MDW Overrun - SWA

This is all speculation, that is all true. Something that bugs me is
that
the ILS for 31C requires RVR of 4000 or 3/4 of mile visibility. The
METAR
from just before the accident pegged visibility at 1/2 mile. Seems to me
that the approach shouldn't have even started.

Well, for starters, prevailing visibility and a specific runway's RVR
can often differ by quite a bit. That's why RVR is controlling for an
airliner. It also changes minute by minute, and the hourly ATIS isn't
at all a good indicator of what the RVR was when that airplane landed.

Yep, thanks for that. The hourly METAR was:

KMDW 090053Z 10011KT 1/2SM SN FZFG BKN004 OVC014 M03/M05 A3006 RMK AO2
SLP196 R31C/4500FT SNINCR 1/10 P0000 T10331050 $

Showing the field visibilty as 1/2-mile and 31C's RVR as 4,500 feet -
greater than minimum.

The FAA accident report has the following for the weather:

0115 11007KT 1/2SM SN FZFG VV003 M04/M05 A3006 R31C/4500V500

This doesn't appear properly formatted, as with a V separator, it's supposed
to be minimum and maximum. It's possible that it's supposed to be a minimum
of 4,500 and a maximum of 5,000 feet, and the extra zero was dropped off.
Or it could be that visibility ranged from 500 feet to 4,500 feet. That I
find less likely.

It'll be interesting to get the CVR and ATC transcripts and find out what
the pilots were told.

Second, Southwest's 737-700 airplanes have a heads-up display that lets
them use 3000 RVR on that runway at MDW.

Interesting! Do you any additional info on that?

In article , Charles Oppermann
wrote:

The FAA accident report has the following for the weather:

0115 11007KT 1/2SM SN FZFG VV003 M04/M05 A3006 R31C/4500V500

This doesn't appear properly formatted, as with a V separator, it's supposed
to be minimum and maximum. It's possible that it's supposed to be a minimum
of 4,500 and a maximum of 5,000 feet, and the extra zero was dropped off.

That's incorrect -- it's not minimum to maximum. It's 4500, variable
to 500. In the ops specs for every airline operation with which I'm
familiar, including my current 121 airline, the "variable" portion is
advisory only. So as far as weather for starting the approach, it was
4500.

It'll be interesting to get the CVR and ATC transcripts and find out what
the pilots were told.

Yep. If the tower gave them a more up-to-date RVR (which is pretty
likely), that's controlling over the sequence weather you posted above.

Second, Southwest's 737-700 airplanes have a heads-up display that lets
them use 3000 RVR on that runway at MDW.

Interesting! Do you any additional info on that?

I don't have much info beyond that, specific to SWA. The HUD is an
option on the next-generation 737s, and many of SWA's are so-equipped.
It's a real safety enhancement in low visibility. (That should also
discredit the notion that the airline skimps on safety equipment -- it
doesn't.)

Here's a picture of it in one of their cockpits:
http://www.airliners.net/open.file/868375/L/

That's incorrect -- it's not minimum to maximum. It's 4500, variable
to 500. In the ops specs for every airline operation with which I'm
familiar, including my current 121 airline, the "variable" portion is
advisory only. So as far as weather for starting the approach, it was
4500.

Hmmm, I was going by the various METAR decoders I have and a look at the
FAA's Aviation Weather Services publication (AC 00-45E). A detailed
breakdown at the following link:
http://www.met.tamu.edu/class/METAR/metar-pg8-RVR.html

This is academic parsing, and may not reflect actual practice.

I don't have much info beyond that, specific to SWA. The HUD is an
option on the next-generation 737s, and many of SWA's are so-equipped.
It's a real safety enhancement in low visibility. (That should also
discredit the notion that the airline skimps on safety equipment -- it
doesn't.)
Here's a picture of it in one of their cockpits:
http://www.airliners.net/open.file/868375/L/

Very cool, thanks. Since it only exists on the captain's side, I wonder
what the CRM procedure is to shift roles if the first officer is the Pilot
Flying.

Thanks for the link.

On Mon, 12 Dec 2005 19:05:33 -0800, "Charles Oppermann"
wrote:

I don't have much info beyond that, specific to SWA. The HUD is an
option on the next-generation 737s, and many of SWA's are so-equipped.
It's a real safety enhancement in low visibility. (That should also
discredit the notion that the airline skimps on safety equipment -- it
doesn't.)
Here's a picture of it in one of their cockpits:
http://www.airliners.net/open.file/868375/L/

Very cool, thanks. Since it only exists on the captain's side, I wonder
what the CRM procedure is to shift roles if the first officer is the Pilot
Flying.

I think the OPSPEC generally requires the captain to handle landing if
the weather is that bad.