Print Version

Table of Contents

Collapse Menu | Expand Menu

Introduction

Steve Lehmann, scientific  support coordinator from the National Oceanic and Atmospheric Administration, surveys an oil spill sheen on board a Coast Guard HH-60 rescue helicopter from Air Station Cape Cod. The mission of the overflight was to look for any impact from the estimated 14,700 gallons of oil released into the water when Bouchard Barge  No. 120 ran aground Sunday. USCG photo by PA2 Matthew Belson

Aircrews and pilots are frequently the first to see oil spills on water. They provide critical eyes in the sky for U.S. Coast Guard (USCG) response teams and NOAA's Office of Response and Restoration. Oil spill responders use a common terminology for describing and reporting oil spills. This lesson teaches aircrews how to identify, describe, and report spills using that terminology. Misidentifying natural events as oil spills is a common, and sometimes expensive, mistake. This lesson also points out common false positives when trying to identify oil spills.

Coast Guard aircrews have lots of experience flying and spotting people and objects from aircraft, but they may not be familiar with key spill response terminology and information that Coast Guard pollution responders would find most useful during an oil spill. While our primary audience for this lesson is aircrews, other flight crew members may find this lesson useful, including personnel from Incident Management Divisions and the Coast Guard Auxiliary.

In the event that a spill has been reported, pilots and aircrews may find themselves supporting a mission with trained oil spill observers on board. This lesson also provides information on how to work most effectively with those observers to ensure a successful mission.

Objectives

Photo collage of oil spills

At the end of this lesson, you will be able to do the following:

  • Accurately report oil sightings using standard terminology
  • Provide the critical information most useful to pollution responders
  • Recognize false positives
  • Work effectively with trained observers

The Job Aid

Open Water Oil Identification Job Aid for Aerial Observation

Further resources, including a checklist for reporting oil spills suitable for aircrews, can be found at the website:

Job Aids for Spill Response

Cover for the NOAA publication Open Water Oil Identification Job Aid for Aerial Observations

The Office of Response and Restoration of the National Ocean Service has summarized the critical information in this lesson into a Job Aid, which can be accessed using the link above. Durable, laminated copies can also be ordered and kept in a place that is available for use in your aircraft.

Critical Information

When you see what looks like an oil spill, the critical information to report includes a description of what you're seeing and its location using terminology that's most useful to pollution responders.

Location

Leaking oil drum along shore after Hurricane Sandy

First-and-foremost, responders want to know the location of the main area(s) of oil. In addition to the main area, responders will want to know the location of the spill's source and the spill's leading edge, or the location farthest downwind or down-current from the source. If you can identify these features, report their locations. Here, a leaking tank or drum is located near shore and the surface oil is trailing parallel to shore, off the picture to the right. In this case, the location of the source (the drum) is obviously a very important piece of information about the spill.

Reporting Location

Portion of an aeronautical chart for the south end of the Mississippi River Delta with the location of a hypothetical oil spill.

When reporting an oil spill, convey the location in two ways: (1) as a latitude/longitude and (2) as a distance and direction to a landmark. The redundant reporting provides a check to ensure that there were no errors in transmitting or transcribing the reported location. In the example shown here, the spill is located 13 miles WSW (242) from the south end of Southwest Pass.

One source of error in reporting is the format for latitude and longitude. These are commonly reported in three different formats:

  • Decimal degrees, commonly used in GIS (for example, 28.813N, 089.636W)
  • Degrees and decimal minutes, typically used by aircrews (for example, 28 49.16'N, 089 38.16'W)
  • Degrees, minutes, seconds (for example, 28 49' 10''N, 089 38' 10''W)

So that it's not confusing to the person receiving your report, be very specific about the format you are using when you report these locations. Once started, stay consistent and use the same format. Don't switch formats in the same report.

Question

Portion of an aeronautical chart for Prince William Sound, Alaska, with the location of a hypothetical oil spill.

This chart shows the location of a small oil slick in Prince William Sound, Alaska. Which of the following is the best description of its location? (Choose the best answer.)

The correct answer is (c) 6047.6'N, 14716.3'W and 5 miles south of Glacier Island.

Please make a selection.

Description

Aerial photo of dark oil streamers near shore

When describing an oil slick, communicate the four following properties:

  1. Dimensions
  2. Orientation
  3. Color
  4. Distribution/Structure

Dimensions: Slicks vary greatly in size, from feet to miles. When describing dimensions be clear about the units you are using and stick with the units you choose.

Orientation: Some slicks are round or oval, but many more stretch out into long narrow bands. When slicks are elongated, it helps responders to know the orientation of the long axis.

Color or Appearance: The color or appearance of an oil slick depends on several factors, including oil type, weather, and visibility, but most importantly, it depends on the thickness of the oil on the water. Consequently, the appearance of the oil slick tells responders a great deal about how recoverable the oil is. Describing color and appearance are covered in greater detail later in the lesson.

