Re: Peruvian 757 crash

Date:         01 Dec 96 04:08:53 
From:         Reid Fairburn <cr_king@cr_king.seanet.com>
References:   1 2 3
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At 06:18 AM 11/25/96, you wrote:
>ethan@cs.wisc.edu wrote:
>> :   Scheduled 14 CFR 129 operation of MARTINAIR HOLLAND (D.B.A. MARTINAIR)
>> :   Incident occurred MAY-28-96 at BOSTON, MA
>> :   Aircraft: Boeing 767-31AER, registration: PHMCH
>> :   Injuries: 202 Uninjured.
>
><story of 767-300 glass cockpit instruments being erratic and pilots
>choosing to land at Boston because failures had become too serious>
>
>When a computer starts acting up, the easiest way to fix it is to reboot
>it.
>
>Are there not facilities/instructions on how to reboot all your
>computers DURING a flight ? I realise that there would be problems
>estimating your current position once computers are back up and telling
>the computer that it had awaken right in the middle of a flight.
>
>I was once on a A320 where the pilots explained to us the PAX that the
>"computer was not cooperating" and that they had to shut it down and
>restart it from scratch and that this would take 8 minutes and that we
>would thus be leaving a bit late. I assume a good part of the 8 minutes
>was running a checklist and recalibrating stuff, correct ?

Normally, this is not done.  The reason being is that the computers are
not required in most cases, to complete the flight and if a pilot was to
pull a wrong circuit breaker things could definitely get worse!

When and if this is to be done, it involves just a removal of power from
the FMC (Flight Management Computer) for a short period of time...say 30
seconds.  Then when power is reapplied, the computer will pick up from
where it left off.  In some cases, you will have to enter the flight plan
again but most of the time it will still be available.  Position
information comes from the IRS/GPS and will be available as soon as the
computer reboots through it's initialization checks.  Total time to back
up and  running can be as short as 2 to 3 minutes.  Not a big deal unless
you are counting on it to navigate you through the rocks.

I suspect that the incident you are referring to might have involved an
IRS problem which is best fixed by doing a complete realign...this requires
the airplane to sit and feel the rotational effects of the earth and
gravity...which is normally up to 10 min.  This has nothing to do with
the FMC who is just a user of this information about position.

Reid Fairburn
Creative Kingdom, Inc.
cr_king@cr_king.seanet.com
206-946-4815