ILS 26 at Lewiston ID, KLWS

[bbchien]

New approach for consideration!

Look at this plate. Where exactly is the miss? And, how do you fly the circling approach?

Interesting that the VOR 26 has a fly visual segment after the miss....

 

[SCCutler]

OK, I'll bite. MAP is the middle marker. Also, defined by reaching 200' (1638), needle centered, no ruway environment in sight.

And I guess that, if I want to fly the circle to land, I cannot descend below 1920 unless I am in a position to make a normal visual approach to land.

Am I dead?

 

[Fast n' Furious]

There's couple of these running around. Fly to DA of 1638 for the straight in. Just remember to decouple at 2320 MSL. Gotta stay on the GS to your circling MDA based on your aircraft category and continue to the MAP based on time. Penetrations in the FAC trap basically kill the LOC only mins as well as jack up the circling mins for all aircraft categories. Remember to decouple from the autopilot at 2320 feet MSL. Other than the fact that it's on the plate can you tell me why?

 

[Alan]

Good one. I can answer your questions, but why is the MQG 148 radial depicted?

[edit] Never mind, I looked at the Jepp and it's very clear there.

 

[Alan]

There's couple of these running around. Fly to DA of 1638 for the straight in. Just remember to decouple at 2320 MSL. Gotta stay on the GS to your circling MDA based on your aircraft category and continue to the MAP based on time. Penetrations in the FAC trap basically kill the LOC only mins as well as jack up the circling mins for all aircraft categories. Remember to decouple from the autopilot at 2320 feet MSL. Other than the fact that it's on the plate can you tell me why?

Ummm.... Note 1. Autopilot approaches not authorized below 2500'.

 

[Fast n' Furious]

Ummm.... Note 1. Autopilot approaches not authorized below 2500'.

Well you can't do an autopilot coupled approach below 2320 MSL but what I'm asking is do you know why these NOTAMs are done versus something like a restriction that would say glideslope unusable below 2320?

 

[bbchien]

What do you do when you lose the GS at 2100 feet MSL, and why is it so?

Hint: attached

 

[SCCutler]

OK, that was freaky. Where'd Dr. Bruce's latest post go?

*edit* Oh, I see, you are going Socratic on us. Good stuff!

Yes, I saw that the Jepp had it better depicted, reminds me that I need to make more money so I can use Jepps again.

 

[Fast n' Furious]

What do you do when you lose the GS at 2100 feet MSL, and why is it so?

Hint: attached

Doc. Huh? What GS are you losing on a VOR approach?

 

[bbchien]

Doc. Huh? What GS are you losing on a VOR approach?

OK. More simply put, why is there no Localizer approach associated with this ILS? Why can't you fly the localizer?

The hint is in the VOR 26 which come is 34 degrees to the north, and how its MAP is determined.

And I'll try again on the VOR approach link. I can't get it to work!

B.

 

[Fast n' Furious]

OK. More simply put, why is there no Localizer approach associated with this ILS? Why can't you fly the localizer?

The hint is in the VOR 26 which come is 34 degrees to the north, and how its MAP is determined.

And I'll try again on the VOR approach link. I can't get it to work!

B.

You can fly the localizer Bruce. But only after you decend on the glideslope to the appropriate circling MDA. Then continue on the LOC at MDA to the MAP which is the threshold based on time. As I mention above this is a very shrewd use of criteria by the procedure designer to get near LOC mins by using the 34:1 no penetration rule for an approach with a GS. The underlying terrain/obstacles will not support reasonable LOC mins but you can make an end run by using the 34:1 rule.

 

[SCCutler]

You lose the right to continue to descend on the approach at all, since the approach requires that you continue on the GS to DH whether you intend to land 26 or circle; but what hints do we pick up from the VOR approach?

Is the problem the proximity of 2000'+ terrain to the immediate left of the loc, such that a proper missed approach still requires that you overfly the field so you are assured adequate terrain separation on the left turn to MQG? IE, if you initiate a left turn for the missed when you lose the GS at 2100, you may turn left into rocky clouds?

But that still does not answer the "no coupled app below 2500," unless you are worried about an FD flying a coupled miss and hitting the terrain.

Educate me!

 

[wsuffa]

Interesting. The obstruction nearest the airport is clear on the NOS charts, but not so clear on Jepp. The hill near the OM is clearer on Jepp but less clear on NOS (it's there, but not as apparent). No dive-and-drive here.

