There's nothing wrong with Dive and Drive

[3WE]

...If you level off at minimums and without seing the runway yet, chances are that you won't see it or...

OK, IT'S BEEN A FEW YEARS, BUT SOMEWHERE I SAW A WRITE UP AND DRAWING SAYING THAT IT'S BETTER TO "DIVE HARD" AND LEVEL OFF.

The drawing and write up suggested that if the clouds were in any way broken, you had an increased chance of finding a hole while flying along at the minimums, and then be able to succesfully land visually and legally.

However, if you do an "even glidepath" and the MAP is in a cloud instead of one of the breaks- then your only choice is go around.

I belive this was in some instrument training book- maybe even the FAA one...

I will see if I can find it.

(By the way- please know that the wording here emphasizes some stuff to make a point and overlooks some other important nuances...please just consider that there was a reference that said it was better to descend a little faster and then fly level longer, as opposed to arrving at the MAP and Minimum altitude at about the same time.)

[3WE]

...One of the most fun (and yes, I do mean that literally) "dive and drive" approaches I've shot during my career is the PDX Localizer 21. I did this several times in the Jetstream when I had no autopilot or flight director and LNAV/VNAV were strange, foreign concepts. ...Now throw a 20-30 knot wind coming straight across that hill and enjoy the yahoo ride as you have to poke the nose down to counteract the updraft. Also, note the 3.6 degree glide path to get to the runway. Lots of fun!

Good God Snyder...not only do you subject your passengers to the nasty noisy cramped Jetstream, the trip-spar in the middle of the cabin and it's nasty wallowing yawing ride in turbulence, you endanger them by doing a challenging step-down approach in a commercial airplane lacks all sorts of standard electronic helpers, including the ability to generate a consistent glidepath!

[Gabriel]

Some dude named Gabriel posted a graph showing a generally straight line for the final 6 miles- initially a little high- but finishing a bit low as compared to the ideal glidepath.

a- That "generally straight line for the final 6 miles" is made of just three points: The first two are flightaware, and the last one is the impact point calculated as 0.8NM from the threshold and the elevation obtained from Google Earth at that point. As you see, this is not very accurate. Especially not the last seconds where the sink rate sounded twice and then stopped, indicating a reduction of the VS.
b- You've insinuated that UPS was following an FMS-generated GS. That's what I'm asking how do you know.

[Gabriel]

Look, I'm not saying dive and drive is absolutely unsafe. I'm saying it has a significantly higher workload and risk factor than constant rate approaches. For that reason alone, not to mention the near-universal availability of vnav (either as delivered or as upgraded), I think they should be forbidden in commercial aviation.

Evan, I agree that step-down approaches are more high-workload, offer more opportunities for mistakes, and are hence involves more risks than an ILS or ILS-like approach. But let me spit a bunch of random thoughts (or not so random maybe)

ILS approaches in low IMC are much more dangerous than in VMC. So if the realtive safety is a factor, then let's forbid ILS in IMC.

Among all the things we criticized about the Polish AF-1, I don't remember that flying a step-down approach was one of them. That accident would probably not happened with an ILS-like approach.

I don't know if I'd go as far as forbidding step-downs.

I know that some airlines forbid the step-down approaches. They also forbid circle-to-land and landings in runways with no PAPI or VASI. Does this save lives? Probably. Is that a good policy? I have doubts... If we want pilots that are great monitoring the automation in straight-in approaches to runways with ILS and PAPI, probably it is. The problem arises when you need a REAL pilot.}

I concede that heavy reliance in top-notch automation and very restrictive procedures probably save more lives that lack of a good pilot when you really need one. And I think that this is part (and not a small one) of the reason why regional aviation jets have such a good safety record. But that's for another thread.

[3WE]

...You've insinuated that UPS was following an FMS-generated GS. That's what I'm asking how do you know.

1) Look at the two words I bolded and remember that this is a strange little aviation discussion forum full of parlour talking ass hats. Insinuation is rampant, knowledge less so.

2) Ok, your nice line comes from three unconfirmed and speculative datapoints- thanks for that reminder and clarification...yeah, questionable.

On the other hand, a big ole A 300 with Airbus-think-for-the-pilot-to-hell-with-traditional-behavior design with top of the line fancy computerization...... I go back to my earlier comment to Snyder asking if the big-iron world" isn't 99% FMS-generated glidepaths. This is not a Jetstream 31.

I don't know that it's an FMS generated glideslope, but I'll bet one of my books of expired approach plates that I pulled out of a trash can in a pilots lounge it was.

[snydersnapshots]

Good God Snyder...not only do you subject your passengers to the nasty noisy cramped Jetstream, the trip-spar in the middle of the cabin and it's nasty wallowing yawing ride in turbulence, you endanger them by doing a challenging step-down approach in a commercial airplane lacks all sorts of standard electronic helpers, including the ability to generate a consistent glidepath!

