ask flying Archives - FLYING Magazine https://cms.flyingmag.com/tag/ask-flying/ The world's most widely read aviation magazine Wed, 31 Jul 2024 14:53:40 +0000 en-US hourly 1 https://wordpress.org/?v=6.4.4 How Do You Obtain a Student Pilot Certificate After a Break in Training? https://www.flyingmag.com/ask-flying/how-do-you-obtain-a-student-pilot-certificate-after-a-break-in-training/ Wed, 31 Jul 2024 14:53:37 +0000 https://www.flyingmag.com/?p=212425&preview=1 Just sit down with the lapsed learner and create a new application online.

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Question: I am a newly certificated flight instructor, and a lapsed student pilot has asked me to finish his training. He has one of the old paper student pilot certificates dated 2002. How do I fill out the integrated airman certification and rating application (IACRA) without messing things up if he already has a student certificate on file?

Answer: You’re in luck. The paper student pilot certificate was issued by the aviation medical examiner (AME) and not done through IACRA as we know it, so it is doubtful the learner already has an IACRA account.

All you have to do is sit down with the learner and create a new application. Simply follow the prompts and fill out the application. In a few weeks he will get a plastic student pilot certificate in the mail.

Also, don’t forget to also verify the learner’s citizenship and give him a TSA endorsement, which have become requirements since 2002.

Do you have a question about aviation that’s been bugging you? Ask us anything you’ve ever wanted to know about aviation. Our experts in general aviation, flight training, aircraft, avionics, and more may attempt to answer your question in a future article.

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What to Do When You Lose Your Logbook https://www.flyingmag.com/ask-flying/what-to-do-when-you-lose-your-logbook/ Wed, 17 Jul 2024 16:47:51 +0000 /?p=211569 If you can't put your hands on your logbook, here's what the FAA will accept as proof of hours.

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Question: I have more than 8,900 hours logged as PIC and hold several instructor ratings. The trouble is I can’t find my older logbooks. I moved and I think they are in a storage unit thousands of miles away. Will the FAA accept an 8710 form as proof of hours?

Answer: According to an FAA spokesperson:  “Generally speaking, the FAA will accept [a pilot’s] last airman certificate application (Form 8710-1) or what they reported on their last medical application (Form 8500-8).” You should have access to at least one of those documents.

Pro tip: Moving forward, you may want to invest in an electronic logbook and save the information to the cloud, or at least record a digital image of each page of the paper logbook when you fill it up. If you rent aircraft, sometimes you can re-create your experience by cross-referencing your receipts. 

Do you have a question about aviation that’s been bugging you? Ask us anything you’ve ever wanted to know about aviation. Our experts in general aviation, flight training, aircraft, avionics, and more may attempt to answer your question in a future article.

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What Is the Rudder Used for in Flying? https://www.flyingmag.com/ask-flying/what-is-the-rudder-used-for-in-flying/ Wed, 10 Jul 2024 16:41:41 +0000 /?p=211098 Those pedals are there for a reason. Here's why.

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Question: I fly in Microsoft Flight Simulator 2020. I was wondering, what do you use the rudder for in flight?

Answer: Rudder controls the side-to-side motion of the nose of the airplane—the technical term for this is yaw.

To make the airplane turn (bank), the pilot moves the yoke or stick in the direction they want to turn. This activates the ailerons, which are the outboard, moveable panels on the wings.

The downward-deflected panel is on the outside of the turn, and as the downward deflection increases the surface area of the wing, it generates more lift. The aircraft nose yaws toward the side with the wing generating more lift. From the pilot’s perspective, that yaw is in the opposite direction of the turn. As this turn is opposite to the direction of the turn the pilot wants, the technical term for this is adverse yaw. 

In the airplane, banking without using the rudders feels a little bit like someone pulling you sideways by the seat of your pants. It is poor airmanship as it results in an uncoordinated turn.

In an aircraft with a turn coordinator or slip skid indicator (the instrument that has a tube and ball in it that acts in response to lateral motion), note that if the airplane is banked only with aileron, the ball will be to the outside of the turn. To correct this, the pilot steps on the rudder on the same side the ball is deflecting to. This corrects the adverse yaw.  “Step on the ball” is the phrase you often hear. When flying an aircraft with a glass panel that has a triangle with a lateral moving base, the phrase “step on the line” is used.

The rudder controls the adverse yaw, and when correctly applied results in a coordinated (smoother) turn.

