall situation.

Controlling the Stall

During stalled conditions, the ailerons may not work the way you expect. The aileron deflected towards the ground will generate more drag than the aileron deflected toward the sky–and aerodynamically, your ailerons in a stall may not respond in the same way. You will need to follow the specific recommendations made by your instructor and the airplane’s manufacturer when experiencing a stall–but generally, you should keep the ailerons neutral.

Instead, recovery will focus on using the rudder, in most cases. Your rudder controls “yaw,” which is a side-to-side movement of the nose of the airplane about the vertical axis of the airplane. During a stall, it’s the correct control input for maintaining control of your airplane. Like other flight control inputs, you will apply rudder in the direction you wish to move the nose, and then return the pedal to neutral. If you are stalled and hold rudder input, you are may cause the airplane to enter a spin. 

Stall Recovery 

Stall recovery is simple. You recover by adding forward elevator pressure, or at least relaxing the back elevator pressure to decrease, or lower, the angle of attack below the critical point. There’s no need to panic—your airplane will respond to all of your control inputs. Just gently release the elevator back pressure and you will recover from the stall.  

Spins

While it is true that your airplane has to be stalled before it will spin, it is not the stall that causes the spin, it is excessive yaw while in the stall that will cause the autorotation we call a spin. Stall your airplane, don’t move your feet, and make full aileron deflections and see what might happen. 

Spin Recovery

Not all airplanes can be so easily coaxed into a stall or spin, but if you enter one, recovery is usually straightforward. 

You can remember the general steps using the following mnemonic, courtesy of Rich Stowell:

P – Power to idle

A – Ailerons to neutral

R – Rudder FULL opposite to the direction of spin rotation

E – Elevator forward to transition out of stalled flight

When the spin is over:

R – Rudder to neutral

E – Elevator input as required back to level flight.

Learn more about flying today!

You should not be afraid of stalls and spins. Your airplane is actually doing exactly what it was designed to do–and as a pilot, you will be taught the basics of stall recovery in your initial lessons.

If you want to explore spins in detail, find a good aerobatic flight instructor with experience to “show you the ropes” and don’t be afraid of flying in the stalled flight region. You just may become addicted to stalls and spins. To learn more about flight techniques, subscribe to FLYING magazine.

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