Firefighting air tankers, the early years

World first crop dusting experiment
World first crop dusting experiment (August 3rd 1921, Troy, Ohio) using an aircraft – Left: McCook Field engineer Etienne Dormoy (left) who designed the hopper and operated it during the flight ; Right: Lieut. J.A. Macready who piloted the plane (Curtiss JN-6). Photo: Houser, J. S. “The Airplane in Catalpa Sphinx Control.” Ohio Agricultural Experiment Station, Monthly Bulletin 7 (1922)

By Richard L. Hilderbrand

Military aircraft have long been used to apply insecticides and herbicides.  An entomologist from Cleveland, C. R. Neillie, believing that airplanes could be used to dust a stand of trees, worked with the Army Air Service at McCook Field in Dayton to test the idea.  On August 3, 1921, Lt. John A. Macready assisted in the successful treatment of catalpa trees using insecticide dropped from a Curtiss JN-6 airplane to kill sphinx caterpillars.

first crop dusting experiment
World’s first crop dusting experiment, Aug. 3, 1921

In 1933 a study summarized the military use of chemicals dispersed by aircraft and included the possibility of using chemicals to deny the opposition the use of rear areas and lines of communication.  This basic idea was applied in Vietnam to deny cover and limit food crops.

An engineering study completed in 1952 laid the groundwork for the development of the MC-I “Hourglass” system which was first used for defoliation in Vietnam.  Built by the Hayes Aircraft Corporation of Birmingham, AL, the MC-1 system included a 1,000-gallon tank and equipment to support six spray nozzles.

The MC-1 was used on many occasions but was not satisfactory to spray jungle foliage in Vietnam in “Operation Ranch Hand” due to the requirement for two passes over the treatment area.  Knowing a second pass was coming for adequate treatment allowed the enemy on the ground to prepare a “return” welcome party.  On February 2, 1962, Ranch Hand lost an aircraft and the crew became the first Air Force fatalities in Vietnam.

The need for a three gallon/acre spray capability in one pass resulted in the development in 1966 of the A/A45Y-1 sprayer which incorporated spray booms under each wing and under the tail and a larger pump to increase pressure from 38 to 60 psi.  The A/A45Y-1 Internal Defoliant Dispenser, also designed and manufactured by Hayes, was a complete dispensing system with a 1000 gallon tank, jettison capability, and rapid installation into and from a C-123.

In the spring of 1953, Douglas Aircraft Company was flying a DC-7 prototype out of Palm Springs Airport using water in a tank as a ballast to represent a load. At the end of flight-testing, the four-engine DC-7 made a low pass over the Palm Springs runway and dumped its ballast through three six-inch valves in the airplane’s belly. The result was a wide, mile-long swath of water that caught the attention of the DC-7’s pilots as well as observers, thus starting the concept of aerial attack on fires. The first application of aerial attack adapted a 1939 Stearman biplane that had been converted into a cropduster. In 1955 Willows Flying Service, a California agriculture chemical applicator, cut a hole in the airplane’s belly fabric and fitted the chemicals hopper with a flapper hatch that opened when the pilot pulled a rope to release 170 gallons of water. In August of that year the Willows Stearman made several runs on a fire burning in Mendocino National Forest, dropping 170 gallons on each run and assisting in “knocking down hotspots.” This was the first time that a real forest fire had been attacked using water dropped from the air.

TBM air tanker
TBM air tanker being refueled by truck in 1966 in the Beaverhead National Forest, Montana. The TBM payload was 800 gallons of retardant. Photograph provided by Mr. Dave Stack courtesy of National Museum of Forest Service History, Missoula, Montana.

In 1958 a single engine TBM Avenger (Grumman TBF manufactured by General Motors) dropped retardant on a fire at Lake Elsinore, California and started the use of the TBM as a retardant tanker. Continuing through the 1960s, the tankers were usually modifications of WWII bombers, such as the TBM, that carried a several hundred gallons of retardant and dropped the load using the bomb bay. These drops were bulk drops and frequently a mass of retardant would break the trunks of trees. The military bombers were designed to withstand the “negative g” wing-loads of rapid cargo (e.g., bombs) deployment but were not necessarily adapted to the low-level drops in mountain terrain. Other aircraft used were the PB4Y, B-26, B-17, and P2V Neptune. Other military aircraft were used such as the Grumman AF with a payload of 800 gallons and the C-123. They were usually single purpose aircraft owned and operated by private contractors with much time parked on the ramp. These early pilots flew on the edge and would occasionally return to the retardant base with pieces of tree-top in their wings. C-119 “Flying Boxcars” were used through about 1987 and a few even had 3,400-pound-thrust Westinghouse J34 turbojet atop the fuselage.

One story from 1979 and recounted by Bill Waldman (Aero Union pilot) concerned a drop he made east of the Colorado River in the Grand Canyon area. He made a partial drop and was pulling up out of the canyon. The C-119 made a drastic roll to the right so the co-pilot was looking at the rocks on the hill through an overhead window. Waldman jettisoned the load, corrected the roll and looked for an emergency landing spot and realized the Ford proving ground south of Kingman, AZ, was the best available. He held the plane level long enough to reach the skidpad test area at the proving ground, clearing the many new Fords on the pad by a few feet. He landed and was met by the manager of the proving ground who told his machine shop staff to give this pilot and plane anything they need to “get off my skidpad.” A 4 x 6 inch piece of aluminum and sheet metal screws repaired the flap and the plane with one dead cylinder due to a swallowed exhaust valve and a make-do patch flew to the canyon airfield for repairs. Over the time of their use three C-119s were lost due to structural failure.
Following the WWII bombers, the DC-4 (C-54), DC-6, DC-7, MD-87 and Lockheed P-3 Orion have been employed. California fire fighting continues use of military aircraft with the Grumman S-2T tanker that can hold about 1,200 gallons of retardant. The S-2T aircraft were used to track submarines until the 1970s.