For more information refer to the Pilot’s Handbook of Aeronautical Knowledge (available on the FAA website or at brick-and-mortar stores) in Chapter 6, Flight Controls.

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Is Sferics Equipment Still Needed in the Cockpit? https://www.flyingmag.com/ask-flying/is-sferics-equipment-still-needed-in-the-cockpit/ Wed, 03 Jul 2024 17:47:23 +0000 /?p=210678 It depends on the mission and how much money you’re willing to spend.

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Question: Now that ground-based lightning has made its way into our cockpits, is there still a need for a sferics device such as a Stormscope? 

Answer: It depends on your mission and how many Ben Franklins you have to spare. Your sferics (short for radio atmospherics) equipment may represent the only real-time weather you’ll ever see in your cockpit.

Sure, panel-mounted and portable weather systems deliver their product in a timely fashion, but it will never be as immediate as your sferics device. Once you understand how to interpret your real-time lightning guidance, it can become a valuable asset in your in-flight aviation toolkit. 

Choices in the Cockpit

You have two options if you want lightning data in the cockpit: You can choose from ground-based lightning sensors or onboard lightning detection from a sferics device such as a Stormscope.

A Stormscope provides real-time data but does require some basic interpretation. Ground-based lightning, on the other hand, is a bit delayed and is only available through a data link broadcast at this time. Ground-based lightning is normally coupled with other weather guidance, such as ground-based weather radar (NEXRAD), surface observations, pilot weather reports, and other forecasts.   

Ground-Based Lightning

The ground-based lightning that’s now available through the Flight Information System-Broadcast (FIS-B) comes from the National Lightning Detection Network (NLDN). This network of lightning detectors has a margin of error of 150 meters for locating a cloud-to-ground strike. The ground-based lightning sensors instantly detect the electromagnetic signals given off when lightning strikes the earth’s surface.    

With 150-meter accuracy, I’d choose ground-based lightning any day. Don’t get too excited, though. Ground-based lightning is expensive (the data is owned by private companies like Vaisala), and you’ll not likely see a high-resolution product in your cockpit anytime soon.

SiriusXM satellite weather pulls from a different lightning detection network and includes both cloud-to-ground and intracloud lightning. It produces a 0.5 nm horizontal resolution lightning product. This means that you will see a lightning bolt or other symbol arranged on your display in a 0.5 nm grid.

Even if 50 strikes were detected minutes apart near a grid point, only one symbol will be displayed for that grid point. Same is true for the FIS-B lightning.

Lightning is watered down into a grid with the SiriusXM and FIS-B broadcasts. [Courtesy: Scott Dennstaedt]

Stormscope Advantages

A Stormscope must be viewed as a gross vectoring aid. You cannot expect to use it like onboard radar.

Nevertheless, it does alert you to thunderstorm activity and will provide you with the ability to see the truly ugly parts of a thunderstorm.  Where there’s lightning, you can also guarantee moderate or greater turbulence.   

No lightning detection equipment shows every strike, but the Stormscope will show most cloud-to-ground and intracloud strikes. This allows you to see the intensity and concentration of the strikes within a cell or line of cells with a refresh rate of two seconds. It also lets you see intracloud electrical activity that may be present in towering cumulus clouds even when no rain may be falling.

Even if no cloud-to-ground strikes are present, intracloud strikes may be present. The Stormscope can detect any strike that has some vertical component (most strikes do). This is important since there are typically more intracloud strikes than cloud-to-ground strikes.

To emphasize this point, most of the storms in the Central Plains have 10 times more intracloud strikes than cloud-to-ground strikes. Moreover, during the initial development of a thunderstorm, and in some severe storms, intracloud lightning may dominate the spectrum. 

Also keep in mind that a sferics device does not suffer from attenuation like onboard radar. That is, it can “see” the storm behind the storm to paint cells in the distance out to 200 nm, but it does not see precipitation or clouds.     

Stormscope Disadvantages

It doesn’t take a full-fledged storm, complete with lightning, to get your attention.

Intense precipitation alone is a good indicator of a strong updraft (or downdraft) and the potential for moderate to severe turbulence in the cloud. Consequently, the Stormscope does not tell you anything about the presence or intensity of precipitation or the absence of turbulence.

Never use the Stormscope as a tactical device to penetrate a line of thunderstorm cells. Visible gaps in the cells depicted on the Stormscope may fill in rapidly. Fly high and always stay visual and you will normally stay out of any serious turbulence.        

