If you HAVE to shoot an approach, would you choose an ILS or an LPV?

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Gubbins

Ejection Handle Pulled
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Here is a scenario...

You're en route to an airport and you've been a bad boy or girl and didn't plan your fuel properly. You're arriving at the airport with 5-10 minutes of fuel remaining. The weather has changed a lot from what you were expecting and is now below minimums. Not only is it below minimums, it is below 50 feet with a 1/4 mile visibility There is no other alternative, you cannot go anywhere else. So you shoot the approach just in case the weather report is wrong, but sadly no you have to go missed when you don't see the runway at the bottom. As you're doing the missed the engines sputters and you change tanks. The awful realization comes over you that you have only one more chance. The next one you have to keep on going down to the runway. There is no other alternative other than crashing elsewhere away from the airport.

So I've now set up the scenario for this bonehead. No fuel and you've got to do an approach down to the ground in fog basically. No missed as an option. There are two approaches. One is an ILS with a 200 foot minimum, the other is an LPV with a 250 foot minimum. Which one do you pick and why?
 
Since I've already made so many bad decisions to get to this point, what's one more?

Prolly choose the one that will give me the most line to the runway from where I a right now.
 
With 5 to 10 min of fuel I'm not going missed. I'm flying the ILS (not LPV) to the runway under emergency authority.
 
Prolly depends on where I am. Some localizers have weird bends in them. Bends probably isn't the right word but sometimes the radio beam is not quite straight in places. GPS is pretty solid unless you're near one of the jamming test sites. I've heard people say they'd trust GPS down to the ground.

Either way I'd prolly finally be happy that I went for the synthetic vision upgrade on the Aspen...
 
I'd choose the ILS if they had one, LPV if not, and the VOR if that wasn't available. If you've screwed yourself that bad, any approach with fuel stands a better chance than running out in flight without an approach.
 
I'd use the one with the closer FAF. If it's the same, the ILS. 'Cause the GPS can back up the ILS (remember, emergency authority, so having the CDI on GPS is OK if it doesn't work on VLOC), but not vice-versa.

Precision is nearly identical even if the FAA likes to call LPVs "non precision."

And of course fly the approach clean at best glide (except for gear on a retract), with the mixture leaned.

The right answer is to have some reserve and just not get backed into such a lousy corner.
 
Clark1961 said:
Prolly depends on where I am. Some localizers have weird bends in them. Bends probably isn't the right word but sometimes the radio beam is not quite straight in places. GPS is pretty solid unless you're near one of the jamming test sites. I've heard people say they'd trust GPS down to the ground.

Either way I'd prolly finally be happy that I went for the synthetic vision upgrade on the Aspen...
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Yes I'm with you for two reasons:

First, I've flown an LPV approach down to the ground... I had foggles on and I was with a very experienced and nationally known instructor. His instructions to me were very simple: He told me to ONLY look at the Flight Director (don't follow the glide slope or needle) and he said "I want you to use both hands and RELIGIOUSLY follow the Flight Director like your life depends on it, I'll tell you when you can look up". I did that and was shocked when he told me I could look up. I was literally over the runway maybe 20 feet above. I landed it. He told me to always take the LPV in this situation.

Second reason is just yesterday I had to shoot an ILS approach to minimums in actual. I let the autopilot do it and it had the needle perfectly centered. When I finally saw the runway I was offset. Not by much and I easily completed the landing but even so not very impressive and not very confidence inspiring!

So in that scenario I outlined above, I'm taking the LPV.
 
Definitely the LPV.
It is not sensitive to ground vehicle traffic or snow drifts or any other ground based error source. It generally feels smoother, more solid and more accurate on short final, although I can't swear that's not in my head. The 250 vs. 200 minimum in the OP's scenario is very likely some bureaucratic minutia that I wouldn't worry about in an emergency.
 
Having flown both I would do whatever was available. I prefer the LPV as for some reason the Cirrus loves to float around the loc even with the GFC 700... of course they say nuthin wrong with it but that's another discussion. The LPV on the other hand is dead on.
 
I like the LPV because it's less reconfiguring from GPS enroute and it's very capabible.
 
Fly over airport and pull the chute.
 
LPV - its much more stable all the way to the ground. It will fly you right into the 1000' markers if you let it.
 
SethV said:
LPV - its much more stable all the way to the ground. It will fly you right into the 1000' markers if you let it.
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I did that the other day. The Autoland on the Cirrus really sucks.
 