The VOR approach needs to come in at an angle to avoid the hill, the altitude restriction is necessary to clear the close-in obstruction. That's also why the note that you must follow the GS on the circling approach until the MAP.

 

[Fast n' Furious]

You lose the right to continue to descend on the approach at all, since the approach requires that you continue on the GS to DH whether you intend to land 26 or circle; but what hints do we pick up from the VOR approach?

Is the problem the proximity of 2000'+ terrain to the immediate left of the loc, such that a proper missed approach still requires that you overfly the field so you are assured adequate terrain separation on the left turn to MQG? IE, if you initiate a left turn for the missed when you lose the GS at 2100, you may turn left into rocky clouds?

But that still does not answer the "no coupled app below 2500," unless you are worried about an FD flying a coupled miss and hitting the terrain.

Educate me!

If you are going to do a straight in here by all means please fly the LOC and GS to DA on 1638. If you are coupled to George on the approach please turn him off at 2320 because a reversal of trend in the glideslope is going to turn him off for you. If you are going to circle use the LOC and GS to the appropriate circling MDA for your airplane and then abandon the GS while maintaining MDA till you are in a position to land, or you execute the miss from the MAP. Which is your MDA at the threshold. Just use the glideslope to get to MDA, then just stay on the LOC to the MAP, or you manuver to land.

 

[SCCutler]

If you are going to do a straight in here by all means please fly the LOC and GS to DA on 1638. If you are coupled to George on the approach please turn him off at 2320 because a reversal of trend in the glideslope is going to turn him off for you. If you are going to circle use the LOC and GS to the appropriate circling MDA for your airplane and then abandon the GS while maintaining MDA till you are in a position to land, or you execute the miss from the MAP. Which is your MDA at the threshold. Just use the glideslope to get to MDA, then just stay on the LOC to the MAP, or you manuver to land.

I understand the minima for the approach, both straight-in and circling; what I do not understand is why there would be a "reversal of trend" which would decouple the A/P. I acknowledge that I have not flown any coupled approaches except playing; and have not learned enough about how coupled approaches work to comfortably use them yet.

*edit* Unless the G/S has a known characteristic of encountering a multipath bobble below 2500', something which would be sudden and significant enough that the machine would decouple, while a person would fly through to stable needle again?

 

[bbchien]

You can fly the localizer Bruce. But only after you decend on the glideslope to the appropriate circling MDA. Then continue on the LOC at MDA to the MAP which is the threshold based on time. As I mention above this is a very shrewd use of criteria by the procedure designer to get near LOC mins by using the 34:1 no penetration rule for an approach with a GS. The underlying terrain/obstacles will not support reasonable LOC mins but you can make an end run by using the 34:1 rule.

Ding, Ding, Ding...sort of! This designer was very very shrewd. There is an obstacle of some sort that intrudes under the GS (likely to the right of the Loc but who knows?), that the VOR approach has accomodated. To get margins around that obstacle, you are required to ride the GS on down to 1920. That suggests the obstacle is very near the bottom of the GS path.

I'm not sure that you can level out at 1920 on the localizer only if you dont' have the field. Certainly the airspace is protected (it's right above the GS) but they chose to depict NO LOC minimums....

But, the point is that you have an unusual GS without an authorized Localizer approach colocated with it. My students have a need to brief all the possibilities- I had one simpy respond, "why if I lost the GS I'd fly the localizer". That got a gentle tap on the head with the Enroute. "What localizer approach?" sez I. If you lose the GS inside the outer marker, you climb like hell on the localizer to the estimated (by time) MAP, climb and turn left and head to MQG at 5300.

So in briefing this approach, in the IFR gospel according to BC you have to ask the conditionals- what if?. And, notice JR- the coupled minimums are different on the Jepp chart (2500) vs. the NOS (2320). Error! Error!

It is clear that if one loses the GS at 2100 it's a miss. It's less clear after having ridden the GS down to 1920, and the GS is lost.....that it's authorized to continue to the airport by time at 1920 msl. I think I'd be climbing like heck.

Now, somebody tell me why the MM is not colocated with the ILS 26 MAP-with the needles centered, after the MM you still have 28 feet to descend or about 1000 feet to travel. I genuinely don't get this fine point. Any TERPS types out there?