A Stormscope display is often difficult to interpret by a novice. Radial spread, splattering, buried cables, and seemingly random “clear air” strikes can create a challenge for the pilot. It may take a couple years of experience to be completely comfortable interpreting the Stormscope display. Often what you see out of your window will confirm what you see on your display.    

Radial Spread

As the name suggests, the biggest Stormscope error is the distance calculation along the radial from the aircraft.

The placement of the strike azimuthally is pretty accurate. However, how far to place the strike from the aircraft along the detected radial is a bit more complicated and prone to error.

Lightning strikes are not all made equally. When the sferics devices were invented back in the mid-1970s, they measured the distance of the cloud-to-ground strike based on the strength of the signal (amperage) generated by the strike. An average strike signature of 19,000 amperes is used to determine the approximate distance of the strike.

Statistically, 98 percent of the return strokes have a peak current between 7,000 and 28,000 amperes. That creates the potential for error in the distance calculation. This error is a useful approximation, however, in that strokes of stronger intensity appear closer and strokes of weaker intensity appear farther away. 

In strike mode, you can see the lightning symbols protrude radially toward the airplane. [Courtesy: Scott Dennstaedt]
In cell mode the Stormscope attempts to cluster strikes around the location of the cell. [Courtesy: Scott Dennstaedt]

In strike mode on the Stormscope, strikes are displayed based on a specific strike signature, whereas cell mode on the newer Stormscope models uses a clustering algorithm that attempts to organize these strikes around a single location or cell.

Cell mode will even remove strikes that are not part of a mature cell. Most thunderstorm outbreaks are a result of a line of storms. Cell mode provides a more accurate representation to the extent of the line of thunderstorms.

Radial spread is not necessarily always a bad thing. You can use it to your advantage to distinguish between false or clear air strikes and a real thunderstorm. Most of the strikes of a real storm will be of the typical strike signature and be placed appropriately.

As mentioned above, stronger than average strikes will be painted closer to the airplane. Looking at this in strike mode, a line of these stronger strikes will protrude toward the aircraft.  The result is a stingray-looking appearance to the strikes.    

You can confirm this by clearing the display.  The same stingray pattern should reappear with the tail protruding once again toward the airplane.

Clear Frequently

Clearing the Stormscope display frequently is a must.  How quickly the display “snaps back” will provide you with an indication of the intensity of the storm or line of storms.

You should be sure to give these storms an extra-wide berth.  Clearing the Stormscope in “clear air” will also remove any false strikes that may be displayed allowing you to focus on real cells that may be building in the distance.

One of my before takeoff checklist items now is to clear the Stormscope display. Failing to do so might leave you a bit perplexed after takeoff if you see this on the Stormscope display. I happened to taxi over a buried cable on the way to the runway. [Courtesy: Scott Dennstaedt]

Aging

Both ground-based and onboard lightning use a specific symbol to indicate the age of the data.

For Stormscope data shown on the Garmin 430/530, a lightning symbol is displayed for the most recent strikes (first six seconds the symbol is bolded). The symbol changes to a large plus  sign after one minute followed by a small plus  sign for strikes that are at least two minutes old. Finally, it is removed from the display after the strike is three minutes old.

Cells with lots of recent strikes will often contain the most severe updrafts and may not have much of a ground-based radar signature. Cells with lots of older strikes signify steady-state rainfall reaching the surface that may include significant downdrafts. 

Flight Strategy

A nice feature of a Stormscope is that you can quickly assess the convective picture out to 200 nm while still safely on the ground. Same is true for lightning received from the SiriusXM datalink broadcast.

However, for those with lightning from FIS-B, you won’t receive a broadcast until you are well above traffic pattern altitude unless your departure airport has an ADS-B tower on the field.  

As soon as your Stormscope is turned on, within a few minutes you’ll get a pretty good picture of the challenging weather ahead. If you are flying IFR, you may want to negotiate your clearance or initial headings with ATC to steer clear of the areas you are painting on your display. I’ve canceled or delayed a few flights based strictly on the initial Stormscope picture while I was still on the ramp. 

Another goal is to fly as high as allowable. You will benefit from being able to get above the haze layer, and the higher altitude will allow you to see the larger buildups and towering cumulus from a greater distance.

If you are flying IFR and you are continually asking for more than 30 degrees of heading change to get around small cells or significant buildups, then you should call it quits. You are too close, or you are making decisions too late.

