USS Macon Expedition 2006
By Dr. Robert V. Schwemmer, NOAA
(With contributions from Bruce Terrell and Chris Grech; NOAA, MBARI, photos;
Published in NOON BALLOON #72)
In September 2006, a five-day archeological investigation was conducted at two major debris fields associated with the submerged wreck site of the rigid airship USS Macon, a U.S. Navy dirigible lost off California’s Big Sur coast on February 12, 1935. Principal Investigators included Bruce Terrell, Senior Archaeologist for NOAA’s National Marine Sanctuary Program (NMSP), Robert Schwemmer, West Coast Regional Maritime Heritage Program Coordinator for NMSP, Chris Grech, Deputy Director for Marine Operations at the Monterey Bay Aquarium Research Institute (MBARI), and Steve Rock, Professor of Aeronautics and Astronautics for Stanford University. Other members of the science team included an historian, educator, biologist and pilots who navigated the remotely operated vehicle (ROV).
Today the USS Macon and its associated aircraft are located within the boundaries of the Monterey Bay National Marine Sanctuary. The National Marine Sanctuary Act mandates the NMSP to manage and protect submerged archaeological resources within the sanctuaries, including those owned by the U.S. Navy. The sanctuaries are also responsible for the development of education and outreach initiatives that include maritime heritage resources.
The Monterey Bay National Marine Sanctuary’s draft Maritime Heritage Action Plan (2001) emphasizes the characterization and assessment of archaeological resources as a sanctuary priority.
The expedition was a collaborative venture involving NOAA’s National Marine Sanctuary Program, NOAA’s Office of Exploration, NOAA’s Preserve America Initiative, NOAA’s Maritime Heritage Program, Monterey Bay Aquarium Research Institute, Stanford University, University of New Hampshire, U.S. Navy, state of California, Monterey Maritime and History Museum, and Moffett Field Historical Society and Museum.
At the time of the loss USS Macon [ZRS-5; above, in 1933] was the nation’s largest and the last U.S. built rigid lighter-than-air (LTA) craft. The 784-foot Macon was completed in 1933 as part of the U.S. Navy’s LTA aviation program and championed by Navy Chief of Aeronautics Admiral William A. Moffett, who died in 1933 as a result of the USS Akron crash, sister ship to the Macon. The airship was constructed with a built-in aircraft hangar and a trapeze launch and recovery system to facilitate the Sparrowhawk biplanes. The aircraft were intended to protect the airship in war and to extend the ship’s scouting abilities. The Curtiss aircraft company adapted their diminutive F9C-2 Sparrowhawk biplane fighters to be used aboard the “flying aircraft carriers.” The planes carried arresting hooks above the top wing to capture a “trapeze bar” that would lift them into the ship. Their landing gear was removed when in operational status. This permitted the attachment of large belly-type fuel tanks that extended their range. The Macon conducted many successful launchings of the aircraft including an infamous mission to clandestinely locate President Franklin Roosevelt at sea in the Pacific aboard the cruiser USS Houston. Two of the Macon’s Sparrowhawks delivered a morning newspaper and a bag of mail to the Houston to the total surprise of the ship’s commander. Their consternation was such that it almost resulted in the court’s marshal of the Macon‘s commander. The Macon was never to be tested in battle and many have speculated that our surprise defeat at Pearl Harbor might have been avoided had Macon been on station.
[Producer’s caption: Upper keel walkway, vents and machine gun position in 1933; as it appeared on the sea floor in 2006.]
The Macon and its four Curtiss F9C-2 Sparrowhawk aircraft were lost during severe weather offshore of Point Sur on a routine flight from the Channel Islands to its home base at Moffett Field. The bow of the airship had been forced to starboard by a wind gust during a rainsquall, which caused Macon to lurch and roll. The aluminum-frame ring that supported the upper tail collapsed, puncturing three of the airship’s helium cells. Point Sur Light-Station keeper Thomas Henderson witnessed the event and recalled seeing the tail fin fly into several pieces. Orders were given to jettison the fuel and water ballast tanks in attempt to take control of the airship. At an altitude of 4,850 feet above the Pacific Ocean, the pressure release valves automatically vented helium from the cells as designed when exceeding 2,800 feet. The Macon plummeted tail first into the Pacific, floating forty minutes before foundering stern first. The accident took the lives of two of the eighty-three man crew. They were radioman First Class Ernest Dailey and mess attendant Florentino Enquiba. Today the Macon site is considered a military grave site.
