Exactly, Airbubba. See F-GITA accident.
From an earlier post of mine:
.....There was no FCU malfunction, the overrun occured because the crew didn't know that at the end of the VNAV descent, which coincided roghly with the MAP, the autothrottle would have commanded go around thrust (incredibly, during the investigation, they found out all other AF 744 pilots didn't know as well this behaviour).
The copilot, when he felt the thrust levers advancing, instead of disconnecting pulled them back and hold them back (!), yes, all except N°1 (small hand maybe...).
At touchdown of course there was no spoiler nor autobrake, nor the captain was aware of what was going on.
Despite heavy braking, eng 1 was still producing full thrust when they skid to the right into the lagoon...
Firefighters eventually shut the engine down with water...
F-GITA was returned to service, and the NTSB recommended the E&E bay shouldn't be positioned there in the next millennium
RatherBeFlying, my modest opinion as posted some months ago:
"DIVE & DRIVE IS SAFER!
Yes Dive&Drive is safer.
And also much easier.
Those who find the level segment destabilizing simply have lost all their handling skills and try to hide behind the constant angle magical solution (which doesn't work, and puts them in an even worst and dangerous situation).
They try to turn a NON precision approach into a PRECISION one, simply because they don't know how to fly it and are a bit scared of it.
These are the pilots who crash in the non precision approach, the dangerous **** of Guam and many other places!
Ok, let's cool down and try to explain.
Basically, there are two kinds of NPA: the easy ones and the difficult ones.
That means: the ones with various altitude vs distance check points reported on the plate, and those without anything.
These can be flown in good weather or bad weather.
When I say bad weather I mean ceiling just above the MDA. Poor visibility, of course.
Avionics can be advanced or old.
AP ON or raw data manual flying.
In an argument like this we must assume the worst scenario and examine it.
No doubt once we master the most difficult scenario we can master the easy one.
So the scenario is: NDB over the field, and nothing else!
Outbound leg of, say, 3 minutes, turn back inbound and descend to the MDA.
MAP over the beacon.
Those who plan for a constant descent will calculate a certain VS versus a certain speed, trying to correct for the wind.
They think they'll be able to reach VDP (Visual Descent Point, the point at which you can leave MDA on a 3° slope to the runway) using the calculated parameters.
Very funny!
Actually, I'll tell you what will happen:
First of all, when you overfly the NDB outbound your timing will be inaccurate, because of the dead cone and the instrument tolerances, and I've noticed this error can reach one mile (!);
Second, all your meticolous calculations will be falsified by the real wind, which is different from what you had expected at different altitudes throughout the approach; also, because of the difficulty involved in maintaining exactly the speed and VS you had planned.
The result will be: you'll certainly NOT reach MDA at the VDP, and what is worst you won't know if you are high or low on your imaginary profile.
In both cases, a missed approach is very likely, since you will end up too far out, or too close and high.
All these unnecessary goarounds reduce safety (more time spent in the air thus more chances of failures, more stress and pressure with low fuel and so on...).
But now, Pittsle, you are with me in the cockpit:
we'll fly this approach using the Dive&Drive method.
With this technique, it's not even necessary to make any meticolous calculations, as we'll know for sure on which side of the imaginary glide we are, so we'll know exactly what to expect and what to do.
Leaving each altitude step you will initially set about 1500ft/min, then approaching the selected altitude you'll reduce to about 1000ft/min.
I say about: it does't matter if your VS is not exactly a certain value.
This will certainly NOT trigger any GPWS warning.
You'll realize soon how easier it is to concentrate on one thing at a time: descending to your next altitude and levelling off, till the next one, instead of worrying all the time if your VS is still correct, if you haven't screwed it up, and if you'll reach the next step high or low...
Just one figure in your mind: the altitude you are descending to.
We'll have the Landing cklist completed down to flaps 15 on the 737 (flaps 10 if single eng.) before turning on final.
Once established on final you'll descend to the MDA the same way: there again, you'll notice how easy and safe it is to descend worrying only about one thing: levelling off at the MDA.
You have certainly noticed how difficult it is for your friends who use the other philosophy to control the path of the airplane and make a decision at MDA: they have to fly a descending airplane, monitor the altitude not to bust the minima, look outside for the runway which can be offset by a large amount in a non prec. approach, find it, assess their height in relation to the PAPI to decide about the feasibility of the landing, ALL THAT SIMULTANEOUSLY.
Not so in our cockpit: after a nice and smooth leveloff at MDA, the airplane will be stabilised, we'll know for sure on which side of the profile we are, and we'll have plenty of time to set the Missed approach altitude in the MCP, look for the runway, find it, and make our decision.
Another important point to consider in bad weather: if the ceiling is roughly coincident with your MDA, if you descend with a constant rate and plan to decide at MDA, one little limb of the cloud is sufficient to keep you in IMC and force you to goaround! while with a longer level segment at MDA you have many more chances to exit the cloud and become VMC.
Ok, Pittsle, now we are approaching the VDP and have the runway in sight: as soon as the PAPI becomes three red one white, you call flaps 30, set Vat, and leave the minima on the PAPI and land.
If the minima is lower than 500ft, you have two options:
you can plan a flaps15 landing, or you can arbitraryly set MDA=500ft.
This way you ARE configured by 500ft.
Summing up: you know exactly what is happening instead of hoping for a miracle to end up exactly at the VDP at MDA, you know what to do, much easier job thus safer job, and what is a sort of nightmare to more than one pilot becomes very easy and effective.
Once again, if you master this scenario, you can apply the same rules to an easy one (as described at the beginning) or whatever else you like, even the constant descent, of course if you are in CAVOK even my dog can fly a nice touristic approach
One last pearl of wisdom : busting the minima by 30 or 50 ft, although very very ugly, has never killed anybody.
Being flown by the airplane, instead of flying it, like the Guam ****, has.
LEM