The National Natural Landmarks Program recognizes and encourages the conservation of outstanding examples of the natural history of the United States. It is the only national natural areas program that identifies and recognizes the best examples of biological and geological features in both public and private ownership; the program was established on May 18, 1962, by United States Secretary of the Interior Stewart Udall. The program aims to encourage and support voluntary preservation of sites that illustrate the geological and ecological history of the United States, it hopes to strengthen the public's appreciation of the country's natural heritage. As of November 2016, 599 sites have been added to the National Registry of National Landmarks; the registry includes nationally significant geological and ecological features in 48 states, American Samoa, Puerto Rico, the U. S. Virgin Islands; the National Park Service administers the NNL Program and if requested, assists NNL owners and managers with the conservation of these important sites.

Land acquisition by the federal government is not a goal of this program. National Natural Landmarks are nationally significant sites owned by a variety of land stewards, their participation in this federal program is voluntary; the legislative authority for the National Natural Landmarks Program stems from the Historic Sites Act of August 21, 1935. The NNL Program does not have the protection features of Section 106 of the National Historic Preservation Act of 1966. Thus, designation of a National Natural Landmark presently constitutes only an agreement with the owner to preserve, insofar as possible, the significant natural values of the site or area. Administration and preservation of National Natural Landmarks is the owner's responsibility. Either party may terminate the agreement; the NNL designation is made by the Secretary of the Interior after in-depth scientific study of a potential site. All new designations must have owner concurrence; the selection process is rigorous: to be considered for NNL status, a site must be one of the best examples of a natural region's characteristic biotic or geologic features.

Since establishment of the NNL program, a multi-step process has been used to designate a site for NNL status. Since 1970, the following steps have constituted the process. A natural area inventory of a natural region is completed to identify the most promising sites. After landowners are notified that the site is being considered for NNL status, a detailed onsite evaluation is conducted by scientists other than those who conducted the inventory; the evaluation report is peer reviewed by other experts to assure its soundness. The report is reviewed further by National Park Service staff; the site is reviewed by the Secretary of the Interior's National Park Advisory Board to determine that the site qualifies as an NNL. The findings are provided to the Secretary of the Interior who declines. Landowners are notified a third time informing them that the site has been designated an NNL. Prospective sites for NNL designation are aquatic ecosystems; each major natural history "theme" can be further subdivided into various sub-themes.

For example, sub-themes suggested in 1972 for the overall theme "Lakes and ponds" included large deep lakes, large shallow lakes, lakes of complex shape, crater lakes, kettle lake and potholes, oxbow lakes, dune lakes, sphagnum-bog lakes, lakes fed by thermal streams, tundra lakes and ponds and marshy areas, sinkhole lakes, unusually productive lakes, lakes of high productivity and high clarity. The NNL program does not require designated properties to be owned by public entities. Lands under all forms of ownership or administration have been designated—federal, local and private. Federal lands with NNLs include those administered by the National Park Service, National Forest Service, Bureau of Land Management, Bureau of Reclamation and Wildlife Service, Air Force, Marine Corps, Army Corps of Engineers and others; some NNL have been designated on lands held by Native tribes. NNLs have been designated on state lands that cover a variety of types and management, as forest, game refuge, recreation area, preserve.

Private lands with NNLs include those owned by universities, scientific societies, conservation organizations, land trusts, commercial interests, private individuals. 52% of NNLs are administered by public agencies, more than 30% are privately owned, the remaining 18% are owned or administered by a mixture of public agencies and private owners. Participation in the NNL Program carries no requirements regarding public access; the NNL registry includes many sites of national significance that are open for public tours, but others are not. Since many NNLs are located on federal and state property, permission to visit is unnecessary; some private property may be open to public visitation or just require permission from the site manager. On the other hand, some NNL private landowners desire no visitors whatever and might prosecute trespassers; the reasons for this viewpoint vary: potential property damage or liability, fragile or dangerous resources, desire for solitude or no publicity. NNL designation is an agreement between the federal government.