Distribution or Structure: Oil on water is affected by currents, wind, and other environmental factors that result in different structures, such as patches, streamers, windrows, and convergence lines. Describing distribution and structure is covered in greater detail later in the lesson.

Other Features

Aerial view of streamers of emulsified oil with dolphin pod

In addition to the oil slick, the location of other features may also prove valuable to responders, but is not as critical. For example, the status of the source: Is it a listing ship or an offshore oil platform? Do you see oil booms, skimmers, or response crews? What are the wind, sea state, and visibility conditions? For coastal locations, can you discern the tide level or currents? If there is a significant wildlife presence, what type of creatures are they and how many are there?

All of these factors help responders assess the situation and respond accordingly.

How to Report an Oil Spill

If you do encounter an oil spill while flying, and it is possible given your flight duties, it is best to call in an immediate verbal report, directed to the local Incident Management Division (IMD). At the least, you should include the location, size, and whether you see a sheen or dark or emulsified oil.

Any documentation you can gather is very helpful, particularly photos and/or video of the spill. When you land, forward that information with a written report to the IMD. The more details and documentation the better, but do what time and operations allow.

Color/Appearance

Sheens from oil spots in parking lot

As you can see by this photo of gasoline drops on a wet parking lot, only a small amount of oil can create a visually conspicuous sheen on water because the oil spreads out into a very thin layer. The thickness of the oil layer determines its color and recoverability.

Schematic diagram showing the Relationship Between Thickness and Color for Oil on Water

This graphic shows the relative thickness for the different colors of oil slicks with increasing thickness. The primary distinction is between sheens, which are typically not recoverable, and darker oils, which may be recoverable. A trained observer may further distinguish different classes of sheens or darker oils. These are the standard descriptors of color for reporting oil spills. As an aircrew member verbally reporting an oil observation, the most important information for responders to know is whether you are seeing sheen or darker oil, rather than worrying about specific color distinctions of either.

When you see a sheen (silver, rainbow, or metallic) you are looking at something that is thinner than household aluminum foil. This is thousandths of an inch thick. Dark oil slicks, in contrast, are thicker. Dark oil slicks may be as thick as a sheet of copier paper, but can be thinner. Although thicker than a sheen, this too is still thousandths of an inch thick. Thus, even though sheens might cover a larger area, most of the spilled oil volume will be within the darker oil portions of the slick.

Regardless of thickness, all sheens and slicks should be reported. By law, all sheens are reportable and may incur a penalty. Furthermore, the public will notice and report sheens. Having an accurate description from a trained aircrew helps the Coast Guard respond to these reports.

Observing Sheens

From the air, sheens are most easily detected from the side, with a highly oblique view, but their color is most accurately seen from overhead. Sheen color can be influenced by several factors, including the reflection of the sky, position of the sun, underlying water color, sea state, and wind conditions. Some of the thinnest sheens may become transparent and disappear when you fly directly overhead. If that occurs, it helps to look for a source area, or region with a darker color, such as a rainbow sheen, to confirm that the sheen represents oil and not a naturally occurring false positive.

Some sheen colors can be difficult to discern. A metallic sheen, in particular, can be difficult to distinguish from a silver sheen. If you see a sheen and can divert to get a better look, fly overhead to determine the color. If you cannot divert, report the color you see.

There are multiple types of sheens on the surface of most waters, many of them transparent and originating from biogenic sources or simply from wind patches. Air crews are familiar with seeing those types of sheens. Oil spills create transparent sheens that can be quite large in extent. For the purposes of reporting oil spills, the sheens to be concerned with are the ones that have some color associated with them. Those are the sheens that may persist and require a response action.

Sheen Examples

Aerial view of partially submerged F/V Buccaneer and associated sheen. Point Mugu, CA

Silver sheens are the thinnest of reportable sheens. Here we see a silver sheen surrounding a capsized vessel with a recovery vessel standing by. We can also see a slightly darker region in the lower-right portion of the slick.

Aerial view of tugboat and rainbow sheen. Deepwater Horizon Incident.

Slightly thicker sheens display a fairly obvious rainbow of colors, like the familiar sheen we see in puddles around gas stations.

Aerial view of metallic sheen. Exxon Valdez oil spill

The thickest sheens display a metallic color. In this example, we can see rainbow sheen around the edges of the thicker metallic sheen.

Darker Oils

Schematic diagram showing the Relationship Between Thickness and Color for Oil on Water

Oil spills appearing as darker oils are thick enough to display at least some of the true color of the oil. However, transitional dark oil can be a problematic descriptor. Its use is best left to trained observers. Use only the terms "dark" or "emulsified" oil. These terms should alert oil spill responders that your aircrew is observing more than just an oil sheen.

Dark Oil

Aerial view of dark oil on the Mississippi River. M/V Westchester oil spill

Dark oil is usually pretty obvious. It retains its original color, which may vary from black to different shades of brown. Here we see a spill of black crude oil in the muddy brown water of the Mississippi River.

