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with UPS and a calculated glidepath a clear approach plate and a decisive controller.
And as stated, there are more safety buffers with a non precision approach...but you choose to dismiss that- it's a good bit less critical to have to level off 700 feet above an obstruction than 200 feet.
Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.
A night like that in dog s**t weather, look for land 3 or land 2 and watch the magic happen!
And what if it doesn't? (becasue something failed, because you did a human mistake with some setting...)
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
Certainly you can crash anything, anywhere at anytime but which is safer?
That's the wrong question, because the answer is daylight VFR CAVU, no winds, no icing, in an airplane that is quite lighter than the max weight for the operation despite having twice the fuel required for the flight, the runways are long, wide, without obstacles and clear of water or other contamination, and the landing runway has an ILS or the airplane is WAAS equiped and the ariport has a WAAS approach, the airplane has envelope protection, and the flight crew is ITS and BoingBobby, and there are no other aircraft 100NM and 5000ft around.
The question is, which is acceptably unsafe?
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
In the developed world, yes , I would advocate that restriction. No aircraft lacking the ability to execute a stable approach shall operate revenue flights, and forbid dive and drive approaches. And just out of curiosity, what aircraft currently serving more than 50 pax, operating in the developed world and lacking this capability are we talking about here?
I think that there are still several pre-NG 737s, DC-9s and oldish MD-80 flying around in the US. I don't know if all of them have been updated to a FMS with vertical navigation and capability to generate a virtual glide slope.
A constant "virtual" GS is much safer than dive'n drive, if the GS is correctly entered.
In my experience, attempting to fly a constant GS / constant VS in an airplane that is not equipped to produce a virtual GS is more dangerous than dive'n drive.
I agree with 3WE that flying a dive'n drive in an airplane with AP and AT is not so difficult. What you do is:
- Configrue for landing early, while still in the horizontal leg to cross the first fix at the first crossing altitude. The AP will be at ALT HOLD at that altitude, and the AT will be the IAS for Vapp.
- Set the minimums at the MDA.
- Select a vertical speed that is higher than the maximum one that you'd need in any segment. -1000fpm normally works in jets.
- When crossing the first fix, select the crossing altitude of the next fix.
- The plane will descent to that altitude at constant speed Vapp and level off adjusting the thrust again to keep Vapp. Monitor.
- Repeat the above as many times as steps there are.
- For the last step, replace the "next crossing altitude" (that doesn't exist) for the MDA.
- If before the MDA you get the runway in sight, disconnect the AP and hand fly the remaining of the approach (you can leave the AT on)
- If you listen "Minimums" or equivalent warning, or the PNF calls "Minimums", or if the plane levels off at the MDA, go around.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
A night like that in dog s**t weather, look for land 3 or land 2 and watch the magic happen!
Touche'
Then off to the hotel for a good day's sleep with doors slamming and maids tapping on every door in the hall saying "housekeeping!"--when they're not chatting at the top of their lungs with their friend who is working halfway down the hall. Then up for another fun-filled night!
The "keep my tail out of trouble" disclaimer: Though I work in the airline industry, anything I post on here is my own speculation or opinion. Nothing I post is to be construed as "official" information from any air carrier or any other entity.
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.
Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.
Then off to the hotel for a good day's sleep with doors slamming and maids tapping on every door in the hall saying "housekeeping!"--when they're not chatting at the top of their lungs with their friend who is working halfway down the hall. Then up for another fun-filled night!
You must have been at the same place I was the other day! 5 Towns ?
And what if it doesn't? (becasue something failed, because you did a human mistake with some setting...)
If I am PIC in the aircraft? (For that matter if I was sitting in the jump seat) Pilot flying, inside monitoring the approach. Pilot not flying looking out. At the minimums call, "approach lights, runway in sight or no runway" GO AROUND! END OF STORY!!
At minimums and end of time, NO PARTS OF THE APPROACH LIGHTS VISIBLE, NO RUNWAY? GO AROUND, END OF STORY!
Evan seems to like black and white and it doesn't get much blacker or whiter than that.
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. PDX only uses this approach when the weather is crappy and the wind is howling from the south. The step-downs are there because of the rising terrain to the north, so it can be a fun ride with the turbulence. The VDP is right about at the north side of the Columbia River which has a pretty good hill. 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!
The "keep my tail out of trouble" disclaimer: Though I work in the airline industry, anything I post on here is my own speculation or opinion. Nothing I post is to be construed as "official" information from any air carrier or any other entity.
How does this work with dive and drive? Isn't the drive part about searching for the runway at minimums?
Nope. Re-read my procedure.
While it's legal to fly level at minimums until you see the runway or reach the MAP, it's not considered a good practice. If you level off at minimums and without seing the runway yet, chances are that you won't see it or, if you eventually do, you'll be too high (relaitvely) and would need a too steep descent to make it.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
Nope. Re-read my procedure.
While it's legal to fly level at minimums until you see the runway or reach the MAP, it's not considered a good practice. If you level off at minimums and without seing the runway yet, chances are that you won't see it or, if you eventually do, you'll be too high (relaitvely) and would need a too steep descent to make it.
I remember various mental gyrations to devise a VDP in approaches where one wasn't defined, beyond which a realistic landing wasn't possible. 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.
Do they make non-precision approaches safer? I think so. Does that mean D & D approaches are inherently unsafe? Of course not. Like anything else--be it cruising over the Atlantic, or shooting a visual approach, or landing on a short runway--pilot proficiency, pilot knowledge, and the way the pilot approaches the situation are the real keys to safety.
The "keep my tail out of trouble" disclaimer: Though I work in the airline industry, anything I post on here is my own speculation or opinion. Nothing I post is to be construed as "official" information from any air carrier or any other entity.
Nope. Re-read my procedure.
While it's legal to fly level at minimums until you see the runway or reach the MAP, it's not considered a good practice. If you level off at minimums and without seing the runway yet, chances are that you won't see it or, if you eventually do, you'll be too high (relaitvely) and would need a too steep descent to make it.
And yet how many target-focused, task oriented and just plain tired pilots will hunt a little bit further along for that glimmer of runway...
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.
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