Visual or not, the goal is to keep the strikes (in cell mode) out of the 25-mile-range ring on your Stormscope. If one or two strikes pop into this area, don’t worry. Just keep most of the strikes outside of this 25-mile ring.      

Don’t discount the value of a sferics device.  Add one of the data link cockpit weather solutions as a compliment, and you will have a great set of tools to steer clear of convective weather all year long.

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How Do I File a Pilot Weather Report Online? https://www.flyingmag.com/pilot-proficiency/how-do-i-file-a-pilot-weather-report-online/ Wed, 12 Jun 2024 13:05:40 +0000 /?p=209413 One of the most cumbersome tasks in GA flight is the PIREP.

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Question: How do I file a pilot weather report online?

Answer: In general aviation, one of the most cumbersome things to do while in flight is to file a pilot weather report, more commonly known as a PIREP. This has created the unfortunate situation that on any given day 98 percent of the PIREPs in the system are typically describing weather conditions at or above 18,000 feet.

It wasn’t all that long ago that the Enroute Flight Advisory Service (EFAS) was available primarily for pilots to receive weather updates while they were flying to their destination. More importantly, EFAS was the main outlet to file a PIREP such that it was guaranteed to be input into the system and become available for other pilots to see. This service was also called Flight Watch.

Given that EFAS was organized by Air Route Traffic Control Centers (ARTCC), you simply put 122.0 MHz into your radio, keyed the mic, and referenced them by a particular center’s airspace you were located within. For example, if you were in the Jacksonville Center’s airspace in Florida, your initial call might have been, “Jacksonville Flight Watch, Skyhawk One Two Three Whiskey X-ray, 30 miles southwest of the Brunswick V-O-R at five thousand five hundred.” Then as long as you were more than 5,000 feet above the ground, someone from Flight Watch came on the frequency, and you engaged in a two-way conversation to file your PIREP.

However, EFAS was terminated on October 1, 2015. This now leaves the arduous task of finding the right Flight Service Station (FSS) frequency, making contact, and hoping someone on the other end responds to your call. The frequency you use to transmit and receive is dependent on your location. Pull out your VFR sectional (paper or electronic version), find the nearest VOR to your location, and look for the frequency located on the top of the VOR information box.

Of course, the correct frequency to use may also be available through your avionics or one of the many heavyweight electronic flight bag apps.

This is the frequency you will use to transmit and receive. Below the box is the name of the particular FSS to use in your initial call. For example, if you are near the Brunswick VORTAC in Georgia, your initial call may be, “Macon Radio, Skyhawk One Two Three Whiskey X-ray, transmitting and receiving on 122.2, over.” This is the easy case.

If there’s an “R” shown at the end of the frequency (e.g., 122.1R), then that means FSS will receive on this frequency and you will transmit on this frequency. And you’ll need to be sure you listen for its response over the VOR frequency. Make sure your volume is turned up and not muted on your VOR radio.


This column first appeared in the May 2024/Issue 948 of FLYING’s print edition.

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Can Student Pilots Perform Preventative Maintenance on Aircraft? https://www.flyingmag.com/pilot-proficiency/can-student-pilots-perform-preventative-maintenance-on-aircraft/ Wed, 29 May 2024 19:03:54 +0000 /?p=208533 FAA regulations allow someone who does not hold a mechanic or repairman certificate to perform certain preventive maintenance.

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Question: I am confused about the rules regarding preventative maintenance that pilots can perform on airplanes. I am a student pilot. In ground school we learned about 14 CFR 43 Appendix A, Part C that lists preventative maintenance that can be done legally, but the chief CFI of the flight school says under no circumstances can a student pilot touch an airplane with a tool. Is there a regulation I am missing?

Answer: According to the FAA, aircraft used by Part 141 pilot schools must be maintained under the same requirements as aircraft operated under Part 91. FAA regulations allow someone who does not hold a mechanic or repairman certificate to perform certain preventive maintenance under Part 91.

The regulation you are referring to applies to a certificated pilot. That is a private pilot, sport pilot, or higher—a student pilot is not a certificated pilot, therefore the student pilot doing preventative maintenance on an aircraft would not be permitted. In addition, 14 CFR Part 43 notes that maintenance can only be done when the aircraft is not used under 14 CFR Part 121, 127, 129, or 135. If the flight school also uses the airplanes for charter operations (Part 135), that’s another reason you cannot touch them.