Global Supertanker 747
Global Supertanker 747 approaching directly toward photographer Steven Whitby. Photo used by permission of Steven Whitby Photography.

The use of aerial firefighting aircraft has reached a new peak with the conversion of DC-10 and Boeing 747 aircraft to supertankers capable of carrying thousands of gallons of retardant. The supertankers drop at a few hundred feet or higher at 140 knots but cannot fly at tree top level as did the early pilots. The DC-10 conversions carry a load of 9,400 gallons and the 747 carries 17,500 gallons. The 747 interior contains several tanks that cover much of the length of the interior including the compressed air tanks for dispersal. The volume of retardant dropped is impressive and dispersal improved – the 747 may make a drop covering two to three miles and 100 yards wide.

Water can be used to cool a fire; however, the retardant is usually distributed in a line in front of the fire to assist ground teams with building a line to stop the fire. The retardant is a mixture of fertilizer type material that retains or absorbs moisture, decreases fire intensity and slows advance of the fire (even after drying) and is intended to act as a fire break when the fire reaches the retardant drop line. In 1956 borate was briefly tested on fires in southern California and found to be a soil sterilant but early air tankers were often called “borate bombers.” Today’s retardant is generally an ammonium-phosphate or sulfate based commercial mixture which is colored red to mark the drop site and weighs about nine lbs/gallon. The Monsanto brand Phos-Check became available in 1962. The product PHOS-CHEK® is now trademarked and produced by Perimeter Solutions and is one of a several retardant products. Certain current formulations of retardants can be used to pretreat fuel to act as a retardant and are resistant to weather conditions for extended time periods.

Air Tanker 855 drops Indian Canyon Fire
Air Tanker 855 drops on the Indian Canyon Fire in the Black Hills of South Dakota at 8:27 p.m. MDT July 16, 2016. Photo by Bill Gabbert.

Jim Hickman has memories of a few incidents from the early development of Modular Aerial Firefighting System (MAFFS) air tankers. When mixed with water, retardant is not only wet but very sticky and slick when coating a surface. In an early trial several hundred gallons of the retardant were loaded into the modules of a C-130 and the test run started. When valves were opened there was a dramatic and immediate dispersal with much of the sticky retardant mist flying back through the open ramp into the interior of the aircraft, where it coated every surface. Fortunately, it did not access the cockpit. Several modifications were completed to improve the filling of the tanks and the placement of dump nozzles to achieve proper dispersal of the retardant.

There were other errors and incidents which occurred with civilian-operated aircraft. One tanker had dual wheels on each main gear and had loaded at the tanker base at Prescott, AZ. The plane taxied out of the retardant pit, turned onto the main runway and took off. In about a minute the dispatcher had a frantic call from a civilian telling them that a huge wheel had just fallen off an airplane, hit on the street, bounced over a house, and was off in the woods. About then a pickup roared up to the tower and one of the retardant crewmen ran in with a handful of debris from the tarmac where the tanker had turned to go onto the main runway. The lead plane pilot watched while the tanker pilot lowered the main gear. Sure enough, the outside dual on one main landing gear was missing. The plane went on to the fire and dropped retardant, diverted back to the home base and made a safe landing. During development, the military pilots had flying experience but no fire suppression experience. In early MAFFS operations the military pilots were having trouble dropping the retardant in the location needed at the fire. As orientation the USAF pilots were flown in civilian tankers with experienced tanker pilots. Upon return from an orientation flight in a B-17 the AF pilot was asked what he thought – his reply, “The SOB was trying to kill me.”

A recent tragedy was the loss of Coulson Aviation’s Tanker 134 (a former Navy C-130) fighting Australia’s bush fires on January 23, 2020. The tanker was outfitted with Coulson’s RADS XXL retardant delivery system capable of dropping 4000 gallons on each run. The three crew members lost were decorated veterans of the U.S. Military services and each had extensive experience. The crash occurred north of the Cooma-Snowy Mountains Airport (near Peak View), New South Wales.

One incident of interest to me concerned a PB4Y2 on a fire in Alaska. I was on the fireline and watched with concern as the pilot came in on the level approaching below a fire but needing to climb up to the fire on the side of a mountain. Normal procedure was to come loaded over a ridge or hilltop and drop retardant going down the slope and then pulling up after the drop and returning to base. The drop was made, the engines roared and the PB4Y2 just cleared the trees on the top of the ridge. The PB4Y2 crashed a few days later July 22, 1968, on Joaquin Mountain in Alaska with the loss of four lives.

In another case a contract C-130A (civilian-operated) aircraft was flying against the Cannon Fire, near Walker, CA, on June 17, 2002, when it experienced a structural failure of the center wing section, causing both wings to fold upward and separate from the aircraft. Two weeks later another contract-operated PB4Y from WWII crashed near Estes Park, CO, also as a result of structural failure. A total of five personnel were killed in the two crashes.