 

[Fast n' Furious]

Interesting. The obstruction nearest the airport is clear on the NOS charts, but not so clear on Jepp. The hill near the OM is clearer on Jepp but less clear on NOS (it's there, but not as apparent). No dive-and-drive here.

The VOR approach needs to come in at an angle to avoid the hill, the altitude restriction is necessary to clear the close-in obstruction. That's also why the note that you must follow the GS on the circling approach until the MAP.

There is no problem with required obstacle clearance on this approach. The reason the FAC is a different radial from the intermediate is to take the airplane within 30 degrees of the primary runway for landing AND to take full credit for MALSR lighting which brings the flight vis down to .5 miles rather than 1 mile or none if you went beyond the 30 degrees. Beyond thirty and you take no lighting credit and there is no straight in mins authorized.

 

[Fast n' Furious]

I understand the minima for the approach, both straight-in and circling; what I do not understand is why there would be a "reversal of trend" which would decouple the A/P. I acknowledge that I have not flown any coupled approaches except playing; and have not learned enough about how coupled approaches work to comfortably use them yet.

*edit* Unless the G/S has a known characteristic of encountering a multipath bobble below 2500', something which would be sudden and significant enough that the machine would decouple, while a person would fly through to stable needle again?

The NOTAM is put in place by flight check. While on path the equipment in the airplane measures the actual quality of signal versus the theoretical. To put it very simply there are little bitty reversals of trend on every glideslopes just as there are flat spot, bends and general roughness. That misalignment is measured in microampreres and when there is a change of more than 25 mA over a very defined distance down becomes up or up becomes down. Your autopilot is designed to turn itself off when it senses this change rather than allowing a big pitch up, or down. Which could happen at a very bad time.

 

[bbchien]

Here's the real deal. I've only landed here once. Day IMC.

And I should say, there isn't a problem with clearance or there would be NO approach. The ILS has those margins. But the Localizer alone- wouldn't have reasonable mins. So, No Localizer.

Brief all the possibilities. There is NO LOCALIZER approach here. Most students are weak on the brief. Even weaker when "on the fly" briefing is required.

Good discussion here! ;-)

 

[Fast n' Furious]

Ding, Ding, Ding...sort of! This designer was very very shrewd. There is an obstacle of some sort that intrudes under the GS (likely to the right of the Loc but who knows?), that the VOR approach has accomodated. To get margins around that obstacle, you are required to ride the GS on down to 1920. That suggests the obstacle is very near the bottom of the GS path.

I'm not sure that you can level out at 1920 on the localizer only if you dont' have the field. Certainly the airspace is protected (it's right above the GS) but they chose to depict NO LOC minimums....

But, the point is that you have an unusual GS without an authorized Localizer approach colocated with it. My students have a need to brief all the possibilities- I had one simpy respond, "why if I lost the GS I'd fly the localizer". That got a gentle tap on the head with the Enroute. "What localizer approach?" sez I. If you lose the GS inside the outer marker, you climb like hell on the localizer to the estimated (by time) MAP, climb and turn left and head to MQG at 5300.

So in briefing this approach, in the IFR gospel according to BC you have to ask the conditionals- what if?. And, notice JR- the coupled minimums are different on the Jepp chart (2500) vs. the NOS (2320). Error! Error!

It is clear that if one loses the GS at 2100 it's a miss. It's less clear after having ridden the GS down to 1920, and the GS is lost.....that it's authorized to continue to the airport by time at 1920 msl. I think I'd be climbing like heck.

Now, somebody tell me why the MM is not colocated with the ILS 26 MAP-with the needles centered, after the MM you still have 28 feet to descend or about 1000 feet to travel. I genuinely don't get this fine point. Any TERPS types out there?

Yes I am a certified TERPS guys. I am also a flight check pilot. I know this particular approach very, very, very, well. As far as middle markers go they are positioned 3500 feet from the arrival end of the runway and a purely a range to runway aid. They serve no actual TERPS function and do not affect anyones minumums, ever. In fact they are being turned off faster than crap through a goose. The Canadians love them so much there aren't any in Canada. As far as the difference between the Jepp and the NACO chart NOTAM about coupled approaches, I don't know what Jepp is doing there because the flight checked value is 2320. I've checked it.

