Answer: There are many observed cases of lightning strikes to aircraft inside or near clouds that had not previously produced natural lightning. Studies show that about 90 percent of the lightning strikes to aircraft are thought to be initiated by the presence of the aircraft itself. The scary statistic, however, is that 40 percent of all discharges involving airborne aircraft occurred in areas where no thunderstorms were reported.

Apollo 12

One of the more famous cases of aircraft-initiated lightning is the Apollo 12 launch at the Kennedy Space Center, Florida, in November 1969. The Saturn V rocket was struck not once but twice on its way into orbit.

According to the 1970 NASA findings, other than these two strikes, there was no other lightning activity reported six hours before or six hours after the launch. At the time of the launch, a cold front was moving south into the launch area. Broken towering cumulus topping out at 23,000 feet with light to moderate rain showers were reported.

Rarely Fatal

Damage to airborne aircraft struck by lightning includes minor pitting or scarring to the aircraft’s skin to complete destruction of the aircraft.

Besides direct damage at the point of entry and/or exit, indirect effects that include the loss of VHF communication, loss of navigation equipment, and loss of instrument panel gauges are also possible.

In 1963, a Pan American Airlines Boeing 707 over Elkton, Maryland, was struck by lightning while in a holding pattern at 5,000 feet. The outermost fuel tank in the left wing exploded causing two other fuel tanks to follow suit. There were no survivors.  

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It’s certainly true that a catastrophic accident such as this is extremely rare, but lightning strikes to aircraft are more common than you might imagine—most of which are aircraft-initiated strikes.

Based on compiled data it is estimated that in the U.S. a commercial airliner is struck once for every 3,000 hours flown. That’s an equivalent of about one strike each year. 

Melting Level

While aircraft-initiated lightning is still being actively studied, there are a few important characteristics to consider.

Based on the current research, it doesn’t take flying in or near a mature thunderstorm to become the victim of a lightning strike. The mere presence of the aircraft in an environment conducive to an electrical discharge is all that is necessary.

Most of the aircraft-initiated lightning strikes occur when the aircraft is flying at or near the melting level (0 degrees Celsius). The preferred temperatures include a range from plus-3 C to minus-5 C, with the highest number of incidents occurring right at the melting level.  

A few of the strikes down low are the result of an aircraft intercepting a lightning strike in progress. Essentially, this is the case of being in the wrong place at the wrong time.

On the other hand, aircraft-initiated strikes are observed the most are between 3 km and 5 km or 10,000 to 16,000 feet during the warm season. Once again, temperature is a key factor. The melting level that typically occurs is in this same range of altitudes throughout the summer months.  

Low-Topped Convection

In general, natural lightning in deep, moist convection doesn’t form until the tops of the storm build well above the melting level.

For lightning to form, three ingredients must be simultaneously present. These include vapor-born ice crystals, graupel, and supercooled liquid water. If any one of these three is missing in sufficient quantities, natural lightning doesn’t generally occur, but this not to say the cloud is void of all electrical activity—some still remains.    

Therefore, an aircraft-initiated lightning strike typically occurs within local air mass instability within low-topped convection.

Often low-topped convection doesn’t produce natural lightning. The updrafts are rather weak in comparison to those that do produce lightning. Consequently, the updrafts do not carry enough supercooled liquid water into the upper part of the cloud where it is needed. 

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Clouds and Precipitation

An overwhelming number of lightning strikes occur within the cloud itself. Only a very small percentage of strikes occur outside of the cloud boundary or below the cloud.

Here’s the key: A very large percentage of the strikes occur within precipitation to include rain, snow, snow grains, ice pellets, and hail. It is not uncommon to find a mixture of these near the melting level. 

Keep Your Distance?

The FAA encourages all pilots to keep a safe distance from an active thunderstorm for obvious reasons.

Unfortunately, this practice alone isn’t quite enough. Even when thunderstorms (natural lightning) are not occurring or expected to occur, an aircraft-initiated lightning strike can still be a risk.

In order to avoid an encounter with lightning, the best advice is to remain in cloud-free air whenever possible, especially when the atmosphere is conditionally unstable and capable of producing marginally deep, moist convection extending well above the melting level.

While it may be difficult, the best advice is to operate outside of areas of precipitation and minimize your time in clouds and precipitation near the melting level.

The post How Can an Aircraft Get Struck by Lightning Without a Close Thunderstorm? appeared first on FLYING Magazine.

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.

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 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.

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.

The post Is Sferics Equipment Still Needed in the Cockpit? appeared first on FLYING Magazine.

