Hello Admiral Cloudberg, I´m not a native English speaker so the mistake probably lies with me, but if the flight management was inadequate, I would expected it to read:
""All of these errors could be summarised under what the NTSB called "inadequate flight management.”".
If you as the author would have judged the remarks of the NTSB inadequate or understated, I would have written like it is written.
"All of these errors could be summarised under what the NTSB called inadequate “flight management.”".
At the moment I´m not sure if the flight management was inadequate according to the NTSB, or the NTSB-reference to flight management is inadequate according to you. You might not consider it worthy of the word "flight management", and I would have to concur :)