Can EFIS / EFMS lead to removing basic safety checks?

This question is the result of the wrong runway issue at LEX last
weekend.



Not having flown an EFIS or EFMS myself, I'm not sure of the "into
position checklist items". For example, in a standard steam-gauge panel
one of the last things we check is to align the directional gyro with
the runway heading and compass. With an EFIS or EFMS, is there any such
last minute check, or is the heading assumed to be correct because it
was aligned by the GPS when the bird came out of the chocks?



If there is no requirement to manually align and verify runway heading,
compass, and EFIS/EFMS then our technological advances have
inadvertently removed one of our heretofore unrecognized safety checks.



I heard some retired commuter pilot on the news last weekend suggesting
that the only way to prevent this in the future is to put traffic lights
(stop / go) on the end of every runway. I absolutely got the impression
that he was there to convince the public that it is almost impossible
for the pilots to get it right and the lack of the traffic signal was
the whole cause of the problem. Sort of the typical "not my fault"
attitude.

In article 004101c6ce26$e77966d0$4001a8c0@omnibook6100,
"Jim Carter" wrote:

Not having flown an EFIS or EFMS myself, I'm not sure of the "into
position checklist items". For example, in a standard steam-gauge panel
one of the last things we check is to align the directional gyro with
the runway heading and compass. With an EFIS or EFMS, is there any such
last minute check, or is the heading assumed to be correct because it
was aligned by the GPS when the bird came out of the chocks?

No, the GPS doesn't align the heading gyro -- an electronic flux gate
does. There are two independent heading gyros, and two independent flux
gates to set them. If there's a disagreement of more than a few
degrees, an error flag will come up, and the crew will troubleshoot to
see where the error lies.

So yes, on that type of system, the heading is assumed to be correct.
The odds of both flux gates failing at exactly the same time, but to
exactly the same erroneous heading, are about nil.

So yes, on that type of system, the heading is assumed to be correct.
The odds of both flux gates failing at exactly the same time, but to
exactly the same erroneous heading, are about nil.

Are the flux gate sensors located near each other?

Jose
--
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for Email, make the obvious change in the address.

I heard some retired commuter pilot on the news last weekend suggesting
that the only way to prevent this in the future is to put traffic lights
(stop / go) on the end of every runway.

I saw this demoed somewhere (but I don't remember where). It was pretty
cool. There was a row of read lights across the taxiway access to the
runway until cleared for takeoff.

-Robert

In article ,
Jose wrote:

Are the flux gate sensors located near each other?

Depends on the model of airplane, I'm sure. Though I don't know the CRJ
enough to answer with respect to it, on my airplane there's one near
each wingtip, purposely placed as far from interference as possible.

Are the flux gate sensors located near each other?

Depends on the model of airplane, I'm sure.

I would expect that for those models where the sensors are close
together, the right stray magnetism (whether deliberate or accidental)
could cause both redundant systems to have the same error.

Jose
--
The monkey turns the crank and thinks he's making the music.
for Email, make the obvious change in the address.

Jose wrote:

Are the flux gate sensors located near each other?


Depends on the model of airplane, I'm sure.


I would expect that for those models where the sensors are close
together, the right stray magnetism (whether deliberate or accidental)
could cause both redundant systems to have the same error.

Jose

A whole lot of design work goes into isolating those flux gates. And,
most of the mainline airliners have three IRUs, so they don't even use
flux gates. Everything is in true, then automatically converted to
local magnetic for display purposes.

Jim Carter wrote:


I heard some retired commuter pilot on the news last weekend suggesting
that the only way to prevent this in the future is to put traffic lights
(stop / go) on the end of every runway. I absolutely got the impression
that he was there to convince the public that it is almost impossible
for the pilots to get it right and the lack of the traffic signal was
the whole cause of the problem. Sort of the typical "not my fault" attitude.

If he thinks that is the only way, he is clueless.

Robert M. Gary wrote:

I heard some retired commuter pilot on the news last weekend suggesting
that the only way to prevent this in the future is to put traffic lights
(stop / go) on the end of every runway.


I saw this demoed somewhere (but I don't remember where). It was pretty
cool. There was a row of read lights across the taxiway access to the
runway until cleared for takeoff.

-Robert


That has been tried off and on for years, with less than great success.
It is a saturation job for someone in the tower to keep the system
working. Sooner or later, a wrong signal is sent.

-----Original Message-----
From: Sam Spade ]
Posted At: Saturday, September 02, 2006 4:03 AM
Posted To: rec.aviation.ifr
Conversation: Can EFIS / EFMS lead to removing basic safety checks?
Subject: Can EFIS / EFMS lead to removing basic safety checks?

Jim Carter wrote:


I heard some retired commuter pilot on the news last weekend
suggesting
that the only way to prevent this in the future is to put traffic
lights
(stop / go) on the end of every runway. I absolutely got the
impression
that he was there to convince the public that it is almost
impossible
for the pilots to get it right and the lack of the traffic signal
was
the whole cause of the problem. Sort of the typical "not my fault"
attitude.

If he thinks that is the only way, he is clueless.

My sentiments exactly Sam.

My question was more along the lines of new systems removing old safety
checks, but no one seems to be addressing that. Is there any physical
action that must be taken as an aircraft with and EFIS / EFMS moves into
position for takeoff to assure that the compass / gyro (or suitable
substitute) / display all agree on the runway heading? Could the modern
glass cockpits be setting us up for incidents or accidents because
insidious little actions we used to take with analog panels aren't
necessary any more?