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SWA Safety ALERT RW 23 ILS KBUF

SEVEN

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Not sure if this has been posted yet.
Safety Alert issued to SWA Pilots regarding the ILS 23 KBUF


Safety Alert 2009-1
BUF ILS Hazard



SWAPA Pilots,

There is a potentially significant hazard concerning the ILS to runway 23 in BUF.

Information has been received indicating it is possible to obtain a significant nose pitch up, in some cases as much as 30 degrees, if the glide slope is allowed to capture before established on centerline. Pilots who are preparing to configure and land have the potential to experience abrupt pitch up, slow airspeed, and approach to stall if conditions present themselves in a certain manner.

This effect is the result of an earthen obstruction close enough to the ILS to affect the integrity of the glide slope signal. This has resulted in the issuance of an advisory given on ATIS which states that "the ILS Glide Slope for runway 23 is unusable beyond 5 degrees right of course."
When attempting to intercept the runway 23 ILS from right traffic, the ILS glide slope indication may read full deflection down. Just prior to intercept it may then move up in such as manner as to enable approach mode to capture in such a way as to result in a nose up pitch and loss of airspeed.

Southwest Airlines has issued a notice reading: "Until further notice, when executing the KBUF ILS/LOC Runway 23, DO NOT select Approach Mode until established on the localizer inbound."
This issue is being addressed on several levels in an attempt to address procedures, facilities, and communication regarding this matter. If you experience any issues related to this, please file an ASAP form and or call SWAPA Safety at SWAPA toll free.
 

glasspilot1

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This could be good information, however Colgan was turning on the LOC from left traffic, south of the localizer. But a APP mode GS capture and pitchup would explain a lot with this wreck.
 

enuffalready

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Frightening...late at night... slow... tired... pitch up 30 degrees..


sure would be nice if it stated, beware rapid pitch up-- versus--- unusable beyond 5 degrees...




Not sure if this has been posted yet.
Safety Alert issued to SWA Pilots regarding the ILS 23 KBUF


Safety Alert 2009-1
BUF ILS Hazard



SWAPA Pilots,

There is a potentially significant hazard concerning the ILS to runway 23 in BUF.

Information has been received indicating it is possible to obtain a significant nose pitch up, in some cases as much as 30 degrees, if the glide slope is allowed to capture before established on centerline. Pilots who are preparing to configure and land have the potential to experience abrupt pitch up, slow airspeed, and approach to stall if conditions present themselves in a certain manner.

This effect is the result of an earthen obstruction close enough to the ILS to affect the integrity of the glide slope signal. This has resulted in the issuance of an advisory given on ATIS which states that "the ILS Glide Slope for runway 23 is unusable beyond 5 degrees right of course."
When attempting to intercept the runway 23 ILS from right traffic, the ILS glide slope indication may read full deflection down. Just prior to intercept it may then move up in such as manner as to enable approach mode to capture in such a way as to result in a nose up pitch and loss of airspeed.

Southwest Airlines has issued a notice reading: "Until further notice, when executing the KBUF ILS/LOC Runway 23, DO NOT select Approach Mode until established on the localizer inbound."
This issue is being addressed on several levels in an attempt to address procedures, facilities, and communication regarding this matter. If you experience any issues related to this, please file an ASAP form and or call SWAPA Safety at SWAPA toll free.
 

DashTrash400

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Q400 flight director arms both LOC and GS when APP mode is selected, but GS mode will not capture until the LOC mode is already active. I never had a Q400 FD/AP inappropriately climb to intercept the glideslope, either.
 

BoilerUP

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Anybody verify that this is a real alert, and not some snarky, in poor taste attempt at humor?
 

atrdriver

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Q400 flight director arms both LOC and GS when APP mode is selected, but GS mode will not capture until the LOC mode is already active. I never had a Q400 FD/AP inappropriately climb to intercept the glideslope, either.

That can be said for all transport category autopilots. But on a 30 degree intercept the loc will begin it's capture about 2 dots out, sometimes a little more than that, and that enables the G/S to start it's capture. If there is really some earthbound obstruction causing a problem that would go a long way to explaining this.
 

WayBack

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I'd just like to thank the SWA Pilot Union on notifying us about this.
Wonder why ALPA can't get info out like this in a timely manner. I guess those who are still members, your dues don't cover releasing info like this.
 

N813CA

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I have had it happen twice going into LGA 22 in the last year in the CRJ. Just have to be ready for it and take over the airplane.
 

firstthird

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That can be said for all transport category autopilots.

not true, the 737 autopilot will most definitely capture the GS before being in VOR/LOC. although in this case I don't think it matters, as you pointed out.

If I'm reading this alert correctly, it basically says that your GS could attempt to capture the erroneous signal, giving very strange pitch excursions. so when it captures (before or after VORLOC captures) isn't really relevant if this 'bad' zone corresponds with the VORLOC window.
 

Abernathy

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Has happened to me once on the ATR, airplane pitched up quite abruptly as soon as the GS came alive and started climbing for it. Had I not noticed it and disc. the autopilot, it would have easily brought out the stick shaker. It was trimming quickly right before I disconnected it.

Happened once on the CRJ-200 as well. Weird as heck and I didn't understand why it would just randomly do that. Both times into ATL.
 

atrdriver

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Has happened to me once on the ATR, airplane pitched up quite abruptly as soon as the GS came alive and started climbing for it. Had I not noticed it and disc. the autopilot, it would have easily brought out the stick shaker. It was trimming quickly right before I disconnected it.

Happened once on the CRJ-200 as well. Weird as heck and I didn't understand why it would just randomly do that. Both times into ATL.

I had it a couple of times into ATL on the ATR as well. 27L if I remember right, before they built 10/28.
 

atrdriver

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not true, the 737 autopilot will most definitely capture the GS before being in VOR/LOC. although in this case I don't think it matters, as you pointed out.

From section 6.4 page 17 of the CAL 737 flight manual:

"Glideslope capture is inhibited prior to localizer capture."

It is true of all transport catagory aircraft because often times the G/S is unreliable more than 30 degrees or so off the loc, and often the mode is armed outside of that arc.
 

CRJ puppy

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Anybody verify that this is a real alert, and not some snarky, in poor taste attempt at humor?

It's real. I posted a comment the day after the accident on another thread about this but no one noticed. :(

Have been in VMC when the AP chased these erroneous signals. It's quite dramatic and you need to disconnect the autopilot quickly or doo doo would happen fast!

There is a notam about the GS being unusable x number of degrees of centerline, but no explanation as to why.
 

DBacks

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Does anyone know if radar recorded the aircraft climbing a few hundred feet before it plunged to earth? From what I have read the only radar returns were of the aircraft rapidly descending.
 

firstthird

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From section 6.4 page 17 of the CAL 737 flight manual:

"Glideslope capture is inhibited prior to localizer capture."

I'm sure your book says that. SWAs says something along the lines of "if you think that GS capture will occur prior to VORLOC capture, consider arming VORLOC instead of APP."

and, I've seen it happen. There are a lot of 737s out there and there are differences. Shoot, my squadron in the navy had 3, all delivered within a year of each other, and one would capture the GS first while the other two would not.
 

atrdriver

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I'm sure your book says that. SWAs says something along the lines of "if you think that GS capture will occur prior to VORLOC capture, consider arming VORLOC instead of APP."

and, I've seen it happen. There are a lot of 737s out there and there are differences. Shoot, my squadron in the navy had 3, all delivered within a year of each other, and one would capture the GS first while the other two would not.

Well, FWIW, I got into the habit of arming LOC only until it was captured, then arming the ILS because I had it bite me a couple of times while on the ATR.
 
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