Re: MD-11 Landing/Flare Behavior

Date:         05 Aug 97 17:45:50 
From:         "Pete Adler" <zflyr@ibm.net>
References:   1
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In article <airliners.1997.1664@ohare.Chicago.COM>
           kranz@sprintmail.com "Matthew Kranz" writes:
>Thursday morning's crash of the FedEx MD-11 in Newark has prompted me to
>pose a question to the group. Does the MD-11 have less-than-optimum
>flare and landing characteristics? In addition to FedEx's crash (and
>previous hard landing) of N611FE, I saw a Delta MD-11 make an arrival (I
>wouldn't call it a landing <g>) at CVG a few months ago that was,
>obviously quite hard. The plane touched down heavily somewhere between
>the threshold and the 500-foot mark after little or no flare, and
>bounced 5-10 feet in the air before touching down again.

There have been problems associated with the MD-11 especially in the
flare regime. This occurs with both autoland, and manual approaches. It
is my understanding that primarily this occurs because there was a
reduction in the size of the elevator to reduce both drag and weight on
the aircraft. This reduction allowed the aircraft to meet its promised
spec range and payload guarantees. Unfortunately, the aircraft became
dynamically unstable in certain regimes of flight. This was resolved
with a software change that supposedly resolved the instability issues.
The first few hard-landing incidents that occured with the MD were with
auto-land engaged. This prompted a ban on auto-lands and manual
approaches only. Shortly thereafter, another hard-landing with auto-land
prompted a ban on auto-lands with manually flown approaches only. This
also did not solve the problem.