Emulsified Oil

Aerial view of emulsified oil and skimmer. Deepwater Horizon incident

Under certain conditions, water droplets become mixed with the oil to form emulsified oil, sometimes called mousse. The color of emulsified oil can vary greatly, from yellow to dull brown to bright red. This photo shows some of the variability seen in emulsified oil from the Deepwater Horizon incident.

Aerial view of emulsified oil. Ixtoc 1 oil spill

This aerial photo shows emulsified oil in shades of brown to tan from the 1979 Ixtoc 1 oil spill in the Gulf of Mexico.

Aerial view of emulsified oil changing to dark oil as it degasses and dewaters. Bayou Perot well blowout

This is an interesting example of how the same oil takes on many different colors, depending on how thick and emulsified it is. This is from a wellhead blowout in Bayou Perot, Louisiana. There is unstable emulsion being developed as the crude oil is released, due to pressure. Once the crude oil hits the boom, the emulsion breaks as the energy that was keeping it emulsified is released. It then shows it's true dark color.

Questions

Question 1

What color oil is present in this photo? (Choose all that apply.)

Aerial view of emulsified oil. Deepwater Horizon incident

The correct answers are (c) emulsified oil, with some (a) silver sheen above the emulsified oil.

Please make a selection.

Question 2

What color oil is present in this photo? (Choose all that apply.)

Rainbow sheen

The correct answer is (a) rainbow sheen.

Please make a selection.

Question 3

What color oil is present in this photo? (Choose all that apply.)

Aerial view of dark oil streamers and metallic sheen leaking from the American Trader, California.

The correct answers are (a) metallic sheen and (b) dark oil.

Please make a selection.

Question 4

What color oil is present in this photo? (Choose all that apply.)

Aerial view of dark oil and boom on the Mississippi River. M/V Westchester oil spill

The correct answers are (b) dark oil, with (a) silver sheen further from shore. There are 2 additional things to note here: (1) while the boom is generally doing a good job of containing the oil, some is getting past it along the shoreline, and (2) the shadow of the helicopter in the lower right provides scale.

Please make a selection.

Question 5

What color oil is present in this photo? (Choose all that apply.)

Aerial view rainbow sheen and oil skimmer

The correct answer is (a) rainbow sheen surrounding areas of metallic sheen. The dark path from upper-left to lower-right is likely due to a boat wake.

Please make a selection.

Question 6

What color oil is present in this photo? (Choose all that apply.)

Aerial view of silver sheen streamer. Prince William Sound, Alaska

The correct answer is (a) silver sheen. However, due to the low angle of view, this would require an overhead view for confirmation.

Please make a selection.

Structure/Distribution

We've talked about oil color and how it can indicate thickness   recoverability. With time, wind, and waves, a continuous oil slick can break up and evolve into progressively smaller slicks. The structure describes how these oil slicks are distributed across the water's surface.

The standard descriptors for structure include the following:

  • Streamers
  • Convergence line
  • Windrows
  • Patches
  • Tarballs
  • No structure random eddies and swirls a catchall that isn't one of the others

Next, we describe each of these structures.

Streamers

Aerial view of streamer of rainbow sheen from oil facility after Hurrican Katrina

Streamers are long, narrow bands of oil with clean water on each side. This photo shows a streamer of sheens coming off of an oil production facility damaged by Hurricane Katrina.

Streamers may occur as a single band, as shown here, or...

Streamers of emulsified oil with sheens. Ixtoc 1

in multiple bands. This photo shows multiple streamers of emulsified oil from the Ixtoc 1 oil spill.

Streamers of oil are often seen originating from an oil source or from larger oil slicks. They also form where an obstruction, like a ship or pilings, disrupts and splits the flow of surface oil.

Streamers may be caused by wind and/or currents and range from hundreds of yards to several miles in length.

Convergence Line

Aerial view of a plane releasing dispersant over emulsified oil in a convergence line.

Convergence lines can form where one water mass meets another. They can result from differences in temperature and/or salinity or they can form where currents flow over an abrupt change in bathymetry. Oil and other floating materials accumulate at the surface along convergence lines, typically in a long, continuous ribbon. Such zones may be several miles in length. Here we see emulsified oil concentrated in a convergence line.

Convergence lines are important because:

  • Oil accumulates there. They are a prime target for responders.
  • They provide important constraints for oil spill trajectory models.
  • Wildlife is naturally drawn to convergence lines. Algae, rafting birds, and smaller animals drift into them, attracting larger animals, including predatory fish, turtles, and seabirds.
Aerial view of a convergence line marked by sea foam.

While convergence lines are typically fairly straight, they can also meander around quite a bit. Here the convergence line between muddy water on the left and blue water on the right is marked by a meandering line of sea foam.

Windrows

Windrows of silver sheen on the Columbia River, Washington.

This photo from the Columbia River Gorge shows a pattern that we see quite often. It looks like many regularly spaced streamers. These bands are called windrows, and as you might expect, this structure is caused by the wind. Windrows line up roughly parallel to the local wind direction.

