RE: Cali: "planned track error" would be another recommendation ?

Date view Thread view Subject view Author view Attachment view

Date: Mon 21 Jul 2003 - 08:41:51 BST

An observation and aside to the main discussion:

nm denotes a unit of a nano-meter
Nm - Newton meter and 
NM - a nautical mile.

"nmi" is an older version of nautical mile which is still probably
While context in this case makes the meaning clear, in many documents the
use of "nm"
for nautical mile is confusing, particularly where the parameters for modern
sensors are also being specified. 


-----Original Message-----
From: Peter B. Ladkin [mailto:ladkin(at)]
Sent: Monday, 21 July 2003 4:24 PM
To: mpeixot
Cc: safety-critical(at)
Subject: Re: Cali: "planned track error" would be another recommendation

     Couldn't FMS logic be defined to raise an alarm if a beacon or
     destination is too far from original intended destination ?

Well, of course this could be done. The question is what it would

First, this situation was unique, as far as the NTSB could tell.
There were some twenty or so NDB pairs in the world which had the
same identifier and were within reception range of some point; the
Cali/Bogota ROMEO/ROZO pair was the only pair whose frequencies were
also identical. So ID/frequency served to separate all such pairs,
with the exception of ROMEO/ROZO. ROZO's name and ID have now been

Second, the procedure performed by the Cali crew, deleting a previous
route and picking a new one to a navaid some 130nm away, is
undertaken as a matter of routine, when an airport is under landing
visibility minimums or is subject to extreme weather, and the
aircraft diverts to the alternate airport (which must be named in
the flight plan before departure). Prompting pilots for confirmation,
or even issuing a warning, in a routine flight phase when the crew
is likely to be busy, is not generally regarded as a good thing.
It distracts the pilots mostly needlessly, and it is likely to
induce an automatic response (confirmation without checking).


Peter B. Ladkin PhD FBCS CW(hon)
Professor of Computer Networks and Distributed Systems,
Faculty of Technology, University of Bielefeld, 33594 Bielefeld, Germany
Tel (Vx/msg/Fax) +49 (0)521 880 7319

Date view Thread view Subject view Author view Attachment view