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Is There an Official Weather Briefing? https://www.flyingmag.com/pilot-proficiency/is-there-an-official-weather-briefing/ Wed, 22 May 2024 18:37:13 +0000 /?p=208105 Some CFIs and flight schools advocate using a subscription-based service for weather briefings. Here's why.

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Question: Is there such a thing as an official source for a weather briefing?

I have been using 1800WXBRIEF.com and Aviation Weather Center for years since they don’t require a paid subscription. But according to the CFIs at the school I just started flying with, these are not considered legal weather briefings. 

Answer: The question asked begs another one: Legal to whom? 

FAA regulations, notably FAR 91.103, require pilots to obtain weather reports and forecasts. However, according to an FAA spokesperson, “the FAA does not prefer one weather source over another, nor do we define a ‘legal weather briefing.’ It is up to the pilot in command (PIC) to use a weather source that best suits their needs and allows them to meet the preflight planning requirements.

That being said, there are some CFIs and flight schools that advocate paid subscriptions, such as ForeFlight, and free discreet login services, such as 1800WXBRIEF, because in addition to providing information, they also allow the pilot to file a flight plan. They also require an account, which means it’s easier to prove the pilot obtained a weather briefing prior to the flight because there will be a record of the login.

The latter is often one of the first things the National Transportation Safety Board checks when it investigates an accident or incident.

At the very least, a pilot should check TAFs, METARs, winds aloft, and NOTAMs prior to a flight. It is distressing how many pilots and pilots in training believe that listening to the ATIS/ASOS/AWOS at the airport or along their route constitutes a weather briefing. They don’t. 

Nor does looking out the window at the FBO. Any more than “pretty good” is a PIREP. 

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How Do You Know When to Descend? https://www.flyingmag.com/how-do-you-know-when-to-descend/ Wed, 08 May 2024 18:34:43 +0000 https://www.flyingmag.com/?p=202469 At a strange airport, the landmarks a pilot becomes accustomed to at home are missing.

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Question: How do you know when to start your descent? At my home airport I plan my descents by using landmarks—be at this altitude over the water tower because that will put me at pattern altitude, etc. How am I supposed to do that when I go to an airport that I am unfamiliar with?

Answer: You have just described knowing the top of descent—that is, knowing how much time and distance it will take you to reach the predetermined altitude, such as the pattern.

There are two basic means to do this.

First, determine how much altitude you need to lose. Let’s say you are at 3,500 feet and the traffic pattern altitude (TPA) is 1,000 feet. 3,500 – 1,000 = 2,500, so you need to lose 2,500. If you are descending at 500 feet per minute, 2,500/5 = 5 minutes to get to TPA.

Next, determine distance for descent. Take your current altitude: 3,500 feet. Subtract the traffic pattern altitude of 1,000 feet = 2,500. Multiply the altitude to lose by 3, so 3 x 2,500 = 7,500.  Divide this by 1,000 and get the approximately distance to the airport  = 7,500/1,000 = 7.5 miles.

Looking at the VFR sectional, put a mark that is at the distance from the airport, especially if it is over a landmark like a lake, fairgrounds, etc., or if using GPS, refer to that. You can adjust your rate of descent if you are coming down too quickly when you have the distance in mind. 

Make a point to practice this. You don’t want to be that pilot who flies pattern altitude (or accidentally lower) miles from the airport, nor do you want to be the pilot who forgets to start a descent and dives into the pattern. But don’t worry. We have not had an aircraft stay stuck up there yet.

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What Is an Outflow Boundary Shown on a Surface Analysis Chart? https://www.flyingmag.com/what-is-an-outflow-boundary-shown-on-a-surface-analysis-chart/ Wed, 01 May 2024 16:01:36 +0000 https://www.flyingmag.com/?p=201697 Here's a step-by-step guide to deciphering surface analysis charts—particularly ‘gust fronts.’

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Question: What is an outflow boundary shown on a surface analysis chart?  

Answer: When looking at the surface analysis chart issued every three hours by meteorologists at the Weather Prediction Center (WPC), you may have seen a tan dashed line with a label “OUTFLOW BNDRY” nearby. This is what meteorologists call a convective outflow boundary.

You may view North American surface analysis here.

Convective outflow boundaries emanating away from thunderstorms are generated as cold, dense air descends in downdrafts then moves outward away from the convection to produce a mesoscale cold front also known as a “gust front.” 

