Constant-rate descents on non-precision approaches

minitour said:
With all due respect, if you can't come up with (real quick in your head) speed (miles per minute), minutes from FAF to MAP (or PDP/VDP) and altitude to lose, and solve for X (rate of descent), you probably shouldn't be flying the instrument approach.

All of my instrument students are capable of doing it prior to checkride time. IMO, students should be required to show proficiency in constant rate NPAs at least one time on a checkride.

-mini
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It's not a matter of ability. Didn't say I could or couldn't do it. I was simply trying to imply that flying a 172 figuring out the math is very much akin to people who call center by saying with you. It's extraneous and not needed.
 
MikeD said:
Again, the two methods are techniques. Both acceptable techniques with their respective limitations and/or merits. Arguing which is better is again, like arguing whether coke or pepsi is better.
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Exactly! This goes right up there with do you do a procedure turn, pitch for airspeed or believe god created everything. For some reason this is another one of those topics that people come up with all sorts of justifications that their way is the only way and everyone else is right (not saying anyone is doing that in this thread...yet). If memory serves we had a thread just like this several months ago.
 
poser765 said:
Exactly! This goes right up there with do you do a procedure turn, pitch for airspeed or believe god created everything. For some reason this is another one of those topics that people come up with all sorts of justifications that their way is the only way and everyone else is right (not saying anyone is doing that in this thread...yet). If memory serves we had a thread just like this several months ago.
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FBO or Academy?
 
poser765 said:
It's not a matter of ability. Didn't say I could or couldn't do it. I was simply trying to imply that flying a 172 figuring out the math is very much akin to people who call center by saying with you. It's extraneous and not needed.
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We'll need to agree to disagree. :beer:
shdw said:
I bet you teach them to brief the approach before hand and not figure it out as they pass the fix though. ;) I think poser forgot that key step, do it early, not while flying the approach.
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Absolutely. The last time to be doing mental math is when you're flying a course, descent rate, ground speed and looking for a distance/time to expire, plus trying to find an airport. Get it done beforehand.

-mini
 
shdw said:
That is really interesting, do you have the study. I have googled for it and discovered this, which seems interesting but I am unsure if it is what you are referring to.

http://www.flightsafety.org/alar/alar_bn7-2-nonprecision.pdf
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That is one of the studies published. Think about it. What is a stabilized approach? And what type aircraft does it apply to? There is a propensity for a drift down of big jet terms and definitions to gen av airplanes which do not really apply. V1 for example.. there is no real V1 for small gen av airplanes. And there is no 'blue line' for jets.

You do what works and what is safe. And then you have to sell it to the consumer. The average gen-av guy/gal is not going to buy a CROD and for good reason. Their instructor has said get down to MDA and troll for the runway. It works at 80kts. It doesn't work for 130+kts. At 1 mile and 500ft, there is no way you are going to change config, drop 10-20kts, saw off a fist full of power and complete a 'stable approach'. Land? Maybe if the runway is long enough. Smart? Probably not. (one mans opinion).
 
Hmmm, interesting topic.

I'm not sure if it's considered "dive and drive," but my company's profile after the FAF while descending to MDA is 800-1000fpm with the gear down, flaps 30, 120 KIAS. It's a controlled descent that's specifically meant to get you down to MDA so that you can look for the runway prior to the VDP and MAP. I will add, however, that you do need to be careful with this technique. It requires a large amount of discipline and a strong scan to remain at the MDA until the VDP, even if you believe that you have the runway in sight beforehand. At night in low visibility, a road or row of lights on the ground can be very easily mistaken for the runway, even if the runway isn't yet in view. Corporate Airlines actually put a Jetstream 32 in at KIRK about 5 years back due to what I'm talking about. More information on this here: http://www.ntsb.gov/publictn/2006/AAR0601.htm

I should add that the 800-1000fpm stipulation that we have at my company approximates about a 4 degree descent rate, and usually gets you to the MDA right around (or slightly before) the VDP anyway. I'm not going to say that using a higher descent rate and "dive and drive" technique is outright dangerous, but I think some caution is needed.
 
I'm on board with OrangeAnchor with this one. Do what suits YOUR operation the best.

For C150J, Our operation actually has an OpSpec where we can build our own VNAV approach, with certain criteria not withstanding, and convert the MDA to a DH.

And for approaches we choose to "Dive and Drive" we round up to the nearest 100' above MDA (previous shop too), versus a constant descent approach that adds 50'.

Realistically, with a VNAV equipped aircraft (not sure if that applies to the new fancy GA airplanes too or not) you are flying ILS and non-ILS approaches.
 
Polar742 said:
I'm on board with OrangeAnchor with this one. Do what suits YOUR operation the best.

For C150J, Our operation actually has an OpSpec where we can build our own VNAV approach, with certain criteria not withstanding, and convert the MDA to a DH.
And for approaches we choose to "Dive and Drive" we round up to the nearest 100' above MDA (previous shop too), versus a constant descent approach that adds 50'.

Realistically, with a VNAV equipped aircraft (not sure if that applies to the new fancy GA airplanes too or not) you are flying ILS and non-ILS approaches.
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That's awesome, does it have to be based on a pre made approach, or can you TERPS it yourself, for operations in foreign countries.
 
ppragman said:
That's awesome, does it have to be based on a pre made approach, or can you TERPS it yourself, for operations in foreign countries.
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It's an overlay.

