Safety Alert issued for low retardant drops

On May 20, 2019 officials within the US Forest Service and the Department of the Interior released a Safety Alert regarding the safe height for retardant drops. This could be related to the fatality following a drop by the 747 Very Large Air Tanker  on the Ranch Fire in 2018 east of Ukiah, California, the drop by a DC-10 VLAT on the Liberty Fire in 2017 that damaged the roof and knocked out windows in a home and vehicle east of Murrieta, California, and perhaps also a drop by an MD87 in 2018 on the Boxcar Fire near Maupin, Oregon.


Retardant safety alert

Subject: Retardant Safe Drop Height
Area of Concern: Safety of Ground Personnel
Distribution: All Fire Aviation Operations

Discussion: The optimum release height or safe drop height for fire retardant can be defined as the distance below the airtanker at which the retardant begins to fall vertically (Figure 1). When the retardant is dropped, the velocity of the aircraft is imparted to the retardant. In other words, the retardant is traveling at the same speed as the aircraft. When the retardant has lost all of its forward momentum and is falling vertically as a heavy rain, the danger to firefighters is reduced and effectiveness is increased.

retardant drop heightIf a Very Large Airtanker (VLAT) is traveling at 150 knots and is well below the recommended safe drop altitude, the 8,000-19,000 gallons of retardant released will impact the earth at a similar velocity. If personnel are underneath the retardant pattern, they can be struck with the fast moving retardant, broken trees, other debris, or all of it. ¹Figure 2 shows a drop that was released below the safe drop height maintaining considerable velocity as it reached the ground. The force of the retardant dropped from too low of an altitude can topple trees up to 90 feet in height and a trunk a foot in diameter.

Page 2

Drop Safety Considerations

  •  Aerial drops are hazardous and caution should be used when working in areas with aircraft operations. Serious injury and/or property damage can occur from any excessively low tanker drop, including S2’s and SEATs.
  • The Red Book, Interagency Aerial Supervision Guide and the Interagency Incident Response Guide all have slightly different verbiage, but basically state that the Aerial Supervisor/ASM/Airtanker pilot and the identified ground contact/personnel must ensure all fireline personnel are notified of impending aerial drops (fixed wing and rotary wing).
  • Pilots must ensure that they have received confirmation that all people and moveable property have been cleared prior to commencing drops of any fire-fighting agent (water, foam, retardant or gel).
  • Pilots must ensure they do not drop below a safe drop height. This becomes more difficult in mountainous terrain or if the aircraft is not equipped with a radar altimeter so it’s imperative that pilots develop the site picture and practice proper technique for the appropriate drop height for their respective aircraft.
  • Pilots must remember that lower is not always better. Drops that are too low fail to provide retardant in an efficient manner with the desired coverage level. This is not only dangerous, but fails to provide the support ground crews require.
  • Fireline personnel must maintain situational awareness. Personnel who are using cell phones to video the aerial retardant drops can easily become distracted by recording the retardant drops which impairs their ability to recognize the hazards and take appropriate action should it be necessary (Figure 3).
  • Keep in mind that a pilot will, at any time, jettison the entire load quickly during an in-flight emergency.

Firefighting is not a spectator sport. Be alert, be ready, be safe.

(The document was signed by Keith Raley, Chief, Aviation Safety, Training, Program Evaluation, and Quality Management for the DOI Office of Aviation Services; and by Sean Aidukas, Acting Branch Chief, Aviation Safety Management Systems, US Forest Service.)

1. Firefighter Injuries and Fatality, CAL FIRE GREEN SHEET, August 13, 2018. 18-CA-MEU-008674, 18-CA-MEU-009504. References: Incident Response Pocket Guide, NWCG, April 2018. Greg Lovellette, Safe Drop Height for Fixed-Wing Airtankers, March 2000; PMS 505: Interagency Aerial Supervisors Guide, April 2017; Interagency Standards for Fire and Fire Aviation Operations (Red Book) January 2019.

Green Sheet report released on fatality following retardant drop

The report concluded that a low drop by the 747 Supertanker uprooted and broke off trees and limbs

Diagram fatality air tanker drop Green Sheet
Diagram from the Green Sheet.

(Originally published at 4:15 MDT September 14, 2018, and updated at 7:43 MDT September 14, 2018)

The California Department of Forestry and Fire Protection (CAL FIRE) has released what they call a “Green Sheet” report about the fatality and injuries that were caused by falling tree debris resulting from an air tanker’s retardant drop. The accident occurred on the Ranch Fire which was part of the Mendocino Complex of Fires east of Ukiah, California. The report was uploaded to the Wildland Fire Lessons Learned Center on September 13, 2018 exactly one month after the August 13 accident.