As a result of the accident investigations, on May 10, 2004, the USFS abruptly terminated the contracts for many of the large tankers over safety concerns. The decision affected tanker contracts issued by both the USFS and Bureau of Land Management. In the vacuum left by the absence of the large tankers, the Forest Service said it would shift its firefighting strategies to rely more on heavy helicopters, light tankers and military MAFFS. With improvement of safety procedures the strategy has changed and the large aircraft, including supertankers, are currently operating world-wide.

The article was edited to show that the TBM was manufactured by General Motors, not Ford.

Richard Hilderbrand, Ph.D., was a Smokejumper in the mid 1960’s and is a Life Member of the National Smokejumper Association.  He was on fires in the Northwest US and Alaska.  He has personally seen TBM aircraft return with tops of trees in their wings and has seen retardant drops from many aircraft.  He has jumped from a Ford Tri-motor, DC-2, DC-3, Twin Beech, Grumman Goose and other jump aircraft.   Special thanks are due to Jim Hickman, Bill Ruskin, Bill Allred, Bill Waldman, Bill Gabbert, and Steve Whitby for their contributions and review! In addition, I thank the many websites referenced in the text for their information; however, any errors are the responsibility of the author.

Air tankers in Tucson’s Pima Air & Space Museum

Grumman AF-2S
Grumman AF-2S in the Pima Air Museum. Photo by Steve Stenkamp.

Steve Stenkamp sent us these photos he took at the Pima Air & Space Museum last March. “It’s an excellent way to spend 3-4 hours,” he said.

Thanks Steve!

C-123 in the Pima Air Museum. Photo by Steve Stenkamp.
P2V-7 in the Pima Air Museum. Photo by Steve Stenkamp.
DC-7B in the Pima Air Museum. Photo by Steve Stenkamp.
C-119C in the Pima Air Museum. Photo by Steve Stenkamp.

Over 400 historic aircraft are on display at the museum that encompasses 80 acres of exhibits.

We grabbed this photo of the museum from Google Earth:

Pima Air and Space Museum
Pima Air and Space Museum. Google Earth, August 18, 2018.

If you go:

Location: 6000 E Valencia Rd, Tucson, AZ 85756
Tickets: $10 to $16

It is just south of Davis-Monthan AFB AMARG Facility and the military aircraft “boneyard” with over 4,400 planes in storage. From the Pima Museum you can board a bus to tour the boneyard but you have to apply for a security clearance at least 10 business days in advance of the desired tour date. You can apply for the clearance up to 90 days in advance.

MAFFS — A look back

Development and use of the Modular Airborne Firefighting System

By Richard L. Hilderbrand

MAFFS loading
Members of the 302nd Airlift Wing load a U.S. Forest Service Modular Airborne Firefighting System (MAFFS II) unit into a C-130 Hercules aircraft April 23, 2020 at Peterson Air Force Base, Colo. The MAFFS unit is used during annual aerial firefighting training requirements. (U.S. Air Force photo by Staff Sgt. Justin Norton)

The Modular Airborne Firefighting System (MAFFS) program is a joint effort between the US Forest Service and Department of Defense (DoD).  The USFS owns the MAFFS equipment and supplies the retardant, while the Department of Defense has provided the C-130 aircraft, pilots, maintenance, and support personnel to fly the missions since the 1970s.

The current MAFFS II is configured for deployment using the C-130 aircraft, with installation requiring less than an hour.  The system carries up to 3,000 gallons of water or retardant which can be discharged using 1,200 PSI air pressure in a matter of seconds.  The system can provide a fire line 60 or more feet wide and about a quarter mile long.

The USFS had used bulk retardant drops from older aircraft; however, improved dispersal systems did not exist and the USFS had a continuing need to provide assistance to ground personnel on a fire, especially for initial attack.  At the same time, the A/A45Y-1 spray equipment was in use in Vietnam during Operation Ranch Hand.  In April 1970, the DoD suspended the use of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) herbicide, due to the presence of the toxic contaminant dioxin in the defoliant. In addition, in 1973 the Paris Peace Accord ended direct U.S. involvement in Vietnam.  These events left military spray equipment looking for a mission.

The search for a mission led to a proposal by FMC (previously Food Machinery and Chemical Corporation) that the DoD spray equipment be modified for use by the USFS to drop retardant in wildfire suppression.  In 1971 Arnold Adams (equipment development specialist for FMC) met with Jim Hickman (USFS, Washington Office, Division of Aviation and Fire Management) as staff liaison for equipment development.  Numerous meetings and review of the existing spray equipment at FMC in San Jose, CA, followed to determine applicability to wildfire use.  With positive initial evaluation by Hickman and Adams, the proposal was elevated through USFS, Department of Agriculture, USAF, and DoD.  A meeting of senior officials was held at the Pentagon for a complete review and the program was given final and unanimous approval by the Departments.

Following the initial proposal and production of the first MAFFS unit by FMC, the USFS turned to Aero Union Corp. for the manufacture of the operational MAFFS.  On October 17, 1972, Dale Newton of Aero Union Corporation of Chico, CA, was awarded patent 3,698,480 on the basic MAFFS type system.  This included the method and apparatus for retardant use from a large capacity main slurry storage coupled by means of fluid transfer pipes to a lower capacity slurry dispensing tank positioned aft of the main tank in the doorway of the aircraft’s cargo doors.  This patent envisioned a plane such as the C-130 for operation and using engine operation to provide compressed air to disperse retardant.