NNL designation does not change ownership of the property nor induce any encumbrances on the property. NNL status does not transfer with changes in ownership. Participation in the NNL Program involve

The 52d Expeditionary Flying Training Squadron is part of the Iraq Training and Advisory Mission - Air Force and is based at Camp Speicher, Iraq. It operates Beechcraft T-6A Texan II aircraft conducting flight training for members of the Iraqi Air Force, it was tasked to train and advise Iraqi Airmen in order to build the institutional capacity to conduct credible fixed and rotary wing flight training for the Iraqi Air Force. In late 2011, all U. S. forces were withdrawn from Iraq and the squadron was inactivated. The squadron was first activated at Langley Field, Virginia, as the 52d Bombardment Squadron in January 1940, one of the original squadrons of the 29th Bombardment Group, its organization was part of the pre-World War II buildup of the United States Army Air Corps after the breakout of war in Europe. In May, it moved to MacDill Field, where it was equipped with a mix of pre-production YB-17s and early model Boeing B-17 Flying Fortresses and Douglas B-18 Bolos; the squadron was still at MacDill when the Japanese attacked Pearl Harbor, it began to fly antisubmarine patrol missions in the Gulf of Mexico from January 1942.

By the summer of 1942, the U-boat threat in the Gulf began to diminish, with all German submarines being withdrawn from the area by September. No longer needed in the Gulf, the squadron moved to Gowen Field, where it became an Operational Training Unit; the OTU program involved the use of an oversized parent unit to provide cadres to "satellite groups". The 96th, 381st, 384th and 388th Bombardment Groups were all formed at Gowen in the second half of 1942. In 1943, the squadron exchanged its B-17s for Consolidated B-24 Liberators; the squadron mission changed as the Army Air Forces' need for new units diminished and its need for replacements increased. The squadron became a Replacement Training Unit. Like OTUs, RTUs were oversized units. However, standard military units, like the 52d Squadron, were based on inflexible tables of organization, were not proving well adapted to the training mission. Accordingly, a more functional system was adopted in which each base was organized into a separate numbered unit.

The 29th Bombardment Group and its squadrons were inactivated. Its personnel and equipment, along with that of supporting units at Gowen Field were combined into the 212th AAF Base Unit on 1 April 1944; the AAF was organizing new Boeing B-29 Superfortress heavy bombardment units, the squadron was activated the same day at Pratt Army Air Field, Kansas. It returned to flying B-17s until B-29s became available for training, it continued training with the Superfortress until December 1944. Training included long range overwater flights to Puerto Rico, it deployed to North Field, where it became a component of the 314th Bombardment Wing of XXI Bomber Command. Its first combat mission was an attack of Tokyo on 25 February 1945; until March 1945, it engaged in daytime high altitude attacks on strategic targets, such as refineries and factories. The campaign against Japan switched that month and the squadron began to conduct low altitude night raids, using incendiaries against area targets; the squadron received a Distinguished Unit Citation for a 31 March attack against an airfield at Omura, Japan.

The squadron earned a second DUC in June for an attack on an industrial area of Shizuoka Prefecture, which included an aircraft factory operated by Mitsubishi and the Chigusa Arsenal. Staff Sergeant Henry E."Red" Erwin of the squadron was awarded the Medal of Honor for action that saved his B-29 during a mission over Koriyama, Japan, on 12 April 1945. Sgt Erwin was assigned to job of dropping white phosphorus bombs through a launching chute in the floor of his bomber. A bomb exploded in the chute and shot back into the plane wounding Sgt Erwin and filling the plane with heavy smoke. Despite being blinded by the burning bomb, he picked it up, carried it forward to the cockpit area of the plane and threw it out an open window. Once the smoke had cleared, the pilot was able to pull the Superfortress out of a dive and recover at an emergency base. During Operation Iceberg, the invasion of Okinawa, the squadron was diverted from the strategic campaign against Japanese industry and attacked airfields from which kamikaze attacks were being launched against the landing force.

