Diesel Exhaust Fluid (DEF) Contamination Risk Alert

The issue of Diesel Exhaust Fluid (DEF) contamination of jet fuel has proven to be a very serious threat to the safety of flight. There have been several incidents where DEF was accidentally injected into jet fuel instead of Fuel System Icing Inhibitor (FSII). These incidents have led to inflight emergencies, including both partial and complete engine failures, nine emergency landings, and at least one aircraft deadstick landing – narrowly avoiding a tragic outcome.

NATA urges its members and all refueling operators that utilize DEF and FSII (DiEGME, PRIST®, DICE®) to review their storage, handling, and personnel training procedures to prevent DEF contamination of jet fuel. The Federal Aviation Administration (FAA) has released a Special Airworthiness Information Bulletin (SAIB) that addresses the dangers of DEF contaminated aviation fuel.

NATA offers a free operational best practice on DEF Handling and Contamination prevention and has DEF contamination prevention training available through our Safety 1st Training Center.

For questions regarding DEF Contamination Prevention or any of the resources described in this alert, please contact safety1st@nata.aero.


NATA Safety 1st Alert
DEF Handling and Contamination Prevention
NTSB Alert
Aircraft Diesel Exhaust Fluid Contamination Working Group Report & Recommendations
Safety Risk Management DEF Report - August 30, 2019
DEFKit - DEF in FSII Test Kit