Windrows in emulsified oil. Deepwater Horizon incident

Windrows concentrate oil into bands, whether it's sheen, as we saw previously, or dark or emulsified oil, like the example here.

Patches

Aerial view of a patch of rainbow to silver sheen off the coast of Venice, La.

A patch is an isolated area of oil, separate from the main area or areas of an oil slick. In the absence of wind or currents, oil on water tends to form patches. Patches range in size from yards to hundreds of yards. Unlike streamers, they are not elongated and may not lead back to the source.

This photo shows an isolated patch of sheen, perhaps a few hundred yards in length, surrounded by water.

Patches of emulsified oil. Deepwater Horizon incident

Small patches of dark or emulsified oil, like the one shown here, may be deformed by wind or currents, resulting in a comma or comet shape. Also, note the reflections off of the window.

Patches of oil rising to the surface from the sunken tanker Solar 1, Philippines

Sometimes oil from a submerged source rises to the surface as a series of discrete drops that spread out, or "blossom" into patches at the surface.

Tarballs

A close-up of a tarball found on the beach in Dauphin Island, Alabama (May 13, 2010). Credit: NOAA.

Tarballs are discrete, and usually pliable, globules of weathered oil. Tarballs vary in size from less than an inch to 8-12 inches across (a few centimeters to 2030 centimeters).

A close-up of floating tarballs with an associated sheen

This photo, taken from a ship, shows floating tarballs with associated sheens. While tarballs are rarely visible from the air, you might be able to see the sheen emanating from a cluster of them. While they may not be visible from the air, tarballs can accumulate on beaches and have a significant impact.

No Structure

This video shows random eddies or swirls of dark oil with no discernible pattern. We call this distribution "No Structure". It reflects sluggish random currents. No structure also provides a structure/distribution term for oil that doesn't neatly fall into the other categories.

Dark oil and sheens with no structure. Deepwater Horizon incident

This photo shows an example of no structure from the Deepwater Horizon incident.

Questions

Question 1

For this photo, describe the oil spill. (Choose all that apply.)

Boom is deployed across the Calumet Sag Channel where a sheen is spotted from an overflight by an aircrew from Coast Guard Air Station Traverse City, Mich., Aug. 27, 2012.The sheen is from a jet fuel spill caused by a ruptured pipeline from Westshore Pipeline near Palos Height, Ill. U.S. Coast Guard photo by Petty Officer 3nd Class John Schleicher.

Color/Appearance:

Structure/Distribution:

The correct answer is a (1) sheen (a) streamer. (Jet fuel spill, Calumet River, Illinois)

Please make a selection.

Question 2

For this photo, describe the oil spill. (Choose all that apply.)

Aerial view of emulsified oil. Deepwater Horizon incident

Color/Appearance:

Structure/Distribution:

The correct answer is (3) emulsified oil at a (b) convergence line. Also note the (c) windrows of (1) silver sheen both below the convergence line and (a) streamers of sheen and emulsified oil above. (Deepwater Horizon incident)

Please make a selection.

Question 3

For this photo, describe the oil spill. (Choose all that apply.)

Patches of oil rising to the surface from the sunken tanker Solar 1, Philippines

Color/Appearance:

Structure/Distribution:

The correct answer is (2) dark oil in (d) patches, including blossoms, with (1) silver to rainbow sheens. (Sunken tanker Solar 1, Philippines)

Please make a selection.

Question 4

For this photo, describe the oil spill. (Choose all that apply.)

Patch of emulsified oil in a field of silver sheen windrows. AMOCO CADIZ grounding and oil spill, Brittany, France, March 1978

Color/Appearance:

Structure/Distribution:

The correct answer is a (3) emulsified oil (d) patch in a field of (1) silver sheen (c) windrows. (Amoco Cadiz oil spill, north coast of France)

Please make a selection.

Question 5

For this photo, describe the oil spill. (Choose all that apply.)

Windrows of silver sheen 40 miles off of Galveston Oct. 21, 2009, after an estimated 18,000 gallons of fuel oil were spilled from the tanker Krymsk Oct. 20, 2009.

Color/Appearance:

Structure/Distribution:

The correct answer is (1) silver sheen (c) windrows, with some (2) dark oil in the lower left corner. (M/V Krymsk oil spill near Galveston, Texas)

Please make a selection.

Question 6

For this photo, describe the oil spill. (Choose all that apply.)

Dark oil and metallic sheen with no structure. Deepwater Horizon incident.

Color/Appearance:

Structure/Distribution:

The correct answer is (2) dark oil and (1) sheen with (f) no structure. (Deepwater Horizon incident)

Please make a selection.

False Positives

Photo collage of common oil spill false positives

At this point, you should have a good idea of what oil looks like from the air and how to describe it using standard terminology. But, what if what you see is not oil? Some natural phenomenon may appear to be oil at first glance, but are rather "false positives".