[Producer’s caption: the bow mooring spindle [nicknamed ‘plumbob’] in 1933 and with its load-bearing shaft exposed on the seabed.]
Interest in locating the resting place of the Macon had been ongoing since 1988, when the first attempt to locate the Macon using side scan sonar technology proved that she was not lying at her recorded crash location. This initial effort had spawned the interests of Dick Sands of the National Museum of Naval Aviation Foundation in Pensacola, Florida as well as David Packard, founder of the Monterey Bay Aquarium Research Institute. They asked Chris Grech, a ROV pilot for MBARI, who participated in the search for the Macon in 1988, to head up another expedition to investigate several recorded sonar anomalies from the 1988 trip.
[Producer’s photo of Chris at the 1991 NAA Reunion, Pensacola FL.]
A section of airship girder that had been snagged in commercial fisherman Dave Canepa’s trawl net was on display in a Moss Landing seafood restaurant. It was unrecognized until noticed by Marie Wiley Ross, daughter of Macon‘s commander Herbert V. Wiley who recognized it for what it was, having seen such girders in her childhood. Grech and Sands were able to trace the object back to Canepa and learn of the wreck’s location. In June 1990 Grech coordinated with the U.S. Navy’s three-man deep submergence vehicle (DSV) Sea Cliff, to locate and document the Macon’s remains at a depth of 1500 feet. MBARI returned to the site in February 1991 and videotaped the site using a ROV. The team located debris fields that included girders, gasoline tanks, the nose-mounted mooring assembly and the dirigible’s German-made Maybach engines.
MBARI was able to record windows, chairs, and chart tables, though flattened. The four Curtiss F9C-2 Sparrowhawk hook-on airplanes were also located revealing their aluminum frames along with deteriorated wing fabric still intact. The 1990/91 surveys recorded the bow and mid-section debris fields. During these survey missions MBARI worked with the Navy to collect artifacts which included one of the arrester hooks lying on the sea floor next to a Sparrowhawk. This artifact was conserved at East Carolina University. At least two interviews have been documented with witnesses or their relatives tangential to the Macon and its Sparrowhawk aircraft. An interview was conducted with Gordon Wiley, son of Lt. Comdr. Herbert V. Wiley, master in command of the Macon at the time of its loss.
[Producer’s caption: Two styles of lightweight chairs were aboard, as seen in the radio room in 1933 with one seen on the sea floor in 2006. HD video shows the knobs still on the equipment.]
An additional series of interviews were conducted in 1995 with the late ret. USN Chief Lew “Woody” Williamson of Richmond, Virginia who flew in a “utility” squadron at Norfolk, Virginia in the 1930s and wrote performance manuals for aircraft. Williamson tested a Curtiss F9C-2 Sparrowhawk that was not on the Macon at the time of its crash. His interest in the craft led him to communicate at length with ret. Admiral Harold Blaine “Min” Miller who, as a Lieutenant, commanded the Sparrowhawk squadron on the Macon and who survived the crash.
USS Macon Expedition 2006
The remains of the Macon’s assemblage provide an opportunity to study the relatively undisturbed archaeological remnants of a unique period of aviation history. These remains are a significant resource both for the U.S. Navy and the Monterey Bay National Marine Sanctuary. Dirigibles were an important development in the history of aviation. There are no other known examples of these craft that can be studied. While there is one known example of a Sparrowhawk in existence, it is a composite airplane built from the parts of the last two surviving F9C-2s. Future aviation historians and the public will benefit from the comprehensive documentation and management of these craft.
In preparation for the expeditions regional museums and historical societies have also contributed towards the research effort, providing historic imagery and primary source documentation. The Monterey Maritime and History Museum, which has an exhibit on the Macon, has assisted with research. The Moffett Field Historical Society, which is associated with interpreting the Macon’s hangar in Sunnyvale, California, was also involved in early project planning.
The project was designed in two phases, Phase I recommended an updated survey of the debris field areas using state-of-art side-scan sonar to determine the extent of the wreckage. A side-scan-sonar survey of the site was successfully conducted by the sanctuary in collaboration with the U.S. Geological Survey, MBARI and Moss Landing Marine Laboratories on May 1-3, 2005 aboard the NOAA R/V McArthur II.