Bill Waldman of Aero Union provided the description of the development of the MAFFS to the current configuration.  The original MAFFS was in four components to be loaded individually with filling and pressurization being completed on the ground.  The compressor was driven by a VW engine and took many minutes of ground time to charge.  Support bases were selected, equipment gathered, and pilot training on operational procedures of wildfire suppression was conducted. USFS pilots, several of whom were ex-military, and contractor pilots were utilized.  Much of the training was done at the USFS National Training center at Marana, AZ.  The MAFFS era had begun!

An improvement of equipment by Aero Union led to a diesel engine for air compression and a trailer with all four components to be loaded as a single unit to the C-130.  Due to air and retardant characteristics the original design created more of a mist than a liquid dispersion that exited directly out of the aft ramp.  Major modifications were needed to achieve the dispersal of the dense retardant as a liquid by pressurized air with nozzles exiting the ramp and pointing downward from the aft ramp of the C-130.  Aero Union designed and produced the MAFFS II which is in current use.  Nine units were produced with two assigned to each MAFFS-capable military unit and one spare, of which one was lost in the crash of MAFFS #7.  MAFFS II was designed with one discharge nozzle exiting the aircraft from the left jump door, full capability to charge the system in the air, and a capacity of 3000 gallons.  In addition, the trailer system was improved to allow rapid loading and unloading of the C-130.

Aero Union also developed a version of a retardant tank known as the Retardant Aerial Delivery System (RADS).  Coulson Aviation purchased the intellectual property rights to RADS-1 in 2012 and has improved the RADS system, making several versions including the 4,000-gallon RADS-XXL and claim a 1600 gallon/second dispersal rate and reduced equipment weights.

A private company, United Aeronautical Corporation (UAC) headquartered in North Hollywood, California, bought P-3 aircraft from Comerica Bank which acquired Aero Union’s assets following the company’s financial problems. UAC then partnered with Blue Aerospace to market the P-3s.  Steve Benz, the Blue Aerospace Vice President for Business Development, said UAC and Blue Aerospace now have the Aero Union intellectual property for both generations of the MAFFS and the second-generation RADS, RADS2, a gravity assisted, constant-flow retardant tank system which has been successfully used in air tankers.  To handle the MAFFS and RADS2 business, the two companies formed an organization named MAFFS Corp. They provide parts and service for existing MAFFS units, and are manufacturing new MAFFS II systems.  (For more information on the MAFFS II see Ten things to know about MAFFS military air tankers.)

An unfortunate event in the history of MAFFS was the crash of MAFFS 7, at the time operated by the North Carolina Air National Guard. The C-130 crashed on the White Draw Fire, July 1, 2012, as the result of a microburst of turbulent air out of a thunderstorm.  A plane on a previous drop had lost air speed but had recovered and the lead plane for the drop that crashed had been pushed within ten feet of the ground.   The investigation also determined that other contributing factors were the failure of the lead plane and air attack aircrews to provide adequate operational guidance on the approach to the drop.  A significant characteristic is that while many retardant aircraft can “jettison” a load, the C-130 MAFFS are limited to dispersing the load which requires more time and distance than a jettison.

USFS pilot Bill Allred was a frequent lead plane pilot and describes the role of the lead plane as essential for MAFFS flights for safety, efficiency, and economy.  The following is Allred’s description of the operation of the lead plane when flying with MAFFS C-130s:

The USAF pilots are in a foreign world and talk a different language than the fire fighters.  The MAFFS pilots depend on the lead plane to communicate how to enter the congestion of the fire traffic area and provide headings, escape routes and where to make the retardant drop.  The lead plane also communicates with the ground to be prepared for the MAFFS aircraft.  In addition, the lead plane frequently picks up the MAFFS when they approach the fire and leads the MAFFS planes over the drop area. The economy is that the expensive retardant planes, such as the MAFFS and the supertankers, are best used to transport retardant from a base to the fire.  Any minutes spent loitering over a fire is not only a safety concern but is tremendously expensive per minute.  Most MAFFS pilots are comfortable with formation flying and follow close behind the lead plane.

The first lead planes were T-28s or T-34s that had been obtained from military surplus. The planes were replaced with Beechcraft Barons and then King Air Turbine aircraft.   The first USFS lead plane pilot was Gar Leyva who was always identified as “Lead 1” while other pilots were identified by aircraft tail number or an assigned identifier.

MAFFS air tanker
A C-130 Hercules, equipped with the Modular Airborne Firefighting System, drops fire retardant April 27, 2011, above West Texas. MAFFS is capable of dispensing 3,000 gallons of water or fire retardant in less than 5 seconds. (U.S. Air Force photo/Staff Sgt. Eric Harris)

Allred recounts that two MAFFS aircraft of the Wyoming ANG and 24 personnel were sent to Indonesia in October 1997 for six weeks to provide support during an extreme fire season.  Farmers were accustomed to burning for agricultural purposes but in this particularly dry year the fires went up the hills and out of control.  MAFFS liaison plus USFS personnel including two lead plane pilots and MAFFS mechanics flew commercial air to meet the MAFFS C-130s.  The MAFFS met the crew members in Surabaya, East Java, where water drops were successful in firefighting.  Initial water drops only had access to water sources which proved to be corrosive to the aircraft and retardant was eventually shipped to Indonesia for use.  MAFFS resources were then moved to Jakarta for additional missions.  Attempts at drops in Central Kalimantan, Borneo, which was a two-hour flight one-way from Jakarta were prevented by dense smoke. A US Navy pilot in a King Air had flown an undersecretary-of-state to Borneo to watch those missions.  Efforts were then directed to South Sumatra, where the MAFFS were successful in suppressing fires around settlements and in Way Kambas National Park. The actual contribution of the retardant drops to control the massive fires is uncertain; however, the press was good and reports of the great success of the mission were returned through the chain-of-command and, purportedly, to the White House briefing room.

