What happened
NTSB summary, verbatimBased on crew reports and verified with images from the crew and the EAFR, the flight crew lost the use of three of the five head down displays following a lightning strike. The crew followed published procedures, however the procedures did not contain a checklist related to a partial loss of displays. After the crew elected to follow the "Loss of All Displays Checklist", none of the affected displays recovered to an operational state. The crew did land the aircraft successfully using the remaining displays available to the crew. All of the displays did recover normal operation after accomplishing a power cycle to the displays while the aircraft was on the ground. No procedures existed for a power reset of the displays to occur while in flight, which most likely would have resulted in a restoration of the displays. Reviewing the design and display certification requirements, the displays passed their respective certification testing required by the FAA. Supplemental testing by the investigation also showed the displays operating satisfactorily at testing levels that were above levels specified in the original certification of the aircraft and system. However, when subjecting the displays to testing that was based on different standardized system level testing (typically associated with military aircraft) that was not required to be conducted for display unit or aircraft certification, the failure could be repeated. This failure was attributed to the display's response to a rapid transient radiated electric field. The electrical field analysis of the aircraft cockpit confirmed that similar electrical transients can be present during certain lightning strikes experienced by an aircraft. Although the displays passed the required certification testing required by the FAA, it was determined that certain environmental conditions exist that could cause adverse conditions of the display operation resulting in a loss of the display.
Photographs
4the aircraft, and what the investigators foundPhotographs are NTSB docket attachments — works of the US government, in the public domain. Captions are the Board’s own.
Probable cause
the Board's determinationA shutdown of the displays due to the inability to operate through a rapid transient radiated electric field brought on by a near field lightning strike. Contributing to the loss of displays for the remainder of the flight was the lack of guidance to the crew to perform a controlled power reset to the display.
Occurrence sequence
2 stepsNTSB coding · CICTT taxonomy- 1 · Initial climbOther weather encounter
- 2 · Initial climbFlight instrument malf/faildefining event
Findings
1 causal · 1 contributing- CAUSEAircraft › Aircraft systems › Indicating/recording systems › Central display — Failure
- FACTORAircraft › Aircraft systems › Indicating/recording systems › Central display — Capability exceeded
Sequence of events
1 timed eventsfrom the FDR factual report · claude-sonnet-5- approximately 1300 UTCClimb (approximately six minutes after take-off)p.1Aircraft struck by lightning; three of five primary display units went blank, a status message related to a power distribution channel was displayed, and the captain's forward windshield heat became inoperative. Standby instruments and heads up displays (HUD) were unaffected.
NTSB analysis
from the final reportBased on crew reports and verified with images from the crew and the EAFR, the flight crew lost the use of three of the five head down displays following a lightning strike. The crew followed published procedures, however the procedures did not contain a checklist related to a partial loss of displays. After the crew elected to follow the "Loss of All Displays Checklist", none of the affected displays recovered to an operational state. The crew did land the aircraft successfully using the remaining displays available to the crew. All of the displays did recover normal operation after accomplishing a power cycle to the displays while the aircraft was on the ground. No procedures existed for a power reset of the displays to occur while in flight, which most likely would have resulted in a restoration of the displays. Reviewing the design and display certification requirements, the displays passed their respective certification testing required by the FAA. Supplemental testing by the investigation also showed the displays operating satisfactorily at testing levels that were above levels specified in the original certification of the aircraft and system. However, when subjecting the displays to testing that was based on different standardized system level testing (typically associated with military aircraft) that was not required to be conducted for display unit or aircraft certification, the failure could be repeated. This failure was attributed to the display's response to a rapid transient radiated electric field. The electrical field analysis of the aircraft cockpit confirmed that similar electrical transients can be present during certain lightning strikes experienced by an aircraft. Although the displays passed the required certification testing required by the FAA, it was determined that certain environmental conditions exist that could cause adverse conditions of the display operation resulting in a loss of the display.