The Phase II 2006 expedition encompassed several objectives. The technical component involved video and photo documentation of the physical remains of the airship and four aircraft utilizing a ROV tethered to MBARI’s R/V Western Flyer, a 117-foot (35.66 meter) SWATH oceanographic ship with a small waterplane-area twin hull. [Below.] The vessel provides a stable platform for deploying, operating, and recovering the tethered ROV Tiburon and capable of working at the required depth of the Macon site. Tiburon has a maximum working depth of 13,123 feet (4000 meters). With a 30 meter/minute descent rate the ROV was quickly deployed six times to the Macon’s two debris fields over the course of the five day mission.
[Producer’s caption: gas pressure relief valves, about a yard across, before cell insertion and now littering the sea floor.]
Underwater navigation of the ROV is achieved through a Sonardyne USBL navigation system which produces nearly 1 meter accuracy at the depths of the Macon site. This position data is logged on the vessel, and coordinated with other data sources such as sub-sea environment data, ship’s position, Greenwich Mean Time (GMT), video time code, camera positions, etc.. The ROV also incorporates a Doppler Velocity Log (DVL) system for tracking and station keeping controls of the ROV, in addition to basic Auto heading and Auto Depth controls.
[Producer’s Caption: At sea aboard the Pacific Flyer, Grech (left) and Schwemmer on top of the ROV Trburon; below, on folding deck, at 3rd from right, Terrell, standing beside Doughty, in white T-shirt. Producer in NAA cap holding spotlamp.]
ROV Tiburon incorporated the newly developed Stanford University control software, which utilizes a real time HDTV low resolution feed to build a computer based video-mosaic. This system provided close-loop control of the ROV using the vision (HDTV camera) and/or DVL device which enabled the computer to control the ROV. The Stanford control system can receive position data from both devices (DVL and HDTV) along with existing auto altimeter functions to control the ROV path. This allows the ROV pilots to see and build an accumulative mosaic image by the overlap of video tiles, which provides strategic tools in completing the mosaic survey. The pilot can control image overlap, distance, station keeping, and velocity can all be driven by computer commands via the pilots. The photo-mosaic will provide for the first time a comprehensive site map showing the distribution of artifacts on the surface of the two debris fields.
An outreach component included the hosting of a live web uplink from Tiburon during the operations to educate students and the community about the deepwater technology used to conduct an archaeological survey. Noah Doughty, an educator from Mission College Preparatory High School in San Luis Obispo, California served as the teacher-at-sea and provided daily mission updates posted to the internet.
The primary goal of the mission was to conduct a comprehensive survey of the wreck site of the USS Macon and four aircraft that can be used to evaluate the archaeological context of the craft’s remains. This will allow NOAA/NMSP and the U.S. Navy Historical Center to determine the condition of the site, the level of preservation of the archaeological remains and the potential for future research at the site. It also provided an opportunity to identify the remaining elements of the aircraft.
[Producer’s caption: Exposed to the crushing pressure at the Macon grave depth, a polystyrene cup is reduced to shot-glass size, making a conversation-piece souvenir for the participants.]
During the 2006 expedition, more than 40 hours of deepwater surveys were completed utilizing the ROV Tiburon. The surveys recorded the visual wreckage through high-definition videotape and still imagery that will be used to create a photo-mosaic of the two debris fields. One dive included verifying whether 2005 side-scan sonar targets were newly discovered debris fields or geologic features. No new debris fields were discovered, but two additional fuel tanks were located during transit of this exploration phase.
The two major debris fields, designated A and B, measure 60 meters (197 feet) in diameter and are elevated several meters above the seafloor. The fields are separated by a distance of 250 meters (820 feet) and show an accumulation of several centimeters of sediment since initial surveys conducted in 1990. Scientists have concluded that sections of the aluminum girder show signs of degradation after 71 years in the marine environment.
Some of the distinguishable features in Debris Field A include the airship’s hangar bay containing four Sparrowhawk biplanes; two were identified by individual color striping on their wings (bureau numbers 9058 & 9061). The wing fabric of the other two Sparrowhawks was too deteriorated to provide identifiable color features. Other visible features on the Sparrowhawks included the telescopic gun sites, skyhooks, detached landing gear, floatation bags, and one engine was exposed with propeller still attached. The wings in most cases showed exposed spars, ribs, ailerons, but one of the biplane’s wing fabric had a partial U.S. star with the red, while and blue color pattern clearly visible.
[Producer’s caption: NASM’s restored #9056 and the remains of #9058.]
Read on to USS Macon: Respects Paid 2006 Part Two
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