The Air Force Reserve operates a pair of MAFFS C-130 aircraft with personnel out of the 302 Airlift Wing at Peterson Air Force Base in Colorado, and three Air National Guard units in Wyoming, Nevada, and California each provide two. These are the 153rd Airlift Wing, Wyoming Air National Guard, Cheyenne; the 152th Airlift Wing, Nevada Air National Guard, Reno; and the 146th Airlift Wing, California Air National Guard, Port Hueneme.  The MAFFS provide a surge fire-fighting capability – a service that has been used frequently in recent years in support of ground personnel.

MAFFS 2009-2019 gallons per year
MAFFS 2009-2019. NIFC.

The MAFFS can be activated when commercial air tankers are stretched thin and upon the request from the the National Interagency Fire Center (NIFC) in Boise, ID. The six National Guard aircraft can also be activated by the Governors of the three states in which they are based.  The MAFFS operating plan can be found at

MAFFS air tranker
A Modular Airborne Fire Fighting System-equipped C-130 Hercules from the 302nd Airlift Wing drops a load of water April 22, 2013 near Fairplay, Colo. The Air Force Reserve Command’s 302nd AW held its annual MAFFS certification and recertification for C-130 aircrews. (U.S. Air Force photo/Staff Sgt. Nathan Federico)

The MAFFS program is a very visible and beneficial program for the departments involved and presents an exceptional opportunity as a cooperative effort with favorable public relations for all involved.

MAFFS training at Cheyenne
Two Loadmasters check out the MAFFS unit in the cargo hold of the C-130 at Cheyenne, May 7, 2013. Photo by Bill Gabbert.

Richard Hilderbrand, Ph.D., was a Smokejumper in the mid 1960’s and is a Life Member of the National Smokejumper Association.  He was on fires in the Northwest US and Alaska.  He has personally seen TBM aircraft return with tops of trees in their wings and has seen retardant drops from many aircraft.  He has jumped from a Ford Tri-motor, DC-2, DC-3, Twin Beech, Grumman Goose and other jump aircraft.   Special thanks are due to Jim Hickman, Bill Ruskin, Bill Allred, Bill Waldman, Bill Gabbert, and Steve Whitby for their contributions and review! In addition, I thank the many websites referenced in the text for their information; however, any errors are the responsibility of the author.

Frank Prentice, one of the early air tanker pilots, passed away

He was the last surviving member of the air tanker program that began in Willows, California in the 1950s

Frank Prentice in air tanker 21
Frank Prentice in air tanker 21, waits while the aircraft is reloaded at the Ukiah, California airport, probably in the early 1960s. Photo courtesy of Elizabeth Prentice Danley.

Elizabeth Prentice Danley sent us the sad news that her father, Frank Prentice recently passed away. She said he was the last surviving member of the air tanker program that began  in Willows, California back in the 1950s. “To his last days he enjoyed seeing the photos published at Fire Aviation,” she said.

This is the obituary:

Pioneer Air Tanker pilot, former Ukiah resident and original owner of Ace Aerial Service, Frank Prentice, 93, passed away July 16, 2020, at his country home near Chico, CA.

Frank lived in Ukiah from 1960 to 1971.  He was one of the founding members of the first Air Tanker Squadron of pilots flying for the Mendocino National Forest based at the Willows, CA airport.   The group included seven pilots from the Sacramento Valley flying Boeing Stearman 75  and Naval Aircraft Factory N3N’s, converted into agricultural, and then air tanker planes.  The first strike was in 1955 on the Mendenhall fire in the Mendocino National Forest.  By 1956 the seven elite agricultural pilots were flying the converted planes with 170 gallon drum of water/borate and other fire retardants over forest fires all over the state.

In 1958 Frank contracted with California Division of Forest (CDF) and eventually moved his family to Ukiah, establishing Ace Aerial Service as an aircraft maintenance shop in 1960. He continued to fly air tankers during that time.

With billowing towers of smoke and ash obscuring their view, he and his team carried out precision strikes until the fires they were fighting were extinguished.  This practice remains an invaluable technique in wildland firefighting today, and would not have been as widely used or evolved had it not been for the first Air Tanker Squadron.  Frank was the last surviving member of that historic crew.

In 1971 Frank moved back to Willows/Chico area to farm his in-laws’ Walnut & Almond orchard, leaving professional aviation behind.  He and his wife, Lila, were joined by their three children in establishing an impressive legacy near Willows & Chico.

Frank & Lila celebrated their 70th wedding anniversary in November of 2019.  Frank is survived by wife Lila, Chico; Elizabeth Ann Danley (Wade), Willows; Marilee Susan Doolittle (David), Butte Valley; F. Steven Prentice (Yolanda), Chico.  They have 12 grandchildren and 12 great-grandchildren, with #13 due in November.

Services are pending when his ashes will be flown over the orchard at a later date.

Frank Prentice air tanker 21 1956
Frank Prentice in air tanker 21 in 1956. Photo courtesy of Elizabeth Prentice Danley.
Willows air tanker history plaque
Plaque at the Willows, California Airport honoring the early history of using aircraft to fight vegetation fires.