A firefighter from Utah, Draper City Battalion Chief Matthew Burchett, was killed when a low drop uprooted an 87-foot tall tree that fell on him. Three other firefighters had different assortments of injuries from sheered-off trees and limbs, including broken ribs, deep muscle contusions, ligament damage to extremities, scratches, and abrasions.

747 supertanker palmer fire
File photo: The 747 SuperTanker drops on the Palmer Fire south of Calimesa and Yucaipa in southern California, September 2, 2017. Photo by Cy Phenice, used with permission.

Standard procedure is for firefighters to leave an area before an air tanker drops. The report said the personnel on that Division were told twice that day to not be under drops — once in a morning Division break-out briefing, and again on the radio before the fatal drop and three others from large air tankers were made in the area. It was not confirmed that all supervisors heard the order on the radio to evacuate the drop area.

One of the “Incidental Issues / Lessons Learned” in the report mentioned that some firefighters like to record video of air tanker drops:

Fireline personnel have used their cell phones to video the aerial retardant drops. The focus on recording the retardant drops on video may distract firefighters. This activity may impair their ability to recognize the hazards and take appropriate evasive action possibly reducing or eliminating injuries.

The air tanker that made the drop was T-944, a 747-400 that can carry up to 19,200 gallons. Instead of a more conventional gravity-powered retardant delivery system, the aircraft has pressurized equipment that forces the retardant out of the tanks using compressed air. This is similar to the MAFFS air tankers. When a drop is made from the recommended height the retardant hits the ground as a mist, falling vertically, rather than the larger droplets you see with a gravity tank.

In this case, according to the report, the drop was made from approximately 100 feet above the tree tops. The report stated:

The Aerial Supervision Module (ASM) identified the drop path to the VLAT by use of a smoke trail. The VLAT initiated the retardant drop as identified by the smoke trail. Obscured by heavy vegetation and unknown to the VLAT pilot, a rise in elevation occurred along the flight path. This rise in elevation resulted in the retardant drop only being approximately 100 feet above the treetops at the accident site.

When a drop is made from a very low altitude with any air tanker, the retardant is still moving forward almost as fast as the aircraft, as seen in this drop. If it is still moving forward there will be “shadows” that are free of retardant on the back side of vegetation, reducing the effectiveness of the drop. From a proper height retardant will gradually slow from air resistance, move in an arc and ideally will be falling gently straight down before it hits the ground. Another example of a low drop was on the Liberty Fire in Southern California in 2017 that dislodged dozens of ceramic roofing tiles on a residence and blew out several windows allowing a great deal of retardant to enter the home.

We reached out with some questions to Global Supertanker, the company that operates the 747 Supertanker, and they gave us this statement:

We’re heartbroken for the families, friends and colleagues of Chief Burchett and the other brave firefighters who were injured during their recent work on the Mendocino Complex Fire. As proud members of the wildland firefighting community, we, too, have lost a brother.

On August 13, 2018, Global SuperTanker Services, LLC acted within procedural and operational parameters. The subject drop was initiated at the location requested by the Aerial Supervision Module (ASM) after Global SuperTanker Services, LLC was advised that the line was clear.

The former President and CEO of the company, Jim Wheeler, no longer works there as of September 1, 2018. The company is owned by Alterna Capital Partners LLC, of Wilton, Conn.

(Updated at 7:43 MDT September 14, 2018 to include the statement from Global Supertanker that we received at 7:35 p.m. MDT September 14, 2018)

Air Tanker 101 drops on the Boxcar Fire

I hope no one was under that drop (the video on the left) by an MD-87 on the Boxcar Fire near Maupin, Oregon.

In case the video on the left does not work, try it a this link. But below is a screen grab:

MD-87 Drop
T-101, and MD-87, make a low drop on the Boxcar Fire near Maupin, Oregon, June, 2018. By Katie Hemphill-Pearcy.

Homeowner films DC-10 retardant drop on his house

This was on the Liberty Fire December 7 east of Murrieta, California.


(UPDATED September 14, 2018)

The photos below from Flashover.com (referred to in the comments below) show the results of a low drop by a DC-10 on the Liberty Fire, December 7, 2017. They were taken by Jenny Crane.

DC-10 low retardant drop
The result of a low drop by a DC-10, Liberty Fire, 2017.
DC-10 low retardant drop
The result of a low drop by a DC-10, Liberty Fire, 2017.