So, for example, we can turn an NDB approach into a VNAV, if it meets certain criteria.
 
minitour said:
We'll need to agree to disagree. :beer:



-mini
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I think that was sort of my point over all, mini. This is one of those topics that seems to have two camps that zealously stick with their technique. So, we can disagree, because neither one of us is really right but in our own way of flying. Does that make sense, or am I rambling?
 
poser765 said:
I think that was sort of my point over all, mini. This is one of those topics that seems to have two camps that zealously stick with their technique. So, we can disagree, because neither one of us is really right but in our own way of flying. Does that make sense, or am I rambling?
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I was referring to the "extraneous and not needed" part, but sure! :)

-mini
 
First, for airline ops, studies again showed that for MOST airline ops, the only time an aviator does a non-precision is once or twice a year in the sim. The study focused on the majors but for the most part, few actual NPAs and almost NONE to actual mins. And from my experience before retiring, it was true.

What I did see in the training dept was frequent mistakes including confusing a step down with the FAF. CLT used to have a VOR app to 36R and the Fort Mill VOR was a step down but quite a few crews mistook FML for the FAF and went to mins. It was a 'great mistake', one where you learn a lot but pay no penalty for the error. Anyway, crews would go to mins and I could then freeze the sim, lift the wx and they would be 400ft off the ground MILES from the runway. Unfreeze the sim and let them drive for a few minutes. It was frequently a very good learning event.

Having said that, the lessons I saw were
1) NPAs have less info and therefore require MORE attention to detail
2) NPAs usually have step downs that can easily be confused with the FAF
3) NPAs should be flown on autopilot to reduce workload
4) round MDAs up to the next 100ft. It is unlikely that 40-60ft is going to make a difference.

I am not trying to make NPAs into an abnormal but in airline ops, we just didn't do that many that often. They warrant a extra bit of attention if the last one you did was six months ago in the sim.
 
Orange Anchor,

Your post brought a thought to the mostly useless grey matter between my shoulders. After the synapses finally powered up, I thought about the Ron Brown accident.

Here you had an Air Force VIP squadron that had a boondoggled NDB approach.

Now, I take it into strong consideration that there is MUCH more training in the military than the civilian world. And the transport folks tend to have way more time actually flying as well. Yet this ended up in a crash on a basic non-precision approach.

Flying Tigers deal too. Yes, THAT Flying Tigers video that we see every year for CRM. Sitting around watching that video, one wonders what those guys were doing in the cockpit. However, a more thought out process leads us to realize that this was a highly experienced crew, and as Flying Tigers was a scheduled operation, that was not the first time they went into that airport.

The end of it all is the reality that the further we are removed from non-precisions (especially those of us on VNAV aircraft), the more dangerous they become.
 
ftyflyboy said:
If you are shooting the approach in IMC, the whole idea is to get as low as possible, as soon as possible. You want to clear the clouds and get a visual on the runway to ensure a landing.
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I don't like the idea of being at 600' 5 miles from the airport in a light single, either. MDA 1 mile from the MAP is what I aim for. My instructors have all come from the "dive and drive" school of thought on this however.

Given the fairly limited number of approaches I've flown at minimums, if the weather is really that bad, I'd be landing at a field with an ILS these days anyway.
 
Polar742 said:
It's an overlay.

So, for example, we can turn an NDB approach into a VNAV, if it meets certain criteria.
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So you can't go any lower, but you can be more stabilized on the approach. I guess that's good. Although, I do remember that step down fixes, and the like, make it easy to screw up an approach when you're going 180KIAS, so that'd be helpful.
 
drunkenbeagle said:
I don't like the idea of being at 600' 5 miles from the airport in a light single, either. MDA 1 mile from the MAP is what I aim for. My instructors have all come from the "dive and drive" school of thought on this however.

Given the fairly limited number of approaches I've flown at minimums, if the weather is really that bad, I'd be landing at a field with an ILS these days anyway.
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LPV rocks. Its like shooting an ILS to a gravel runway sometimes. They were just getting them going at ACE, and they were really cool.
 
ppragman said:
So you can't go any lower, but you can be more stabilized on the approach. I guess that's good. Although, I do remember that step down fixes, and the like, make it easy to screw up an approach when you're going 180KIAS, so that'd be helpful.
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No, we are able to change a MDA to a DA for a VNAV overlay. I forget the OpSpec number but it exists.

We train the VNAV, which inherently makes a CROD, and we are trained to CROD via VS mode, without the vertical guidance (although you can't really turn it off, so you fly the VPATH anyway.)

We can also opt to fly the approach as "Dive and Drive", and are trained to do so. The approach we train on is some boondoogle and really sucks, but you can get though it if you use proper crew management.

However, after comparing it to the regular non-ILS procedure, I really can't see a reason to Dive and Drive or CROD manually since we are required to use an MDA vs a DA.
 
drunkenbeagle said:
I don't like the idea of being at 600' 5 miles from the airport in a light single, either. MDA 1 mile from the MAP is what I aim for. My instructors have all come from the "dive and drive" school of thought on this however.

Given the fairly limited number of approaches I've flown at minimums, if the weather is really that bad, I'd be landing at a field with an ILS these days anyway.
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I did that all day yesterday, in varying conditions between 2 and 5 miles of vis.
 
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