Some gust fronts can be completely harmless or may be a precursor for an encounter with severe turbulence and dangerous low-level convective wind shear. The direction of movement of the gust front isn’t always coincident with the general motion of the thunderstorms. If the gust front is moving in advance of the convection, it should be strictly avoided. The pilot’s best defense is to recognize and characterize the gust front using METARs, ground-based radar, and visible satellite imagery.

As a thunderstorm evolves, it will bring in warm, moist air to feed the intense updraft (yellow), providing fuel for it to intensify. Once the precipitation core is too heavy to be supported by the updraft, cold, dense air will flow down through the storm (red), striking the ground and moving outward away from the convection that generated it. [Courtesy: Scott Dennstaedt]

According to research meteorologist and thunderstorm expert Charles Doswell, “cold, stable air is the ‘exhaust’ of deep, moist convection descending in downdrafts and then spreading outward like pancake batter poured on a griddle.” 

As a pulse-type thunderstorm reaches a point where its updraft can no longer support the load of precipitation that has accumulated inside, the precipitation load collapses down through the original updraft area. Evaporation of some of the rain cools the downdraft, making it even more dense compared to the surrounding air. When the downdraft reaches the ground, it is deflected laterally and spreads out almost uniformly in all directions, producing a gust front.

Gust fronts are normally seen moving away from weakening thunderstorm cores. Once a gust front forms and moves away from the convection, the boundary may be detected on the NWS WSR-88D NEXRAD Doppler radar as a bow-shaped line of low reflectivity returns usually 20 dBZ or less. Outflow boundaries are low-level events and do not necessarily produce precipitation. Instead, the radar is detecting the density discontinuity of the boundary itself along with any dust, insects, and other debris that may be carried along with the strong winds within the outflow. The gust front in southwest Missouri shows up very well on the NWS radar image out of Springfield as shown below.

Crescent-shaped convective outflow boundary as detected on NEXRAD Doppler weather radar. [Courtesy: University Corporation for Atmospheric Research]

An important observation is to note the motion of the gust front relative to the motion of the convection. In this particular case, the boundary is steadily moving south while the thunderstorm cells that produced the gust front are moving to the east. This kind of outflow boundary is usually benign, especially as it gains distance from the source convection. On the other hand, a gust front that is moving in the same general direction in advance of the convection is of the most concern. These gust fronts often contain severe or extreme turbulence, strong and gusty straight-line winds, and low-level convective wind shear.

As mentioned previously, gust fronts are strictly low-level events. As such, even the lowest elevation angle of the radar may overshoot the boundary if it is not close to the radar site. 

Shown below at 22Z, the NWS WSR-88D NEXRAD Doppler radar out of Greenville-Spartanburg, South Carolina, is the closest radar site and clearly “sees” the gust front (right image). However, the NEXRAD Doppler radar out of Columbia, South Carolina (left image), is farther away and misses the gust front completely. As the gust front moves away from the radar site, it may appear to dissipate, when in fact, the lowest elevation beam of the radar is simply overshooting the boundary. As a result, it is important to examine the NEXRAD radar mosaic image before looking at the individual radar sites.

Outflow boundaries are a low-level phenomenon. The lowest elevation angle beam from the NEXRAD radar located at the Columbia, South Carolina (CAE), weather forecast office (left) is overshooting the outflow boundary that is detected by the Greenville-Spartanburg NEXRAD radar site (right) located closer to the outflow boundary. [Courtesy: Scott Dennstaedt]

Not all gust fronts are easy to distinguish on visible satellite imagery; the gust front could be embedded in other dense clouds, or a high cirrus deck may obscure it. It is also possible that the boundary may not have enough lift or moisture to produce clouds. In many cases, however, it will clearly stand out on the visible satellite image. When the gust front contains enough moisture, as it was in this situation, cumuliform clouds may form along the boundary and move outward as can be seen in this visible image below centered on Charlotte, North Carolina. This is very common in the Southeast and coastal regions along the Gulf of Mexico given the higher moisture content. 

Convective outflow boundary emanating away from convection and captured on visible satellite imagery. [Courtesy: University Corporation for Atmospheric Research]

As this particular gust front passed through my neighborhood located south of Charlotte, strong, gusty northerly winds persisted for about 10 minutes. As is common, the main core of the precipitation didn’t start to fall for another 10 minutes. When a gust front such as this appears on satellite or radar, it is important to monitor the METARs and ASOS or AWOS closely for the occurrence of high winds. Several airports in the vicinity reported wind gusts peaking at 30 knots. The sky cover went from being just a few scattered clouds to a broken sky with these cumuliform clouds shown below moving rapidly through the region.