Well I hope this edit function works. The autopilot coupled NOTAM was changed on 12/03/04 during a flight check to a new altitude of 2500 feet for a reversal located at 3.00 from the threshold. Guess I've got something to chase around in the AM. Thanks!

 

[bbchien]

Tee hee. When I lived in Maine, a colleague of mine left his slider door ajar at his Blue Hill home. When he got back, there were four geese in the living room. You shoulda seen the poop damage. Jay_us. We shot a lot of goose that afternoon....

 

[Fast n' Furious]

Yeah, we'll you shoulda seen what was left of the leading edge of the left wing when I tried to fly my King Air through Mr. Goose at 249 knots. Good thing I wasn't above 10K or it coulda been a disaster.

 

[grattonja]

Interesting approach.

One thing that no one has discussed is the question of how you would circle for 8 or 11. The plate does not prohibit circling north of the airport, but I would not want to circle up there, with the obstacles, some only 300 feet below the circling MDA. In fact, according to AOPA's airport directory, traffic for both 8 and 11 is right hand pattern. I am thinking here that circle to land means breaking left to join a right downwind for 8. Under best circumstances anyway. Not sure, with the terrain and obstructions, that I would be very excited about a circling approach at all here. At least not with the amount of time I have.

Why does the plate not prohibit circling north of the runways?

Jim G

 

[Arnold]

Yes I am a certified TERPS guys. I am also a flight check pilot.

I always thought that would be a seriously cool job to have. My understanding is they are rarely available.

 

[Fast n' Furious]

Interesting approach.

One thing that no one has discussed is the question of how you would circle for 8 or 11. The plate does not prohibit circling north of the airport, but I would not want to circle up there, with the obstacles, some only 300 feet below the circling MDA. In fact, according to AOPA's airport directory, traffic for both 8 and 11 is right hand pattern. I am thinking here that circle to land means breaking left to join a right downwind for 8. Under best circumstances anyway. Not sure, with the terrain and obstructions, that I would be very excited about a circling approach at all here. At least not with the amount of time I have.

Why does not plate not prohibit circling north of the runways?

Jim G

300 feet of Required Obstacle Clearance (ROC) is the standard for a circling approach. The controlling obstacle is coded a 1A which allows an unadjusted ROC of 300 feet to be used. Good think you always check your altimeter before an approach, huh?

 

[Fast n' Furious]

I always thought that would be a seriously cool job to have. My understanding is they are rarely available.

It's a great job. Lots to do. Lots to learn. Given the state of the aviation industry today, I'm very happy where I am.

 

[grattonja]

300 feet of Required Obstacle Clearance (ROC) is the standard for a circling approach. The controlling obstacle is coded a 1A which allows an unadjusted ROC of 300 feet to be used. Good think you always check your altimeter before an approach, huh?

This approach is certainly an excellent reminder to do just that.

Jim G

 

[Ghery]

Note a few items about the terrain around KLWS. It is on a bluff overlooking the town and the Snake and Clearwater Rivers. River elevation is about 730 MSL (it is backed up by Lower Granite Lock and Dam and the road across the top of the dam is 748 MSL). I know, I helped build it in 1974 and 1975. Probably still have some of the drawings at home somewhere. The terrain just north of the river rises to around 2500 MSL, with higher obstructions. And, it rises sharply.

Wish I had a photo of KLWS from the air. Flew from KPUW (2550 MSL) to KLWS on a Horizon Air Dash 8 once. Took off on rwy 5, did about a 270 to the left, cleared the Snake River breaks and dove for the field. He was finishing his turn to final as he reduced his rate of decent to intercept the glide slope. They typically fly that segment VFR if conditions permit.

 

[bbchien]

Mr. Goose unmade my day one afternoon in Arizona in a Navajo. The right cowling peeled back, the drag was unbelievable, the vibration caused us to stow the engine, we couldn't maintain altitude, we limped into PRC.

That was 180 knots.

 

[Fast n' Furious]

The goose was bad enough. Did I mention the deer? I didn't mention the deer did I. Hey, howsabout you post up the LDA RWY 6 at KROA. That little nightmare ought to get some folks to start thinking. Is it precision, non precision, what?

 

[RobertGerace]

Bruce...thanks...this is exactly what the, uh, Doctor ordered!

I caught a cold and am in a bit of a fog...but learning nonetheless!!