EminiTrader said:
Yaeh not my first choice. Us Cirrus guys call that the ownership transfer handle.. and I'm not quite ready for that :)
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If I was in an SR-22 with 50' ceilings and 5 minutes of fuel, the deciding factor for me would be how the avionics have been behaving. The chute would be an option I would consider. Never try to save hardware by risking soft tissue.
 
I'd go with the Lpv. More comfortable in my aircraft,with the LPV.
 
OkieAviator said:
Fly over airport and pull the chute.
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Was flying with someone who had all cylindars changed in his 20. While we were flying he started touching the handle. Told him if he wanted to pull the chute, should have done it BEFORE he changed all the cylinders.....

However back to topic.....in a Cirrus consider CAPS depending on circumstances. If avionics were pristine, I would probably do an LPV, if a coupled approach down to the ground was not possible. But this decision is something I need to investigate as you got me thinking. In either event I would declare an emergency.
 
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When / if I have to shoot an approach, I take whatever is available that will get me there. As for 5-10 minutes' fuel, never gonna happen. I follow the Golden Hour rule,and have so far not landed with less than 12 gallons (which is good for 1:20 at cruise settings, longer at approach speeds), and that was 4:40 after departure.

If you can't commit to always landing with an hours' fuel in your tanks, one day you will find yourself an unplanned glider pilot,with too much air in your fuel tanks.

Be safe out there!
 
With an estimated "5 to 10 minutes of fuel remaining" on the first go 'round, I would have already declared an emergency, asked for vectors to final for the ILS and either made it to the bar to toast my ticket farewell or made to the smok'n hole that was waiting for me.

I recently read a book in which the author claimed that as a junior first officer, he'd had a captain show him that it was completely possible to hand-fly a DC-10 to a (very near) 0-0 landing. He said it was something that never should have been done. But, the experience saved his bacon later on in his career.
 
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wilkersk said:
...I recently read a book in which the author claimed that as a junior first officer, he'd had a captain show him that it was completely possible to hand-fly a DC-10 to a (very near) 0-0 landing. He said it was something that never should have been done. But, the experience saved his bacon later on in his career.
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Thirty years ago I flew MU-2s for an air ambulance outfit out west. Our check airman made us hand-fly an ILS to touchdown every 6 months. It was actually pretty good training. (In the MU-2 you'd fly the entire approach and landing at flaps 20. MU-2s aren't known for their "roll-it-on" landings and the resulting landing wasn't much different from a normal landing. :D) In later years, I would have the sim instructors at FSI and CAE dial the sims down as low as could that would allow a hand-flown approach to touchdown. (I was told that it wouldn't work if they dialed in 0/0. The last sim required 50' and 1/16th of a mile if I recall correctly.) It's good practice and nice to have done it a time or two just in case it ever became necessary to do.

I've only had one experience where I consider that my training had paid off for me. Several years ago I was giving some instrument dual in a Cessna 172. We were on a combination night, IFR, "round-robin" XC training flight. The "out" part of the trip was uneventful. The weather was bang on the forecast - 4,000' ceilings with good visibility beneath, perfect conditions to allow an instrument student to get his first bit of actual.

The "back" part of the trip was another story. An unforecast winter squall developed and moved across our home airport and every possible alternate for about 100 miles. Ceilings and visibilities were running around 400' to 500' and 1/2 to 1 mile in blowing snow. Additionally, there was reported light icing.

Initially, I wasn't too concerned, it would be a good experience for the student to see just how quickly things can go "south" on you in spite of all the planning you do. (Sometimes Mother Nature just flat refuses to read the weather forecasts.) By the time we got to our home airport, the weather had dropped below the minimums for the VOR approach so we decided to go to our alternate which had an ILS. We had started to pick up a trace of ice, but it was only about 15 minutes to our filed alternate so I wasn't too concerned. Again, I felt that this could turn out to be some very good experience for the student.

As we diverted to the alternate the vacuum failure light on the instrument panel illuminated. That was no bueno and it was precisely not the time that I wanted to have deal with a vacuum failure. My student did a good job of partial panel flying, but after several minutes it started to get to him and he began to lose it. At that point, I took the airplane back and was flying "cross panel" partial panel. The winds started to pick up and the ride went from occasional light chop to light to moderate turbulence and the whiskey compass was all but unusable. At that point, I declared an emergency. What had started out a routine training flight with a couple of easily handled "issues" had turned into something altogether different.

