Re: Can an Airbus 320/321/330/340 perform a controlled glide?

Date:         09 Apr 97 03:09:27 
From:         Pete Mellor <pm@csr.city.ac.uk>
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Dave Smith <david.h.smith@gecm.com> asked on Sun Mar 30 13:52:54 1997:-

> With no mechanical backup can an Airbus that has lost the computers,
> for whatever reason, be glided to a safe landing?
>
> Intuitively I assume the case is no, but wouldn't this give people
> like the FAA and CAA concern regarding Airworthiness certificates
> and the like?

In the event of loss of all 5 computers in the Electrical Flight
Control System (EFCS) the crew can control pitch by moving the
Trimmable Horizontal Stabiliser (THS) using the pitch trim
wheels, and yaw (and roll to some extent) by operating the rudder
via the pedals. Connection to both of these surfaces is mechanical
(although in normal operation, they can also be operated
automatically). The crew can also vary the thrust of the engines
independently of each other.

It is a certification requirement that the aircraft can be landed
using this "mechanical back-up" alone. Pilots are trained in its
use on a simulator (I think). It has also been done on a test flight
(again, I think). There has never been a case of loss of all 5 EFCS
boxes during a scheduled flight.

Peter Mellor, Centre for Software Reliability, City University, Northampton
Square, London EC1V 0HB, UK. Tel: +44 (171) 477-8422, Fax: +44 (171) 477-8585
E-mail: p.mellor@csr.city.ac.uk
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