| 747 Supertanker | |
|---|---|
| The Evergreen Supertanker | |
| Type | Boeing 747-100 |
| Registration | N479EV |
| Owners and operators | Evergreen International Aviation |
| In service | 2009 - present |
The Evergreen Supertanker is a Boeing 747-100 widebody aircraft that was modified into an aerial firefighting aircraft by Evergreen International Aviation. The aircraft was originally manufactured by Boeing in 1970 for Delta Air Lines.[1] With a capacity of 20,500 US gallons (77, 600 liters), it is the largest aerial firefighting aircraft in the world.[2] The next largest firefighting tanker aircraft is the Ilyushin Il-76P. The Supertanker entered service for the first time in 2009, fighting a fire in Cuenca, Spain.[3] The tanker made its first American operation on 31 August 2009 at the Oak Glen Fire.[4][5] The current tanker is N479EV, tanker/tail number 979. (The previous plane was: N470EV, tanker/tail number 947.)
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Development started after the 2002 fire season, which saw the fatal crashes of two air tankers in the USA. The accidents, involving a Lockheed C-130A Hercules and a Consolidated PB4Y-2, prompted the U.S. Department of Interior to issue an official Request for Information on next-generation airtankers.[6]
Evergreen proposed to convert up to four of its Boeing 747-200 Freighters into massive 'Supertankers'. The first converted Boeing 747 (N470EV) made its maiden flight on February 19, 2004.[6] The current Supertanker is N479EV, a 747-100.
By June 2006, Evergreen had spent $40 million on the project and was hopeful of both FAA certification, and an evaluation contract from the US Forest Service.[7] In October 2006 the FAA issued Evergreen a supplementary type certificate for the installation and removal of internal tanks, associated systems and support structure for the aerial dispersant of liquids.[8]
An issue that impacted usage by the Forest Service was the USFS requirement for using fire retardant rather than water. When Evergreen attempted to convert the system from water dispensing to retardant, they encountered objections from the FAA. The FAA's issue related to the much greater density of fire retardant and the corresponding increased stress on the airframe thus delaying the FAA certification. The FAA determined that the Supertanker's service life would be diminished and also raised concerns about the dangers of additional stress on the airframe during firefighting operations and heavy weight maneuvering.
Unique technology is used on the Evergreen Supertanker in order to allow an aircraft as large as a 747 to carry out aerial fire fighting.
Also, because of its size, it becomes more cost effective to outfit a single plane with capabilities such as advanced GPS navigation and forward looking infrared (FLIR) capabilities, which could lead to the ability to perform nighttime operations and more accurate drops in specific areas.
The supertanker can also fly at speeds around 600 mph (970 km/h; 520 kn), allowing it to reduce response times to hot spots.
Current fire fighting aircraft use a gravity drop system. Doors in the underside of the aircraft open, allowing the contents of the tanks to discharge. This type of system requires an aircraft to fly very low, typically 200 feet (61 m) above ground level.
The Evergreen Supertanker has a pressurized system. This can disperse retardant under high pressure, for an overwhelming response, or drop retardant equivalent to the speed of falling rain. This system allows the aircraft to operate within its design criteria.[2]
Using the pressurized system, the aircraft can deliver retardant to the scene of a fire whilst flying at a height of 400 to 800 feet (120–240 m), at approximately 140 kn (260 km/h 160 mph), configured as if it were on approach for landing.
The Evergreen Supertanker’s tank system can be configured for segmented drops, allowing the contents of the tank to be released at multiple intervals while in flight.[2] According to the company, the aircraft is capable of laying down a swath of fire retardant three miles (5 km) long and as wide as an American football field.[9]
The Supertanker can operate from any airport with an 8,000-foot (2,400 m) long runway and suitable facilities. Evergreen has identified several airports across the US that meet or exceed the criteria.[2] Currently the first tanker in North America is under a CWN (call when needed) contract with Cal Fire and is stationed at McClellan Field outside of Sacramento, California.[9]
Evergreen Aviation is studying other applications for the Supertanker. Oil spill containment, chemical decontamination and weather modification are being considered. Also, regulations allow for five individuals that are not crewmembers to be carried in the upper deck. This area could be used for command and control, mapping, incident monitoring and video/communications operations.[10]
Utilizing a smaller fleet of large supertankers means potential for savings from reduced staff, maintenance, flight missions and hours flown.
On 5 December 2010, the Supertanker was deployed to Israel for fighting Mount Carmel forest fire. This undertaking goes side by side with crew and utilities donated by other international fire agencies.[11] On 9 June 2011, the Supertanker was also deployed to fight the Wallow Fire in Arizona, which was at 607 square miles (1,570 km2) burned and 0% contained at the time of deployment.[12]