As aviators you're likely very familiar with false positives, especially if you do search and rescue. A crab trap buoy or somebody's lost float from the beach can mimic a person in the water, or possibly a life raft.

Some false positives are difficult to distinguish from oil except with a low and slow overflight. Others may require positive identification. False positives are relatively common. For example, during the response to the Exxon Valdez oil spill in Alaska, 25% of NOAA overflights were spent determining that reported oil sightings were really false positives. Many of these reports came from Hinchinbrook Island, but the island was never oiled. It happens.

If you're not sure whether it's oil or not, that's okay. It should still be reported. Alert your (IMD regarding items that could be perceived as oil, but are likely not oil. Just let them know that you're not sure. They may have a professional observer go out.

In this section we look at many things that could potentially be reported as oil spills. Note that some of them are region-specific. For example, kelp beds on the West Coast or floating sargassum weed in the Gulf of Mexico.

Sargassum

Click the A and B tabs to compare these two photos. One shows sargassum, a free-floating algae, in the Gulf of Mexico. The other shows patches of emulsified oil. Which photo shows the sargassum? (Choose the best answer.)

A

Sargassum patches in the Gulf of Mexico

B

Emulsified oil patches in the Gulf of Mexico

The correct answer is Photo A shows sargassum in a patch several meters across. However, given just the view in the photos, there's really no way to tell one from the other.

Please make a selection.

Sargassum - 2

Is this patches of emulsified oil or sargassum? (Choose the best answer.)

Patches of emulsified oil in the Gulf of Mexico

The correct answer is (a) patches of emulsified oil. In this case we can see a silver sheen trailing off of the patches, indicating the presence of oil.

Sargassum can form large patches, streamers, and windrows. It frequently collects in convergence lines. In the event of an oil spill, oiled sargassum is a common occurrence, especially in the Gulf of Mexico.

Please make a selection.

Algal Blooms

Algal bloom in Chesapeake Bay

Algal blooms are among the more difficult false positives. Depending on the algae, they form a wide range of colors, including dark brown resembling dark oil and shades of red and yellow resembling emulsified oil. They may appear at the surface or just below.

Puget Sound

Algal bloom on Puget Sound, Wahington
Algal bloom on Puget Sound, Washington

These photos show two different types of algal blooms that occur in Puget Sound and resemble emulsified oil.

Kelp

On the West Coast large kelp beds just offshore frequently mimic oil spills. Click the A and B tabs to compare the photos. One of these photos shows kelp beds and the other shows dark oil near shore. Which of the photos do you think shows kelp? (Choose the best answer.)

A

Kelp in Southern California

B

Dark oil in surf. American Trader oil spill, Southern California

The correct answer is Photo A shows kelp. Photo B shows dark oil in the surf.

One way to tell kelp from oil is that kelp may sway back and forth with the swell, but won't move because kelp is rooted to the seafloor.

Please make a selection.

Seagrass

Aerial photo of seagrass beds, Florida

Seagrass beds can resemble submerged oil. Again, it helps to be familiar with the local area when looking for and reporting oil spills.

Cloud Shadows

Photo of cloud shadows on the ocean. Georgia Strait, Canada.

Dark patches on the water may result from dark oil, or in this case, from cloud shadows. A quick check for clouds and the angle of the sun should confirm which of the two you're seeing. Also, clouds tend to move and/or change shape fairly quickly. Oil slicks do not.

Marsh Peat

Peat from marshes collecting along beaches. Gulf Coast

Along the Gulf Coast, peaty material eroded from marshes and deposited along beaches strongly resembles dark oil. Even experienced observers have required ground-truthing to confirm that this is not oil.

Fish Schools

Photo of school of anchovies taken from top of sea cliff. La Jolla, Southern California
Photo of school of anchovies taken from top of sea cliff. La Jolla, Southern California

Photos from NOAA/SWFSC/Northern Anchovy Research

Schools of bait fish, like herring or anchovies, can sometimes form dark masses easily mistaken for oil. To distinguish fish schools from submerged oil, continue to watch them. Fish schools will move and change shape relatively quickly.

Jellyfish

Jellyfish frequently congregate in large masses. Close-up, they look like oil "blossoms". Click the A and B tabs to compare the two photos. One of these photos shows jellyfish, the other shows oil blossoms. Which photo shows jellyfish? (Choose the best answer.)

A

Photo of patches of silver sheen "blossoming" at the surface above the sunken vessel TENYO MARU, Washington, July 1991

B

Photo of jellyfish taken from a dock in Japan

The correct answer is Photo B shows jellyfish. It shows a close-up taken from a dock. Photo A shows patches of oil from the Exxon Valdez oil spill.

Please make a selection.

Aerial View

Aerial view of streamers of Jellyfish in Puget Sound, Wahington
Aerial view of patches of Jellyfish in Puget Sound, Wahington

More distant views of jellyfish can appear like streamers or patches of silver sheen.