These cumuliform-type clouds were the result of a strong convective outflow boundary that moved through Fort Mill, South Carolina.  [Courtesy: Scott Dennstaedt]

As mentioned earlier, a gust front moving away from thunderstorms is a low-level event that can contain strong updrafts and downdrafts. The graph shown below is a time series, plotting the upward and downward motion or vertical velocity in a strong gust front as it moves over a particular point on the ground. 

The top half of the graph is upward motion and the bottom half is downward motion. Time increases from left to right. As the gust front approaches, the vertical velocity of the air upward increases quickly over a one- or two-minute period. While the maximum vertical velocities vary with height in the outflow, a common maximum number seen is 10 meters per second (m/s) at about 1.4 kilometers or 4,500 feet agl (25 knots is roughly 12 m/s for reference). 

As the gust front moves through, the velocities abruptly switch from an upward to a downward motion, creating strong wind gusts at the surface. Most outflow boundaries don’t extend above about 2 kilometers or 6,500 feet agl. What is remarkable is that upward-to-downward motion changes in just about 30 seconds over the ground point where this was observed. But imagine flying an aircraft at 150 knots through this— the up-and-down exchange will happen in just a few seconds, producing a jarring turbulence event.

This vertical sounding sensor graph depicts the change of the air velocity in the vertical over a particular location. Notice as the outflow boundary moves through the sensor array that it is first met with an updraft and followed by a downdraft. [Courtesy: Scott Dennstaedt]   

Just in case you were wondering, gust fronts are conveniently filtered out by your datalink weather broadcasts as shown below for XM-delivered satellite weather. This is because the broadcast only provides returns from actual areas of precipitation. Often outflow boundaries or gust fronts produce low reflectivity returns that fall below the threshold used to filter out other clutter not associated with actual areas of precipitation. 

When in flight, pay particular attention to surface observations, looking for strong, gusty winds, before attempting a landing at an airport when storms are approaching. 

It is common to have outflow boundaries and gust fronts filtered out of radar mosaic from datalink weather broadcasts. Shown in the upper left is the unfiltered image from the Greenville-Spartanburg NEXRAD Doppler weather radar. It has been filtered out of the XM-delivered broadcast. [Courtesy: Scott Dennstaedt]

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Should I File an Initial Approach Fix? https://www.flyingmag.com/should-i-file-an-initial-approach-fix/ https://www.flyingmag.com/should-i-file-an-initial-approach-fix/#comments Wed, 24 Apr 2024 14:03:44 +0000 https://www.flyingmag.com/?p=201327 After checking the weather, select an approach and file to an initial approach fix for it.

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Question: I am working on my instrument rating, and I have a question about filing to another airport. One of the CFIIs I fly with told me to file to the airport but not a particular fix because it’s really up to ATC to decide what the pilot should do. Another CFII told me to check the weather, see what the flow is, and file to an initial approach fix for an approach in use. Who is correct?

Answer: I advocate checking the weather and seeing what approaches are being supported by the conditions, then select an approach and file to an Initial Approach Fix (IAF) for that approach.

The reason? Because you lose your comms en route or before you are cleared for the approach, you will be following the AVE F procedure, which states that in the event of loss of communication you will fly one of the four: the heading you were assigned, vectored to, told to expect or filed to. If you are operating on an IFR flight plan, you should have at least one of these. This is what ATC expects you to do, so they will be protecting that airspace at the fix you filed to.

If you simply fly to the airport and the airport has multiple instrument approaches and multiple IAFs, ATC is going to have a more difficult time protecting the airspace. It will be like Whac-a-Mole with airplanes. If you file to a particular IAF, and they see a target squawking 7600 at that fix, they will have a pretty good idea that’s you. Make sure you continue to transmit in the blind – this means you make appropriate radio calls and position reports although you cannot hear them reply.

Bonus move: Adjust time en route by five minutes. For example, if it will take 23 minutes to get to the fix, file it as 17 minutes because that way you won’t have to wait for time to elapse in order to shoot the approach. 

Remember, you are requesting an approach when you file your flight plan. ATC is not obligated to grant your request, which is why you should have your approach binder with you (in either paper or electronic form). So if you are assigned something other than you filed, you will be prepared to fly what is offered.

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