As we weighed our options, it became apparent that the weather was going to get worse before it got better and we didn't have much more than the legally required fuel - waiting out the squall line in a holding pattern wasn't an option, besides we had started to pick up a bit more ice. I decided that we needed to get on the ground as soon as possible - the weather was at minimums for the ILS. I tried flying the first approach, but with the turbulence and the whiskey compass dancing around I couldn't keep on a heading that allowed me to track the localizer. Basically all I had was the electric turn coordinator. I missed that approach and went around for another attempt. This time we had approach control vector us to the inner marker and I descended on the glideslope. It was just a matter of doing what I had been trained to do. They were calling 200' and an RVR of 1600 when the runway lights came into view and we were able to land. I was glad that check airman made us do some hand-flown ILSes to touchdown. it's just another tool to have in your tool kit.
 
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mscard88 said:
request a PAR, takes you right to the ground :D
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LPV and ILS will take you right to the ground too...

I've done exactly one (practice) PAR approach. I suspect that is one more than most instrument pilots. If that's your only option, go for it. But out of fuel with weather below minimums is maybe not the best time to try something new if you don't have to.

Of course if you get an option to practice a PAR approach in better circumstances, it's a fun experience. I wish there was one closer to me that I could take people to.
 
\__[Ô]__/;1927744 said:
LPV and ILS will take you right to the ground too...

I've done exactly one (practice) PAR approach. I suspect that is one more than most instrument pilots. If that's your only option, go for it. But out of fuel with weather below minimums is maybe not the best time to try something new if you don't have to.

Of course if you get an option to practice a PAR approach in better circumstances, it's a fun experience. I wish there was one closer to me that I could take people to.
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A PAR is only as good as the controller and pilot combo. It didn't save Lex LaFon at Fallon.

I would fly the needles on an ILS or LPV before I'd fly a PAR to the ground.
 
Declare emergency, ILS or LPV (don't care, whichever is more direct), request lights on high (and since it's ILS there should be good approach lights), autopilot, and synthetic vision would be a good combo. If I had a chute and I wasn't certain I had enough fuel for the approach, I'd probably have to pull the handle.

However, I reject the premise. I would have stopped two hours prior to fuel up. :thumbsup:
 
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I ran PARs when I was an USAF controller. DH was 100' but we continued giving GS and azimuth info all the way down. I didn't work this flight but 5 F5s (Agressor Sqdn) went missed approach and immediately declared an fuel emergency. Approach vectored the flight in tight turning them onto a 4-5 mile PAR final. I happened to be in the tower where there were 3 parallel runways. Out of the fog came the F5s, actually landing on each runway safely.
 
Fearless Tower said:
A PAR is only as good as the controller and pilot combo. It didn't save Lex LaFon at Fallon.
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I didn't know about this accident. Thanks for the info that was an interesting read.

http://www.ntsb.gov/_layouts/ntsb.a...b534-43e4-813c-96b06cd26d54&pgno=2&pgsize=200

Note that one of the comments made was that he should have ejected. That was an option that he had in this case that he never used. Similarly, if you have a chute, I would say try the approach but don't go below minimums. In that case, try it then go missed and once at a safe altitude, pull the damn chute. Or eject if that is an option. Human life is worth more than ego and a lump of metal. I don't fly a plane with a chute but heck yes I'd use it in this case.
 
Gubbins said:
I didn't know about this accident. Thanks for the info that was an interesting read.

http://www.ntsb.gov/_layouts/ntsb.a...b534-43e4-813c-96b06cd26d54&pgno=2&pgsize=200

Note that one of the comments made was that he should have ejected. That was an option that he had in this case that he never used. Similarly, if you have a chute, I would say try the approach but don't go below minimums. In that case, try it then go missed and once at a safe altitude, pull the damn chute. Or eject if that is an option. Human life is worth more than ego and a lump of metal. I don't fly a plane with a chute but heck yes I'd use it in this case.
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Ejection wouldn't have helped. With those surface winds, ejection was not considered survivable - you'd likely be dragged to death before you could release the chute. Lex knew that and had discussed it in his blogs prior to the accident. Normally, had the winds been accurately forecasted, they never would have launched for a training flight.
 