Black Marine Lichen

In Alaska, a black marine lichen that strongly resembles weathered oil commonly appears along rocky cliffs and beaches. It grows in the upper intertidal zone above the mean high high water mark. Click the A and B tabs to compare the two photos. Which one do you think shows an oiled shoreline? (Choose the best answer.)

A

Aerial photograph. Steep rock shoreline showing distinct banding for different species of marine algae and marine fauna at well-defined tidal levels.  Lynn Canal, Southeast Alaska

B

Photo of oiled rocky shoreline. Exxon Valdez oil spill, Alaska

The correct answer is Photo B shows an oiled shoreline from the Exxon Valdez oil spill in Prince William Sound, Alaska. Photo A shows black marine lichen, but no oil. The best clue here is the presence of other organisms below the black lichen that are not present in the oiled shoreline. If the tide level was higher, this might be completely obscured. The other visual clue is the strong demarcation line where the oil is attached to the rocky shoreline, versus the gradual spread of the lichen through the tide range. Black marine lichen was responsible for many false-positive reports during the Exxon Valdez incident.

Please make a selection.

Herring Spawn

Herring spawn forms long, pale streamers in shallow water that can be mistaken for silver sheen. Click the A and B tabs to compare the two photos. Which one do you think shows herring spawn? (Choose the best answer.)

A

KURE incident, Humboldt Bay, California, November 1997. Cleanup workers and supplies on an oil-covered beach in South Bay.

B

Photo of herring spawn in shallow water along a snowy coast in Alaska

The correct answer is Photo B shows herring spawn. Herring tend to spawn in the winter months and in this photo from Alaska you can see snow on shore. Photo A shows clean-up workers on an oiled beach with silver sheen along the shore.

Please make a selection.

Ashes

Ashes and charred debris can look remarkably like dark oil. Click the A and B tabs to compare the two photos. One shows oil stranded on a beach, the other ashes and charred debris. Which do you think is ashes? (Choose the best answer.)

A

Aerial photo of ashes and burn debris on a beach in Southern California

B

Photo of oil strandlines on a beach

The correct answer is Photo A shows ashes and burned debris on a beach in Southern California. The debris washed down to the coast during heavy rains several months after a large wildfire. This false positive looks so much like beached oil that it needed to be confirmed with ground observations.

Please make a selection.

Windrows

Aerial photo of windrows of ashes and burn debris in muddy water off of  Southern California

This photo shows windrows of ashes and debris floating in muddy water. Again, this would be a very difficult false positive.

Sediment Plume

Aerial photo of sediment plume at the mouth of the Elwha River, Washington

Sediment plumes can take on the reddish hue of emulsified oil.

Ice

Aerial photo of ice along shoreline

Ice forming in shallow water can also look like silver sheen if the lighting is right. Once again, be aware of your environment, especially in the first big freeze of the winter before ice becomes widespread.

Mussel beds

Aerial photo of mussel bed, Elanor Island, Prince William Sound, Alaska

Mussels can form large dark beds in the lower to mid intertidal zone, typically in wave-washed areas. However, on a calm day, they can be mistaken for submerged or stranded oil.

Practice Questions (Optional)

Now we've seen several examples of oil spills and false positives. If you're comfortable with what you've learned, you can proceed to the next section, Obstacles to Good Observations. If you'd like more practice, the following photos of oil spills and false positives will test your ability to identify and describe both.

Question 1

For this photo, describe the what you observe. (Choose all that apply.)

Aerial photo of a long lone streamer of emulsified oil. Deepwater Horizon incident, off the shore of Louisiana, May 5, 2010.

Color/Appearance:

Structure/Distribution:

The correct answer is a (b) streamer of (4) emulsified oil.

Please make a selection.

Question 2

For this photo, describe the what you observe. (Choose all that apply.)

Photo of patches of rainbow sheen "blossoming" at the surface above the sunken vessel TENYO MARU, Washington, July 1991

Color/Appearance:

Structure/Distribution:

The correct answer is (e) patches of (2) rainbow sheen.

Please make a selection.

Question 3

For this photo, describe the what you observe. (Choose all that apply.)

Peat from marshes collecting along beaches. Gulf Coast

Color/Appearance:

Structure/Distribution:

The correct answer is (1) and (a) false positive. This photo shows peat eroded from marshes in Louisiana.

Please make a selection.

Question 4

For this photo, describe the what you observe. (Choose all that apply.)

Aerial photo of a streamer of emulsified oil with an associated rainbow sheen.
MMS/USCG overflight on 23 June 2007 that show several portions of a slick composed of silver and rainbow sheen as well as what appears to be emulsified oil (photo credit, USCG).

Color/Appearance:

Structure/Distribution:

The correct answer is (2) rainbow sheen, emanating from a streamer of (1) sargassum. The sargassum could present an extremely difficult false positive for emulsified oil, especially with the sheening that is present.

Please make a selection.

Question 5

For this photo, describe the what you observe. (Choose all that apply.)

