Re: SAS MD-81 crash report, December 1991

From:         d.alan.johnson@larc.nasa.gov (Dave J.)
Organization: NASA Langley Research Center, Hampton, VA  USA
Date:         17 Nov 93 15:34:35 PST
References:   1
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>According to Flight International, 10 NOVEMBER 1993, "an automatic
>engine-control function in the McDonnell Douglas MD-81, of which the
>operating airline was unaware, was a major factor in the Scandinavian
>Airlines System (SAS) accident near Stockholm, Sweden, in December 1991,
>says the official report into the accident"

>In summary, it seems that the airline failed to detect clear ice on the
>wings before takeoff. The ice broke free and entered the engines damaging the
>fan stages. This caused the right engine to surge. The pilots retarded the
>right throttle. The automatic thrust-restoration system ATR caused both
>throttles to advance without the pilots noticing, making the surging worse
>in the right engine and starting surging in the left. The surges destroyed
>the engines.

>It seems that SAS were unaware of the ATR, which was documented but in a
>section of the production flight-procedure manual dealing with noise
>abatement. SAS VP Johan Juhlin is reported as saying "We did not order it.
>It was hidden in the computer. The only way to disconnect the ATR was to
>disconnect the whole autothrottle system."

Could you be referring to the "ARTs" system - automatic reserve thrust?
It will fire in the takeoff mode based on certain logic such as altitude rate, 
radar altitude and airspeed.