Conair — 50 years in less than 5 minutes

Conair two air tankers dropping
Screenshot from the Conair film

Conair has produced a short video documenting the history of the company. Jeff Berry, Director of Business Development, described it for us:

“2020 is Conair’s 51st fire season supporting wildfire control agencies around the world. We put together a video celebrating those 50 past seasons celebrating all the hard work and innovation that has gone into each and every season.

“The video titled ‘Roots and Wings’ highlights 50 years of Conair’s history in 5 minutes! Those interested in aircraft history and/or aerial firefighting will enjoy the vintage footage from the 1960’s and 70’s through to the present day.”

How 20 smokejumpers were rescued by a 2-passenger helicopter

Higgins Ridge Fire, 1961

Bell 47 helicopter Forest Service
Bell 47 helicopter. Forest Service photo.

Twelve years after 13 smokejumpers were killed on the Mann Gulch Fire 13 miles north-northwest of Helena, Montana, 20 jumpers were entrapped on a fire in northern Idaho 83 miles southwest of Missoula, Montana.

It happened August 4, 1961 on the Higgins Ridge Fire in the Nez Perce National Forest after an eight-man crew from Grangeville, Idaho had jumped in the area, followed by 12 men from the Missoula jumper base, the last arriving at 1 p.m. The fire behavior on the two-acre fire was fairly benign until a passing cold front brought a sudden increase in the wind at 4:15 p.m. which resulted in the fire spreading rapidly. The 20 men took refuge in a previously burned area. As the wind increased to 50 mph the supervisors of the two squads, Dave Perry and Fred “Fritz” Wolfrum, instructed the firefighters to remain calm and to clear an area for themselves in the ashes.

Lightning was bursting from the pyrocumulus cloud over the fire as the men in their newly issued orange fire shirts covered their heads with their arms when the fire burned around them. They helped each other swat out the flames on their clothes during the ember shower.

They did not hear it because of the roar of the fire, but they looked up and saw the red skids of a helicopter. It was a Bell 47B-3 that had seating for three people abreast, with the pilot in the middle.

Below is an excerpt from the April, 1994 edition of “The Static Line” published by the National Smokejumper Association:

…The pilot was Rod Snider of the Johnson Flying Service and he had spotted the men and their orange [fire shirts].

Fritz and Snider quickly organized an evacuation plan. Snider had to drop down vertically and take off the same way because of old snags surrounding the jumpers [a maneuver that requires more power than departing from a ridge]. On the first few trips Rod took out two jumpers on each run, having them ride in the cabin. Then, with the helicopter getting hotter, Rod told them he would take four out on each trip. Two rode in the cabin and two hung on to the [cargo trays]. Rod was able to ferry all 20 jumpers to the Freeman Ridge fire camp. Fritz and Tom were among those on the last trip out.

Some of the jumpers were treated at St. Patricks’s Hospital for smoke-burned eyes. Within several days most of the jumpers who had been on the Higgins Ridge Fire were out jumping on more fires.

Rod Snider and James Van Vleck Nat Museum FS History
L to R: Helicopter pilot Rod Snider with James Van Vleck. Photo by the National Museum of Forest Service History, June, 2019.

In June, 2019 a reunion was held in Missoula for the firefighters that were involved in the Higgins Ridge Fire. Eleven of the jumpers gave oral interviews and participated in a panel discussion at the National Museum of Forest Service History (video of the panel). Mr. Snider made the trip and gave his oral history, but unfortunately had to return home the night before the panel discussion due to a family emergency.

Below are excerpts from an article in The Missoulian, August 2, 2019:

“It was hard to find them,” said Snider, 89, a quiet man who received awards for his heroism but shuns the obvious mantle of hero.

“The wind was really cooking in there and you couldn’t see the heliport all the time to get down. I had to come in high and drop down into it when I could see a little break,” Snider said in an oral history interview before he left town.

What made you risk your life to do it? an interviewer in Missoula asked.

“Oh, it had to be done. It had to be done,” Snider replied. “I don’t know. You just can’t leave guys down in the position that they were in.”

His helicopter, a Bell 47G-3 that Snider christened “Red Legs” for its painted landing skids and support legs, was one of the first with a supercharger. But the overload was nonetheless hard on it, he said.

“I felt a little uneasy, because I knew I’d over-boosted everything, But when they gave an inspection later on they couldn’t find anything wrong with it,” Snider said.

The following year Snider received the Pilot of the Year Award from the Helicopter Association of America in Dallas and the Carnegie Medal for Heroism.

In 1976, the nation’s bicentennial year, Tom Kovalicky, 84, of Grangeville and Stanley, Idaho, successfully nominated Snider for the North American Forest Fire Medal, which was being revived for the first time since 1956. Snider and his wife were flown to New Orleans for the presentation that October. And in 2002 he was inducted into the Museum of Mountain Flying Hall of Fame.

An article about the fire dated February 21, 2003 at the National Smokejumper Association’s website was written by a firefighter who was on the Higgins Ridge Fire a year before he became a smokejumper.

Higgins Ridge Fire
by Gary Shaw

The year was 1961 when cumulus clouds built up every afternoon promising rain, but delivering isolated dry lightning storms. This was the year before I became a smokejumper. It was my second year to work on the Moose Creek District of the Nezperce National Forest. The preceding summer I had spent as a lookout fireman on top of Bailey Mountain. This year I had been working trail crew for a couple of months until the sky erupted at the end of July and left fires all over the district.