Aerial photo of a streamer of silver sheen, along with several false-positive cloud shadows. On November 18, 2006, NOAA ERD was notified of a mystery spill in the area of Main Pass, Breton Sound, LA.

Color/Appearance:

Structure/Distribution:

The correct answer is a (b) streamer of silver (2) sheen, along with several (1) false-positive cloud shadows. Also note that it appears we can see the source of the slick in the distance.

Please make a selection.

Question 6

For this photo, describe the what you observe. (Choose all that apply.)

Photo of floating tarballs taken from ship. M/V Athos oil spill, Delaware Bay

Color/Appearance:

Structure/Distribution:

The correct answer is (3) dark oil in (f) tarballs. No other structure is apparent. The photo was taken from a helicopter during an overflight of the Delaware River a day after the Athos oil spill near Philadelphia.

Please make a selection.

Question 7

For this photo, describe the what you observe. (Choose all that apply.)

Algal bloom in Chesapeake Bay

Color/Appearance:

Structure/Distribution:

The correct answer is (1) and (a) false positive. This photo shows an algal bloom in Chesapeake Bay.

Please make a selection.

Question 8

For this photo, describe the what you observe. (Choose all that apply.)

Aerial photo of metallic sheen with no structure. Deepwater Horizon incident.

Color/Appearance:

Structure/Distribution:

The correct answers are (2) metallic sheen with patches of (3) dark and/or (4) emulsified oil with (g) no structure.

Please make a selection.

Question 9

For this photo, describe the what you observe. (Choose all that apply.)

Aerial photo of streamers of silver, rainbow, and metallic sheen

Color/Appearance:

Structure/Distribution:

This photo shows three distinct (b) streamers with different (2) sheens: rainbow sheen (bottom), metallic sheen (middle), and silver sheen (top).

Please make a selection.

Question 10

For this photo, describe the what you observe. (Choose all that apply.)

Kelp in Southern California

Color/Appearance:

Structure/Distribution:

The correct answer is (1) and (a) false positive. This photo shows a very dark kelp bed in turbid water off the Southern California Coast.

Please make a selection.

Question 11

For this photo, describe the what you observe. (Choose all that apply.)

Aerial photograph. Steep rock shoreline showing distinct banding for different species of marine algae and marine fauna at well-defined tidal levels. Lynn Canal, Alaska

Color/Appearance:

Structure/Distribution:

The correct answer is (1) and (a) false positive. This photo shows marine black lichen from Southeast Alaska.

Please make a selection.

Question 12

For this photo, describe the what you observe. (Choose all that apply.)

Photo of school of anchovies taken from top of sea cliff. La Jolla, Southern California

Color/Appearance:

Structure/Distribution:

The correct answer is (1) and (a) false positive. This photo shows a fish school in Southern California.

Please make a selection.

Obstacles to Good Observations

Now that we've looked at the range of what oil spills look like from the air, let's look at factors that get in the way of good observations.

Seating

Photo of USCG observer looking for oil in the Gulf of Mexico from an HC-130 Hercules aircraft. Deepwater Horizon incident, July 22, 2010

Depending on the mission and aircraft configuration, people will be sitting in different places in the aircraft. Obviously, some seats offer better viewing, while other seats limit what is viewable. If the mission is an overflight looking for oil with a trained observer on board, then the observer should be seated in the best seat that the mission allows.

Lighting

Photo of glare from sun reflecting off water

Sun angle strongly affects what an observer can see. Low sun angle leads to glare and a high sun angle can lead to glint. Both conditions make observations and photography difficult. Looking toward the sun also increases reflections off of windows.

Sunglasses can profoundly alter what observers see, especially those with polarized lenses. Generally, polarized lenses make it easier to see light sheens. They may also prove useful for seeing darker oil within a large area of sheen; they cut the glare, revealing the darker oil. There are two downsides to polarized lenses: (1) they can lead to over-reporting of sheens, and (2) they can alter the observed sheen color. In general, sunglasses should only be used for spotting, lift them out of the way for collecting information on oil descriptors.

Sea State and Weather

During early December of 2004, a huge storm drove the floundering M/V Selendang Ayu onto the rocky shoals on the west side of Unalaska Island in the Aleutian Islands, Alaska. Here, the vessel broke in two, releasing more than 75 percent (337,000 gallons) of its total petroleum fuel load of IFO-380 and marine diesel. Nearly all the oil was driven onto the mostly rocky shorelines of Makushin and Skan Bays.

Environmental conditions can strongly affect your ability to observe oil spills.

  • Rough seas can make it hard to find oil and describe it. You may see darker oils but you're not likely to see sheen. However, sheens may "appear suddenly" after the seas lay down.
  • Conversely, very calm seas can make for apparent sheens where none actually exist.
  • Cloud cover, or anything else that reduces visibility, can impair your ability to observe oil on water.
  • Oil spills may appear much larger in calm conditions than in rough conditions.

Preparation

Photo of USCG aircrew

Good observations start with preparation, particularly training and planning. Hopefully, this lesson has prepared you as Coast Guard aircrews to make effective observations that are helpful to responders.