Fearless Tower said:
Ejection wouldn't have helped. With those surface winds, ejection was not considered survivable - you'd likely be dragged to death before you could release the chute.
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Maybe. But seriously if you had to choose between being dragged by 35 knots winds versus impacting the ground at 250 knots or more you would choose the latter? The first case is probably a bad situation (you would know more than me) but even so is probably be more survivable than the second.
 
Gubbins said:
Maybe. But seriously if you had to choose between being dragged by 35 knots winds versus impacting the ground at 250 knots or more you would choose the latter? The first case is probably a bad situation (you would know more than me) but even so is probably be more survivable than the second.
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He didn't impact the ground at 250kts. He put the aircraft down nice and level on the field and ran into a building.

In retrospect, he would have been better off diverting to RNO and flying the ILS to the ground, but I think he let the controllers push him into a corner.
 
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Neither. Find the nearest road and land on it, gear up of course and brag to my friends on national television about the landing and how the plane just ran out of fuel despite the 30 seconds of planning I did.

OR..LPV :) I like GPS approaches a bit more for the reasons everyone already stated. However, I might also setup the localizer on my second VOR as a backup just in case something wonky went wrong on the way in.
 
Interesting folks are choosing a GPS over an ILS to shoot a zero zero approach to the pavement. I assume y'all know the rnp for your plane in appch phase of a GPS and have compared that to 1 dot deviation of a LOC needle at say 5,000 feet from the antenna?

Here's another way to look at it. All those airliners with full autoland....do you suppose they are authorized to do it with GPS or ILS or both? I've never heard of autoland using GPS and I suppose there is a reason that relates to rnp.


Guess my point is I think it'd be foolish to skip the ILS in favor of a LPV to drive it to the runway.
 
Captain said:
Here's another way to look at it. All those airliners with full autoland....do you suppose they are authorized to do it with GPS or ILS or both? I've never heard of autoland using GPS and I suppose there is a reason that relates to rnp.


Guess my point is I think it'd be foolish to skip the ILS in favor of a LPV to drive it to the runway.
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Well I'm not flying an airliner with Cat III ILS equipment at an airport with the corresponding approach that has been checked to that level... So not quite an apples to apples comparison.

In your case, yes I'd use the ILS autoland :lol:
 
Captain said:
Interesting folks are choosing a GPS over an ILS to shoot a zero zero approach to the pavement. I assume y'all know the rnp for your plane in appch phase of a GPS and have compared that to 1 dot deviation of a LOC needle at say 5,000 feet from the antenna?

Here's another way to look at it. All those airliners with full autoland....do you suppose they are authorized to do it with GPS or ILS or both? I've never heard of autoland using GPS and I suppose there is a reason that relates to rnp.


Guess my point is I think it'd be foolish to skip the ILS in favor of a LPV to drive it to the runway.
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RNP is just bureaucratic nonsense created by people who don't fly the system.
My WAAS GPS gives me accuracy down to a couple of feet, and that's all I need in an emergency.
 
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Gubbins said:
Well I'm not flying an airliner with Cat III ILS equipment at an airport with the corresponding approach that has been checked to that level... So not quite an apples to apples comparison.

In your case, yes I'd use the ILS autoland :lol:
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I wasn't suggesting anyone here is. What I'm pointing out is an ILS has a tighter deviation than GPS....even GPS with WAAS. It proven by the lower DA's published. While an LPV can go to a minimum 200' I believe which is the same as a CAT I ILS the beam is the same for a CAT I and a CAT III LOC and GS.

With that in mind I'm having a hard time justifying in my mind selecting a GPS approach over an ILS with the intention of driving it into the runway. Honestly, both would probably hit the runway....I'm just thinking the ILS would have better odds.

It's a hypothetical anyway...none of us (with any luck) are going to actually be in this situation.
 
Captain said:
Interesting folks are choosing a GPS over an ILS to shoot a zero zero approach to the pavement. I assume y'all know the rnp for your plane in appch phase of a GPS and have compared that to 1 dot deviation of a LOC needle at say 5,000 feet from the antenna?



Here's another way to look at it. All those airliners with full autoland....do you suppose they are authorized to do it with GPS or ILS or both? I've never heard of autoland using GPS and I suppose there is a reason that relates to rnp.





Guess my point is I think it'd be foolish to skip the ILS in favor of a LPV to drive it to the runway.
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That was my initial thought, although seeing as I just got my first WAAS GPS two months ago, I will confess to being a bit of an LPV noob.
 
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