HEY! THEY PAID FOR A RIDE AND, BY GOD, THEY GOT ONE!!!

[snydersnapshots]

O
However, if you do an "even glidepath" and the MAP is in a cloud instead of one of the breaks- then your only choice is go around.

I know what you're saying--if you get down early and see the runway or you can start down, but when all is said and done, if you can't see the airport at the MDA, you shoot the missed regardless of how you got to the MDA. I remember a time when I shot the VOR/DME C at Wenatchee, WA. I broke out and saw the ground just fine, but couldn't find the airport even though I'd been in there 50 times or more. As you can see...EAT is not a place to dink around looking for an airport. Shot the missed and headed back to SEA... I've gotta say though, the VOR/DME C into EAT was another fun approach to shoot. And the apple milkshakes at the end of it were fantastic (those were the days when I could indulge in such things without gaining ten pounds).

[snydersnapshots]

On the other hand, a big ole A 300 with Airbus-think-for-the-pilot-to-hell-with-traditional-behavior design with top of the line fancy computerization...... I go back to my earlier comment to Snyder asking if the big-iron world" isn't 99% FMS-generated glidepaths. This is not a Jetstream 31.

Actually, probably 99% of our approaches involve vectors to an ILS with a traditional glideslope--even in visual conditions. Mind you, this has been my experience over the past several years, but I remember Dad talking about that 26 years ago when Western, whom he flew for, merged with Delta. The Delta guys were not as comfortable as the Western guys with approaches that didn't end with vectors to an ILS. It's not that the Delta guys were any better or worse than the Western pilots, it's just that the Western guys flew into many places where there was no radar and all they had were non-precision approaches. And this was before LNAV/VNAV approaches were even thought of.

I remember a story Dad told about having a Delta guy on the jumpseat going into Birmingham--the guy was extremely worried about the terrain around the airport (and we now know why). Dad and his FO, another Western guy, weren't too concerned because they were comfortable flying non-precision approaches around terrain. Dad just handed the guy the plate for the ILS at Butte, Montana and said "here, look at this one." All he heard from the jumpseat was "HOLY $#!T!"

[3WE]

I know what you're saying--if you get down early and see the runway or you can start down, but when all is said and done, if you can't see the airport at the MDA, you shoot the missed regardless of how you got to the MDA.

Yeah, my point was that this seemed a little problematic, yet also had some factually correct aspects too. But it's interesting that it was suggesting that "the better technique" was to get to the MDA with minimal delay (obviously you did it with proper, safe descent rates and precise level offs).

I also remember a legal-like discussion of whether you had to see the airport or if you just had to see something identifiable as related to the airport (like a Gas station that you knew was 1 block away). I think this was probably in an "Aftermath" article in Flying Magazine or something.

Ironically, several years ago, there was a good hot, debate on the Airdisaster forums between a young technology guy and an old traditionalist (both professional pilots). The young guy was bashing NDB/ADF approaches (pretty much the same as any other non-precision approach- except for a weaker, wobbly, less precise signal), and the old traditionalist was saying "nothing wrong" and that a pilot who can't handle one is not a competent pilot.

And yeah, plenty of paralells between this and your Dad's story and what you did in a Jetstream with no flight director and what you do now.

Absolutely, approaches vary in how challenging they are. And they vary in many ways...lots of step downs in a fast plane is one challenge, a hand-flown ILS to 200 feet in a heavy, blustery snowstorm is another. Mild IMC vs. severe weather, gentle vs. mountanous terrain- these have a huge influence on how challenging an approach is. And maybe in severe thunderstorms, the PIC needs to temporarly ban any instrument approach.

But with competent pilots who properly breif for the approach and use proper CRM, and don't comprimise the built in safety margins of the minimums, and etc....

Of course, landing a 777 in severe VMC is another operation that, on rare occasions, can apparently be too challenging.

[Gabriel]

Dad just handed the guy the plate for the ILS at Butte, Montana and said "here, look at this one." All he heard from the jumpseat was "HOLY $#!T!"

HOLY $#!T!!!!

With minimums of 1200ft and 4 miles, that's the first ILS I see that can be below minimums even in VMC.

[3WE]

In this thread, 3WE will explain to us how, in spite of the higher workloads and increased opportunities for pilot error, this age-old technique of dive and drive, the cause of many misfortunes, is still a safe SOP.

I will be interested to see if our resident pilots agree and concur or if they think it is time that all commercial operators insist on a stabilized approach.

Take it away 3WE...

Now that this thread has slowed, and most folks have spoken, and in spite of FAR's and TERPS standards and the abilities of professional pilots to succesfully level off at a predetermined altitude and location, Evan will review this thread to see if our resident pilots agreed and concurred that non-precision approaches with step downs should be prohibited for airlineer operations.

Take it away Evan.