My trail partner (Ron) and I had been cutting a trail from the Selway River to Big Rock Mountain and were currently holed up in a cabin there when a helicopter picked us up to transport us to a small fire on Higgins Ridge. We were to meet a crew walking in from Elbow Bend on East Moose Creek. We saw smokejumpers parachute into the fire area on our way to the fire. We landed on the uphill side of the fire, grabbed our shovels and pulaskis and started for the fire. We could see the jumpers’ orange shirts through the smoke.

Before we could get to the fire a large cumulous cloud covered the sun and the wind picked up to 25 or 30 m.p.h. The fire blew up in our faces, and we were forced to retreat back into a large rockslide.

The jumpers weren’t so lucky. They were trapped in the middle of it with no escape route. They dug in, buried their faces in wet bandanas in the dirt, and tried to find air to breath as the fire roared from a manageable 2 acres to a 1280 acre holocaust. It was late evening, and the fire was beautiful to watch. It was crowning, and trees several hundred feet ahead of the fire would begin to tremble and then burst into flame like a fireworks display.

The fire was so hot that canteens of water near the jumpers started exploding. When things looked at their bleakest, the cavalry arrived in the form of Rod Snider(NCSB-51) in a Bell 47G-3B helicopter from Johnson’s Flying Service in Missoula. It was getting dark when he flew into the middle of the fire and started bringing Jumpers out four at a time, which is two more than the maximum the copter was supposed to carry. He had two guys on the seat and two more on the runners. He made five trips into the fire and rescued twenty jumpers. The manifold pressure on the copter engine was 200% above maximum, and when the engine was torn down later, two pistons fell apart. I heard that “Crash” received 20 cases of beer the next week.

My trail partner and I stayed on the fire through mop-up. The other crew arrived without tools, which were to be dropped in by air. Unfortunately, communications left something to be desired. We kept requesting tools and instead received three separate drops of sleeping bags. Each person had a half dozen sleeping bags, but Ron and I were the only ones who had a shovel and pulaski to work on the fire. So we did.

When the tools finally arrived and we got the fire under control, I walked down to the area where the jumpers had been trapped. I found exploded water cans, unexploded gasoline cans (go figure), and a personal gear bag with all their cameras melted together. I could see Minolta, Canon, and Nikon logos on the fused metal and glass. I sent the lot back to Missoula. The fire had been so hot that there were no snags, just pointed stumps and ashes over a foot deep.

I remember two of the rescued jumpers departed the chopper and immediately asked for a cigarette. Now that’s a habit!

I’ve always wondered what that fire looked like from the other side. If anyone reads this that remembers, let me know.

The group that organized the oral history and panel about the Higgins Ridge Fire was organized by the National Museum of Forest Service History. Wildfire Today first wrote about the museum in 2009 five years after they began their effort to raise $10.6 million to build a national museum to commemorate the 100+ year history of the U. S. Forest Service. Their vision began in 1994 when they obtained 36 acres west of the Missoula airport where they hope to build a 30,000 square-foot building.

National Museum of Forest Service History
An architect’s concept of the future National Museum of Forest Service History.

The museum’s fund drive received a significant boost this month when it received a $2 million contribution from the estate of Bill Cannon, a Forest Service retiree.

From the Ravalli Republic:

…Cannon spent most of his Forest Service years in California and Oregon, with an interlude in Hawaii where he was assigned to state and private forestry work. He finished his career in Washington, D.C., where he worked on program planning for the Forest Service’s state and private programs.

Meanwhile, according to a press release announcing his gift, he used his avocation of studying financial markets to become an adept investor.

Cannon became impressed with the National Museum of Forest Service History on a field trip to the site while in Missoula for the 2000 U.S. Forest Service retiree reunion.

Thanks and a tip of the hat go out to Kelly. Typos or errors, report them HERE.

Ontario Air Tanker Base was closed after a jettisoned load of retardant landed on homes and children

Air tanker history from 1977

Ontario Airport C-119 jettisoned fire retardant air Tanker 135
Air Tanker 135, a C-119, jettisoning 2,000 gallons of fire retardant west of the Ontario Airport, July 29, 1977. Photo by J.D. Davis.

When Air Tanker 135 took off from Ontario Airport east of Los Angeles at 5:30 p.m. July 29, 1977 the Mine Fire 16 miles to the south was threatening homes and burning thousands of acres of 60-year old brush in Tin Mine and Hagador Canyons on the southwest edge of Corona.

In a New York Times article about the fire, Corona was described as “a rural town”, and:

A force of 900 firefighters made a successful stand in front of the Village Grove development as flames from the 2,000‐acre blaze came within a football field of homes with price tags of up to $150,000.

Rose Bello was standing outside her house half a mile from the end of the runway at the northwest corner of Belmont Street and Mildred Avenue watching her three-year-old daughter Julie riding a bicycle with a friend. She saw the tanker flying very low, just clearing some power lines. When it passed over her home fire retardant was pouring from the plane.

Ontario Airport C-119 jettisoned fire retardant map
Ontario Airport in an aerial photo taken in 1994 showing the approximate location of the jettisoned retardant. Google Earth.

“The noise was so loud it hurt my ears,” she told a reporter from the Daily Report. “I heard my little girl scream because [the retardant] was in her eyes and all over her clothes — she was just soaked.”

At the time the FAA required restricted air tankers like the C-119 to turn left off the Ontario runway to avoid the heavily populated center of the city. The aircraft had three engines. Two of them were props, Wright R-3350 Duplex-Cyclones, a twin-row, supercharged, air-cooled, radial aircraft engine with 18 cylinders. After the C-119 retired from the military a third engine was added, a turbojet in a nacelle above the fuselage to supply additional power if needed on takeoff or while making a retardant drop.

