Document
OAS - 43 A (12/12)
Interagency Aviation
Accident Prevention Bulletin
No. IA APB 1 8 - 0 2 March 20 , 2018 Page 1 of 2 Subject: Smoke Column Hazards Area of Concern: Fire Suppression Operations Distribution: All Aviation Activities Discussion : In a recent accident in California , a non - federal firefighting helicopter was conducting water drops supporting residential structure protection when the pilot flew into a smoke column. The h elicopter began an uncommanded yaw to the right and rate of descent increased.
The pilot reported that he released the water but had minimal control of the helicopter. The main rotor blades, tail boom and tail rotor all impacted trees during the sequence. After hitting the tree s , the uncom manded yaw appeared to decrease. T he pilot was able to regain control o f the helicopter and flew approxima tely one mile , landing safely at a school athletic field. The pilot reported no pre - impact mechanical issues or malfunctions that would have precluded normal operation ( NTSB ANC17LA051 ) .
Smoke columns are the vertical development of smoke emitting from a fire and represent an ascendi ng air column (updraft). It i s imperative that aircrews understand the hazards associated with smoke columns during aerial firefigh ting operations , regardless of aircraft type . The SAFECOM database has at least 14 inter - agency submissions in the last ten years involving safety issues with both fixed - wing and helicopters operating in or near smoke columns. Here are a few key p oints to keep in mind : Smoke columns can present inadvertent instrument m eteorological conditions (IMC), which are especially dangerous when flying low over terrain.
No. IA APB 1 8 - 0 2 March 20 , 2018 Page 2 of 2 Loss of horizontal and vertical visibility and situational awareness is possible during inadvertent IMC, which can result in controlled flight into terrain ( CFIT) or spatial disorientation .
The hot temperature s in a smoke column can significantly reduce aircraft performance . The increase in density altitude can result in h azardous conditions for helicopters such as a loss of tail rotor effectiveness (LTE), settling with power, and decreased power available . The density altitude for performance planning does not include the temperatures of the superheate d gases that exist in side of a smoke column.
With the extremely hot temperature in the smoke column, aircraft components (such as composite s, plastics, electronics, etc.) could sustain heat damage .
With the vertical development of the smoke column, foreign object debris (F OD) such as ash, trash, and tree branches can be present, causing damage to aircraft . Additionally, FOD ing estion into critical components ( pitot tubes, temperature sensors, en gine compressors, etc.)
can have catastrophic results .
Aircrew members can b e e xposed to smoke inhalation while in the smoke column.
The hazards listed abo ve are present for all smoke columns, regardless of size.
Coordinate with aerial supervision and/or ground operations personnel on appropriate ingr ess and egress routes for suppr ession drops that avoid flying through a smoke column and where the aircrew can positively identify the hazards along with the start and exit point of the drop.
Review IASA 16 - 02 “ How to Properly Refuse Risk in Aviation . ” Always utilize standard aviation “see and avoid” visual flight rules (VFR) p rocedures when conducting drops near smoke columns. Minimum altitudes, operating airspeeds, terrain, and environmental factors must always be considered. Review IASA 17 - 03 “ Aircraft Operations in Poor Visibility. ”
Where there’s smoke, there’s fire. So stay clear !
/s/ J. Kent Hamilton /s/ Keith Raley John Kent Hamilton Keith Raley Branch Chief, Aviation Chief, Aviation Safety, Training, Program Safety Management Systems Evaluations and Qua lity Management USDA Forest Service DOI, Office of Aviation Services