Answer: Some ASOS sites do have a single-site lightning sensor in the array. If there isn’t a lightning sensor at the site, it is still possible for the ASOS to report lightning. For FAA-sponsored ASOS sites without a lightning sensor, lightning data is made available to the ASOS through the automated lightning detection and ranging system (ALDARS), which is a ground-based lightning detection system. ALDARS is not coresident with the sensor and sends the data to the ASOS. Here’s how it all works at a simplified level.

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Without a human observer logged in to the ASOS terminal, it will format a METAR or SPECI (special observation) for lightning in one of three ways: TS, VCTS, or lightning in the distance.

1. If the cloud-to-ground lightning strike is detected within 5 miles of the ASOS (usually within the airport’s terminal area), the ASOS will make a special observation (SPECI) and carry “TS” in the body of the special observation in the present weather field. If precipitation, such as rain or freezing rain, is also detected by the sensor array, the observation will include RA (or perhaps freezing rain or drizzle) along with the precipitation intensity (e.g., +TSRA for heavy rain and thunderstorms). “TS” will continue to be carried in the present weather field in subsequent observations until no cloud-to-ground lightning strikes are observed for a 15-minute period within that 5-mile radius. At that time, the ASOS will make a second SPECI observation and officially end the thunderstorm (removes the TS from the METAR).

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2. If the cloud-to-ground lightning strike is between 5 miles and 10 miles of the ASOS (the vicinity of the terminal area), the ASOS will make a SPECI observation and carry “VCTS” in the body of the observation in the present weather field. “VCTS” will continue to be carried in the present weather field in subsequent METAR observations until no cloud-to-ground lightning strikes are observed for a 15-minute period in the vicinity. At that time, the ASOS will make a SPECI and officially end the report of thunderstorms in the airport’s vicinity.

3. Separate from above, or independently, if the cloud-to-ground lightning strike is between 10 miles and 30 miles of the ASOS, the ASOS will carry a “LTG DSNT XX” remark, indicating distant lightning, with “XX” being the direction of the lightning in octants. This will be appended as appropriate on all SPECI and/or METAR observations.

For stations with a human observer logged into the ASOS terminal, the observation can be overridden or augmented to include adding remarks, such as FRQ LTGICCG OHD TS OHD MOV NE, which translates to frequent (FRQ) lightning (LGT) in clouds (IC) and cloud-to-ground (CG) overhead (OHD) with thunderstorms (TS) overhead (OHD) and moving (MOV) to the northeast (NE). Lastly, in the remarks of the METAR or SPECI, you will see a group that provides the exact time the thunderstorm begins and ends, such as TSB0159E30, which means the thunderstorm began (TSB) at 0159Z and ended (E) at 30 minutes after the next hour or 0230Z.

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.

The post Does ASOS Have a Built-in Lightning Detection? appeared first on FLYING Magazine.

U.S. 7th Fleet’s Task Force (CTF) 75 and Naval Sea Systems Command (NAVSEA) launched the salvage effort in late January after a Navy pilot ejected during a routine flight operation aboard the USS Carl Vinson and the fighter jet assigned to the Carrier Air Wing (CVW) 2 plunged into the ocean.

The aircraft was located about 12,400 feet below the water’s surface. A recovery team from CTF 75 and the NAVSEA’s Supervisor of Salvage and Diving (SUPSALV) March 2 using the diving support construction vessel (DSCV) Picasso, the Navy said Thursday.

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As part of the operation, the recovery team used a CURV-21 remotely operated vehicle to attach specialized rigging and lift lines to the aircraft. The F-35 was then hoisted out of the sea and onboard the Picasso by the ship’s crane, the Navy said.

“The task force’s expertise in rapid, scalable command, control, and communications, agile logistics, organic security, and explosive ordnance disposal was the most flexible choice for the fleet commander to respond in a timely manner,” CTF 75 Commodore, Capt. Gareth Healy, said in a statement. “Ultimately, this deliberate approach resulted in the correct capabilities conducting recovery operations within 37 days of the incident.”

Recovering the remains of the advanced stealth fighter from international waters before other countries—namely China—attempted to do so was a priority for the Navy, observers noted following the January 24 incident.

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China would likely try to find and survey the wreckage site through the use of submarines and deep diving submersibles, Carl Schuster, a former director of operations at the U.S. Pacific Command’s Joint Intelligence Center in Hawaii, told CNN at the time. According to Schuster, China could have potentially attempted to make a claim for the salvage rights based on its South China Sea territorial claims. 

The remains of the F-35 will be transported to a nearby military installation for inspection as part of an ongoing investigation into the incident, the Navy said.

The post Navy Recovers F-35C Sunk In South China Sea In ‘Landing Mishap’ appeared first on FLYING Magazine.