The pilot, of course, didn’t plan to drop retardant from a very low level on four homes, six cars, children on bicycles, drying laundry, a corn field, and an assortment of trees and sheds. But shortly after take off one of the radial engines developed a runaway propeller, causing the engine to exceed the RPM limits. If not corrected immediately this can cause the propellers to fly off, possibly causing severe damage to the aircraft. When this occurs the pilot will usually reduce the power to the engine and shut off the fuel, a procedure that should prevent additional damage to the engine and the aircraft. But shutting down an engine, especially at low level while climbing and turning, may cause a stall. The pilot jettisoned the 2,000 gallons of retardant, about 9,000 pounds, to reduce the chances of a crash. The aircraft then gained enough altitude to turn and land safely back at the airport.

Ontario Airport C-119 jettisoned fire retardant air Tanker 133
Air Tanker 133, a C-119, making the required left turn after takeoff at the Ontario Airport, July 28, 1977. Photo by J.D. Davis.

J.D. Davis, who took these two aircraft photos, was monitoring a scanner and heard the pilot ask to jettison the load on the runway, but the tower refused permission. The pilot headed toward a corn field near Ms. Bello’s home. That is where most of the retardant landed, plowing up several rows of corn, but part of the load was a little short.

Jim Stumpf was the Deputy Fire Management Officer and Aviation Officer for the nearby Angeles National Forest, the agency that ran the air tanker base at the airport. I asked him what he remembers about the incident:

When I arrived after about 40 minutes (traffic) everyone was really unhappy. CDF [California Department of Forestry] was on scene working clean up and I requested (Lower San Engine I think) to come to the incident to assist in the cleanup. A CDF Batt. Chief and I were directing the clean up and talking with a great deal of the affected residents assuring them that there were no long term effects from the retardant. It would wash off of adults, children, houses, etc. The clothes on the line could be rewashed without any problem.

If I remember, we spent several hours at the scene — CDF and I bought cokes and pizza for our respective crews. The local residents started consuming copious amounts of beer, wine and whiskey so it ended as a block party for all concerned. CDF and USFS turned down the offer to participate in the party. It started out bad and ended up a party. After our street and house cleaning all equipment was returned to their respective stations.

The following day I took Charity Burton to the scene (she was handling claims for the ANF). We talked to as many residents as possible and told them about the claims process. The best I can remember we didn’t get any claims. I drove through the neighborhood a few times on periodic visits to the tanker base, and even talked to some folks who thanked us for being responsive. All was well but they didn’t like tankers flying over their house.

Before the incident 70 individuals and two churches had filed two lawsuits totaling $11.70 million for damage due to noise from jets taking off from the airport, according to an article written in 1977 by Richard Brooks of the San Bernardino Sun.

Back then there were more air tankers than we have today, and they were not forced to move around the country as often following the latest hot, dry, and windy weather. The tanker crews that had been permanently stationed at Ontario perfected the tricky left turn while climbing off the runway, but tanker pilots from other areas were not always as diligent avoiding heavily populated areas. For the rest of the 1977 fire season only the permanent tanker was allowed to use Ontario. After that the base was permanently closed.

Ontario was the southernmost base that could support and refill large air tankers, so closing it reduced their ability to quickly and aggressively respond to fires in Los Angeles, Riverside, and San Diego Counties.


In 1987 a C-119 (N48076) with the same tanker number, 135,  crashed while working the Whalen Fire on the Shasta-Trinity National Forest. Killed were Hawkins & Powers pilots Bill Berg and Charles Peterson, and mechanic Stephen Harrell. The crash was result of an inflight failure, with the right wing, the left wing tip, and the tail boom separating from the aircraft during a retardant run.

A big thank you goes out to J.D. Davis who supplied information about the incident and the C-119 photos.

Five more PB4Y-2 air tankers

PB4Y-2 air tanker
PB4Y-2 Air Tanker 121, N2871G, at Hemet, California, September 15, 1979. Photo by JD Davis. Anyone know the story of the polka dots?

In our continuing series of looking back at photos of historic air tankers, today we are featuring five PB4Y-2 Privateers: Tankers 30, 50, 121, 123, and 124.  The photos of the aircraft seen here were furnished by the Flight Test Museum at Edwards Air Force Base except for the ones credited to JD Davis. Thanks JD!

PB4Y-2 Air Tanker
PB4Y-2 Air Tanker 50, N7237C, at Lancaster, California, August 25, 1972.
PB4Y-2 Air Tanker
PB4Y-2 Air Tanker 30, N3739G, at Lancaster, California November 1980. Photo by JD Davis.
PB4Y-2, Tanker 30, N3739G
A PB4Y-2, Tanker 30, N3739G, at Hemet, California, July 17, 1980. Photo by JD Davis.
PB4Y-2 Air Tanker
PB4Y-2 Air Tanker 123, N7620C, at San Bernardino, California July 25, 1999. Photo by JD Davis.
PB4Y-2 Air Tanker
PB4Y-2 Air Tanker 124, N2672G?, at Hemet, California, August, 1980. Photo by JD Davis.
PB4Y-2 air tanker
PB4Y-2 Air Tanker 50, N7237C, at Lancaster, California, August 25, 1972.
PB4Y-2 Air Tanker
A PB4Y-2 Air Tanker at Reno, Nevada, 1976.