Following VJ Day, the squadron dropped food and supplies to Allied prisoners of war and participated in several show of force missions over Japan. It conducted reconnaissance flights over Japanese cities; the squadron remained on Guam until it was inactivated in March 1946. It conducted undergraduate pilot training from 1972–1977 and 1990-1997; the 52d was reactivated in March 2007 as the first US Air Force expeditionary flying training squadron and the first flying training squadron activated in a combat zone. Its mission is to train and advice Iraqi airmen to conduct undergraduate and instructor pilot training for the Iraqi Air Force. Constituted as the 52d Bombardment Squadron on 22 December 1939Activated on 1 February 1940 Redesignated 52d Bombardment Squadron, Very Heavy on 28 March 1944 Inactivated on 1 April 1944Activated on 1 April 1944Inactivated on 20 May 1946Redesignated 52d Flying Training Squadron on 22 March 1972Activated on 1 July 1972 Inactivated on 30 September 1977Activated on 11 May 1990Inactivated on 1 April 1997Redesignated 52d Expeditionary Flying Training Squadron and converted to provisional status on 23 March 2007Activated on 29 March 2007 29th Bombardment Group, 1 February 1940 – 1 April 1944 29th Bombardment Group, 1 April 1944 – 20 May 1946 29th Flying Training Wing, 1 July 1972 – 30 September 1

The 7-inch unrotated projectile, or UP, was a short-range anti-aircraft rocket developed for the Royal Navy. It was used extensively by British ships during the early days of the Second World War, but proved unreliable and ineffective in operation, prompting the withdrawal of the system during 1941; the name "unrotated projectile" was a cover name to disguise the use of a rocket system, comes from the fact that the projectile was not spin-stabilized. The weapon fired ten at a time. A small cordite charge was used to ignite a rocket motor which propelled the fin-stabilized 7-inch-diameter rocket out of the tube to a distance of about 1,000 feet, where it exploded and released an 8.4-ounce mine attached to three parachutes by 400 feet of wire. The idea was that an aeroplane hitting the wire would draw the mine towards itself, where it would detonate; the UP was developed by Sir Alwyn Crow, the director of the Projectile Development Establishment at Fort Halstead. In November 1939, Winston Churchill as First Lord of the Admiralty asked Crow to produce urgently a means of laying an aerial minefield and to consider other methods of protecting ships against aircraft.

It is that Churchill was influenced in his request by his friend and advisor, Frederick Lindemann, who had advocated a scheme for "dropping bombs hanging by wires in the path of attacking aircraft". A high-altitude barrage was developed: an aerial minefield up to 19,000 feet, the fast aerial mine up to 2,000 feet, the PE fuse up to 18,000 feet and the UP up to 20,000 feet; the 7-inch UP was developed with the 2-inch and 3-inch UP systems, the latter being deployed in the anti-aircraft Z Batteries which were operated by the Home Guard and was the basis of the RP-3 air-to-surface rocket and the Mattress surface-to-surface multiple rocket launcher. The weapon was not effective as it was slow to load and aircraft could avoid the wires, it was replaced in the war by the 2-pounder or Bofors 40 mm gun. A demonstration of the weapon for Churchill on Admiral Jack Tovey's flagship at Scapa Flow exposed a flaw in the concept. Practice bombs were fired, when there was an unexpected change of wind, they drifted back onto the ship and some became entangled in the rigging and superstructure.

The dummy rounds caused little or no damage, but Tovey was amused at the embarrassment thus caused to the weapon's advocates and Churchill. The UP ammunition aboard HMS Hood was seen to be on fire just before she exploded and sank in May 1941; the report of the Admiralty Board of Enquiry into the sinking of Hood in September 1941 concluded "That the fire, seen on Hood's boat deck, in which UP and/or 4-inch ammunition was involved, was not the cause of her loss", but it noted that "Action has been taken to land UP mountings and ammunition" in the rest of the fleet. Rocket length: 32 inches Rocket weight: 35 pounds Horizontal range: 3,000 feet Sinking speed of mine: 16 to 23 feet per second. Mounting weight: 4 tonnes. AA mine discharger - a Japanese anti-aircraft mortar. Henschel Hs 297 / 7.3 cm Föhn-Gerät - a German anti-aircraft rocket launcher. Holman Projector - a steam-powered anti-aircraft grenade launcher. Z battery British 3-inch land-based anti-aircraft rocket launcher Furneaux-Smith, F..

The Professor and the Prime Minister: The Official Life of Professor F. A. Lindemann Viscount Cherwell. Boston: Houghton Mifflin Company. BBC: Memories of the Home Guard Tony DiGiulian, British UP AA Rocket Mark I HMS Hood Anti-Aircraft Armament Schermuly and his rockets British UP AA Rocket Mark I