Air Tanker Safety Study

Air Safety Week, Oct 13, 2008

NASA has partnered with the U.S. Forest Service to examine the mission suitability of Boeing 747 and McDonnell Douglas DC-10 fire retardant delivery aircraft.

The aircraft under study are a DC-10 belonging to 10 Tanker Air Carrier and a 747 owned by Evergreen International Aviation. The DC-10 tanker has already been successfully employed by the California Department of Forestry and Fire Protection for wildfire suppression missions.

NASA's Dryden Flight Research Center at Edwards AFB, CA, is working with the Forest Service to help determine the safe flight envelope for these very large air tanker aircraft for both the USFS and the U.S. Department of the Interior. Additionally, NASA Dryden will recommend operational usage regimes, policies and procedures for the aircraft.

The Forest Service and the Interior Department asked NASA for help because of its expertise conducting test flights. Mark Dickerson, Dryden project manager, calls this important work. "The entire team is very excited about helping the forest service with this effort. It is a bit different from our typical research projects, but we all enjoy being able to help find new tools to fight wildfires," Dickerson said.

As project lead, NASA Dryden is performing operational test and evaluation assessments. Project engineers will report findings and recommendations on these aircraft in cooperation with NASA Ames Research Center at Moffett Field, CA. NASA Ames engineers are supporting the effort with pilot- in-the-loop simulations and are coordinating simulator models, flight profiles & data analysis with project staff at NASA Dryden.

Engineers at NASA Dryden will also develop, implement, and direct an evaluation test plan for use in flight test and in simulation. The test plan will be designed to evaluate the suitability of large tanker aircraft for the firefighting mission environment.

Based on this analysis, NASA will propose appropriate interim flight envelope limitations to enhance safety and operational utility in the fire retardant delivery mission.

NASA Dryden personnel are working with crews of the large tanker aircraft to capture flight validation data, assess the effectiveness of proposed procedures, and refine those as required.

The final project report will include initial recommendations for such factors as flight over various terrain types, density altitude limits, turbulence, and horizontal wind shear limits.

The very large air tankers are used to supplement smaller tanker aircraft.

On August 27, a single-engine Air Tractor AT-802A (N189LA) was totaled after crashing near Meeker, CO. The pilot, the sole occupant, received minor injuries. The special-use aircraft was registered to Minuteman Aerial Application, Missoula, Montana, and operated by the Bureau of Land Management (BLM) under a firefighting contract.

According to the pilot, while making a pass to drop fire retardant, the airplane's cockpit access hatch opened. Unable to close the hatch, the pilot elected to attempt another pass to jettison his remaining retardant before returning back to the airport. But during the second pass his aircraft stalled and impacted terrain. The airplane came to rest in an upright position and the pilot was able to exit unassisted.

Photographs provided to the NTSB investigator-in-charge (IIC) revealed that the airplane's wings, engine, and left horizontal stabilizer separated from the fuselage during the accident.

On Sept. 1, another aerial tanker was lost, killing two pilots and a flight mechanic.

The aircraft had just departed Reno-Stead Airport. The former U.S. Navy submarine hunter owned by Neptune Aviation of Missoula, MT, had made one flight over a wildfire south of Lake Tahoe that morning before it returned to the airport to refuel and load fire retardant.

The Lockheed SP-2H was destroyed after impacting terrain following a loss of power and loss of control about two miles northwest of the airport. An air tanker base employee watched the airplane take off. At an elevation estimated to be between 100-300 feet above the ground, he observed the left jet engine emitting flames and the left wing engulfed in fire. The witness further reported that about two seconds later the tanker entered a left wing down attitude before impacting terrain and bursting into flames.

A report from the Agriculture Department's inspector general says U.S. Forest Service aircraft have been involved in preventable crashes over the year and remain at risk for more.

The IG investigators made numerous recommendations that the USFS accept, but Forest Service officials resist one recommendation that the FAA take a bigger role in certifying forest service aerial tankers and other aerial firefighting equipment.

The IG report on the Forest Service's Air Safety Program considered whether the USFS minimized the risk of accidents and made effective use of aerial resources.

"Overall, we concluded that FS has made strides toward improving its air safety program, but still needs to develop and implement an airworthiness assessment, inspection, and maintenance program geared towards the particular demands of the firefighting flight environment." As implemented, the FS must ensure that all aircraft it employs "are held to the improved standards."