[Evan]

Now that this thread has slowed, and most folks have spoken, and in spite of FAR's and TERPS standards and the abilities of professional pilots to succesfully level off at a predetermined altitude and location, Evan will review this thread to see if our resident pilots agreed and concurred that non-precision approaches with step downs should be prohibited for airlineer operations.

Take it away Evan.

Well, let's see... thus far we have heard from two pros and one highly esteemed 'amateur':

syndersnapshots:

Having done MANY D & D approaches in my time, I will say that I like the constant rate approaches MUCH better. It takes a lot of the calculations--and thus an opportunity for screwing up--out of the mix.

While admitting that D&D is less desirable and has more opportunity for screwing up, he also asserts that it is a safe procedure. Interesting.

Gabriel:

I agree that step-down approaches are more high-workload, offer more opportunities for mistakes, and are hence involves more risks than an ILS or ILS-like approach.

Also admits to the elevated risk of D&D, yet deems the procedure safe. Also interesting.

BoeingBobby:

At minimums and end of time, NO PARTS OF THE APPROACH LIGHTS VISIBLE, NO RUNWAY? GO AROUND, END OF STORY!

Has not really said anything about D&D being safe or not, but his ALL CAPS about one of the pitfalls of D&D is somewhat telling.

Here's what I make of this:

D&D elevates risk, workload, and opportunity for error but is perfectly safe if executed by disciplined, alert and very capable pilots with absolute adherence to the MDA/MAP. (Nobody has yet commented on the aspect of elevated pitch at MDA causing VDP disorientation among pilots accustomed to constant rate approaches.)

So, what do we have out there? Not all pilots are up to the task required by D&D. It presents an opportunity for the ones who aren't to shine in tomorrow's headlines. Some pilots who excel in constant rate approaches will be a bit out of their element on D&D. Most commercial pilots gain most of their instincts with constant rate approaches.

I think by now we have come to understand that the main threat to aviation is either the random pilot with poor judgment or the momentary lapse of judgment an otherwise capable pilot might experience and that the key to overcoming this risk lies in establishing certain standards and minimizing opportunities for error (pitfalls) wherever possible. We want those lapses to occur in environments that can best tolerate them. Both constant rate and dive and drive are susceptible to error, but dive and drive is more susceptible because it is less forgiving, more demanding and more complex. I also think it encourages extended runway hunting beyond the MAP in pilots with less than perfect discipline. Logic would tell us to standardize against dive and drive (and we mostly have). So why do we still allow it?

So, to rephrase the question a bit: even if dive and drive is deemed safe in the right hands, considering the small but tragically demonstrated percentage of pilots who are not the right hands (and who will always be there) wouldn't aviation safety be better off overall without it? Because that's really the question we have to ask.

[Gabriel]

So, to rephrase the question a bit: even if dive and drive is deemed safe in the right hands, considering the small but tragically demonstrated percentage of pilots who are not the right hands (and who will always be there) wouldn't aviation safety be better off overall without it? Because that's really the question we have to ask.

For the Nth time, yes, it would be safer.
Are you willing to take all steps that could make aviation safer?
How about forbid IMC all together?
How about forbid visual approach all together?
Let's keep only ILS or ILS-like approaches, but only in daylight VMC and only as long as the runway has PAPI or VASI.

By the way:
More workload? Yes.
More opportunities for mistakes? Yes.
Less margin of error????? Hmmmm, I don't think I agree with that one.

[3WE]

Well, let's see... thus far we have heard from two pros and two highly esteemed 'amateurs':

syndersnapshots:
While admitting that D&D is less desirable and has more opportunity for screwing up, he also asserts that it is a safe procedure. Interesting.

Gabriel:
Also admits to the elevated risk of D&D, yet deems the procedure safe. Also interesting.

BoeingBobby:
Has not really said anything about D&D being safe or not, but his ALL CAPS about one of the pitfalls of D&D is somewhat telling.

3WE:
When properely briefed and conducted by a two person crew and their head is in the game, it's safe and does not neccesarily need to be prohibited.

Fixed

[3WE]

So, to rephrase the question a bit: even if dive and drive is deemed safe in the right hands, considering the small but tragically demonstrated percentage of pilots who are not the right hands (and who will always be there) wouldn't aviation safety be better off overall without it? Because that's really the question we have to ask.

Actually, Evan, what do you think of this question:

Given that computer integrated and calculated navigation is spreading so rapidly (and getting more economical and more capable) and makes it so easy (and hopefully frees you up to do more important things like being extra sure you don't descend into the ground) why in the hell aren't we just using constant descent rates 99.99% of the time to replace step downs?

Now, sadly, that kills what was a great (but usually doable) challenge to traditional pilots to skillfully guide planes down to fairly precise (and safe) places with a good safety buffer- and which probably had a fringe benefit of making them damn good at an ILS to 1000 ft AGL in softer IMC...

(Still betting an expired approach plate that UPS was doing some sort of constant rate thing)