I am NOT safe and self-grounded tomorrow...sigh...but that will give me the chance to read this thread a few more times

 

[bbchien]

The goose was bad enough. Did I mention the deer? I didn't mention the deer did I. Hey, howsabout you post up the LDA RWY 6 at KROA. That little nightmare ought to get some folks to start thinking. Is it precision, non precision, what?

I haven't looked at this one but to scan it. It's presented for everyone to think about.....

And check out this link. Not a Deer, but two HORSES. http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001213X28365&key=1
These were guys I knew with Guardian Ambulance Co. It's wild out there.

JR, you lead this time...

 

[bbchien]

Hmmmn. No takers.

Look at the Length of the GS and actually calculate the angle; then look at the gradient outside of Ramke.

 

[wsuffa]

I've flown the one at Roanoke. And ridden it in a commercial airliner many times (ROA is the closest airport w/commercial service to my undergraduate school).

The winds at ROA can get squirrely close to the ground - we hit windshear one night on the ILS33 as we crossed Hershberger Road (at the MM), dropping one wing about 10 feet. The pax gave the captain a round of applause when he landed safely. That was a Piedmont 737.

Note the minimums. Even the ILS33 will only get you 500' AGL.

Nighttime takeoffs are prohibited on 33 due to terrain. Nighttime landings prohibited on 15 due to terrain. Those are clues not on the NOS charts (Don't know about Jepp - Bruce does the ILS 33 Jepp show the restriction?)

 

[wsuffa]

A couple of other airports worth looking at the approaches....

KTRI (both ILS approaches)

KEKN - where one of the GPS approaches will get you much lower than the LDA-C.

 

[gismo]

Coming late to this party, I enjoyed reading all the ideas posted so far. I do have a couple questions of my own WRT final course alignment. First, why don't approach charts show the actual runway heading so it can be compared with the approach course. It seems to me this would be very useful information. On the LWS VOR 26 there appears to be a 17-18 degree difference given the 259 degree course on the ILS to the same runway yet nothing on the VOR plate shows this very well. In fact the arrow on the airport diagram looks perfectly aligned with the runway depiction. And on the ROA LDA-6 there's a note about the LDA being offset from the runway but again there is nothing to indicate what that offset is. Contientous pilots want to know!

I also wonder why there isn't a stepdown fix that would allow a LOC approach to runway 26 using the DME distance or radial from the VOR? Is it because the descent gradient would be too high?

Oh, and what fly visual on the miss? I don't see one.

 

[RobertGerace]

Oh, and what fly visual on the miss? I don't see one.

Something's been nagging at me for 24 hours....this is it! Thanks, Lance...I'm looking for that answer as well.

 

[bbchien]

Something's been nagging at me for 24 hours....this is it! Thanks, Lance...I'm looking for that answer as well.

Lance and Bob, my bad! I just quickly scanned the VOR chart and the way it final segment is depicted made me think that the earlier DME fix was the miss, not the 0.5 fix from the runway threshold.....sigh.

I'll post Bill's suggested approach images on another string for discussion of those approaches....

Bruce

 

[wsuffa]

Coming late to this party, I enjoyed reading all the ideas posted so far. I do have a couple questions of my own WRT final course alignment. First, why don't approach charts show the actual runway heading so it can be compared with the approach course. It seems to me this would be very useful information. On the LWS VOR 26 there appears to be a 17-18 degree difference given the 259 degree course on the ILS to the same runway yet nothing on the VOR plate shows this very well. In fact the arrow on the airport diagram looks perfectly aligned with the runway depiction. And on the ROA LDA-6 there's a note about the LDA being offset from the runway but again there is nothing to indicate what that offset is. Contientous pilots want to know!

I also wonder why there isn't a stepdown fix that would allow a LOC approach to runway 26 using the DME distance or radial from the VOR? Is it because the descent gradient would be too high?

Oh, and what fly visual on the miss? I don't see one.

Lance, on the Jepp ROA LDA 6 approach, the offset is shown. It shows Rwy centerline 058 and a LOC course 070 (then again, it also says 15 deg. offset).

 

[wsuffa]

And to add a note on the ROA LDA 6, the NOS chart shows the 070 course for the LOC, but you have to go to the airport diagram to get the runway orientation (057).

Point in favor of Jepp