Working with Trained Observers

HC-130 Gulf of Mexico Overflight

 

This video shows crew members from Coast Guard Air Station Clearwater working with observers from the National Oceanic Atmospheric Administration on an overflight of the BP Deepwater Horizon Spill on June 30, 2010.

Preparation

A US Coast Guard HC-144 aircraft departs for a media support flight to document and plot the location of the Deepwater Horizon oil spill

Trained oil spill observers may come from many different agencies, including NOAA's Office of Response and Restoration, Coast Guard Incident Management Divisions and Strike Teams, as well as state agencies.

If you are a member of the flight crew and you are taking out a trained observer, there are several things you can do to make the mission efficient and effective.

In your pre-flight meeting, you should be prepared to discuss the following:

  • Mission objectives. Make sure everyone is clear on the mission objectives. Oil surveillance is often a dedicated single-mission flight or is the primary mission of a multi-mission flight.
  • Areas to cover. The trained observer should come with maps and waypoints and make them available to the aircrew.
  • Flight duration, proposed path, preferred altitude and speed, and reasonable deviations. Trained observers know their job and what it will take for the aircrew to provide them with the right viewing altitude, speed, viewing position, etc. However, the flight plan desired by the observer may exceed your aircraft limitations. Work with the observer. Let them know your flight limitations so that they can prioritize. Observers often request in-flight deviations to get a better view, to track an oil sheen to its source, or to determine the leading edge of a miles-long slick. That's okay, but only within acceptable safety limits.
  • Observers should also be aware that Coast Guard flights may be diverted for higher priority missions (for example, search and rescue) and need to abort the oil observation.
  • A safety briefing will also take place.

In addition, the flight crew should discuss the following:

  • Aircraft flight limitations
  • Possible mission constraints
  • On-site conditions, including local wind, sea state, and visibility.

Work with the observer to get them the information they need to perform their job.

Observer Needs

Photo of Steve Lehmann, scientific support coordinator from the National Oceanic and Atmospheric Administration, surveys the shoreline on board a Coast Guard HH-60 rescue helicopter from Air Station Cape Cod to look for any impact from the estimated 14,700 gallons of oil released into the water when Bouchard Barge No. 120 ran aground Sunday.

What does the trained and experienced observer need?

  1. They need a seat with high visibility. That might include a large window or seat near an open door. Observers are mission specialists. Getting them in good seating is important, even if somebody has to take a seat that they don't normally occupy.
  2. Observers need to have good communication with pilots, so they need a good headset.
  3. Observers need to work effectively with the aircrew and use terms everyone understands. It is important that everyone is on the same page regarding what units they're going to use for latitude and longitude. Often the observer will need to use a one format and the pilot will need to use something else. Just be clear what format you're using when you talk back and forth.
  4. Observers may have special gear that they wish to carry; for example, GPS, cameras, and maybe a tablet PC. Coast Guard policy has become fairly strict regarding portable electronic devices in its aircraft. The GPS and camera may be allowed, but not necessarily. Observers should definitely check ahead of time as much as possible with the Coast Guard to make sure their gear will be allowed on Coast Guard aircraft. The same applies regarding safety gear, like a helicopter egress device. Make sure the commander approves what the observer is wearing.

Observer Reports

Overflight report from Deepwater Horizon incident prepared 07-19-2010

This graphic is an example of what the professional or trained observer is trying to produce. Aircrews are not expected to provide overflight information at this level of detail.

During an overflight, trained observers will make notes and annotations on a map to delineate surface oil and areas of heavier oiling. To accomplish that level of detail, observers may want to go lower or slower or circle over a feature until they can get the proper notes, sketch, or photos. Later, when they return to the command post, an information manager will use that information to generate a map like the one shown here. This map is then used by the Command for decision support, oceanographers for modeling the spill, and others.

Summary

If you, the Aircrew, are the first to observe a spill and are generating the initial report, it is important to remember the critical information to report. This includes the following information:

  1. A location for the main oil patch, leading edge, and source (if available). Remember that the location should be described in two ways: latitude/longitude and distance/direction to land/landmarks.
  2. A description composed of color, structure, dimensions, and orientation. Try and use the common terminology to describe oil. Beware of false positives. If you are not sure, say so in your report. Definitely report your observation; just make sure you also report your uncertainty.

This information is the most critical to help responders understand and make decisions.

You may also find yourself transporting a trained observer to capture this and more info (for example, response assets, oceanographic features, etc.). Establish a good working relationship between the observer and aircrew. This will make your flight go much better. Remember the needs of the observer: primarily clear visibility and communications. In your pre-flight meeting, be sure to discuss mission objectives, area to cover, and flight particulars like duration, altitude, and speed.

The information in this lesson can also be found in the NOAA publication: Open Water Oil Identification Job Aid for Aerial Observation

You have now completed this lesson. Remember to take the Quiz and please answer the User Survey.