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MDA for CONSTANT DESCENT NPA

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MDA for CONSTANT DESCENT NPA

Old 8th Jan 2010, 21:02
  #61 (permalink)  
 
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BOAC...from my discussion with the senior technical people at Boeing, the intent was to bring VNAV down TO a DH because of the accuracy of the system. The philosophy was referred to as "flying to near ILS limits using VNAV and GPS/LNAV/LOC overlays."

In absence of an integrated/automated VNAV system (AFDS) but using FPA or VS, it would be more correct to use the Derived Decision Height.

Would I bust a candidate for not using a DDH on a VNAV approach? It depends on the training philosophy of the company. What were the standards of training? There are many factors to consider. It would be a good debrief item for sure.
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Old 8th Jan 2010, 21:10
  #62 (permalink)  
 
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The Rockwell-Collins system has a VGP function. Arm APP and VNAV, VGP will be armed and captured just like a glide slope. When VGP is captured, the ALT Selector will act just as on an ILS and be set to missed approach altitude. VGP presentation shows a GP down to 50 TCH.

GF
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Old 8th Jan 2010, 21:12
  #63 (permalink)  
 
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Galaxy...I want to fly your airplane!
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Old 8th Jan 2010, 21:21
  #64 (permalink)  
 
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GF, you've described the Honeywell Primus Epic system too! The system is designed to be operated exactly the same for an ILS or non localiser based non-presision approach. The APP button responds to the selected nav source and FMS programmed approach. By either arming LOC/GS or LNAV/VGP
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Old 8th Jan 2010, 21:29
  #65 (permalink)  
 
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VNAV/LNAV approaches on boeings were obviously designed to be flown using automatics although flight director usage is sufficient. The IAN thingy has the same presentation to the pilot flying any non precision approaches as any precision approach (GLS or ILS for us) and therefore can be easily used flying "raw data", following the flight director or fully autocoupled. If you forget to disconnect the pilot because you think its just an ILS and you do an autoland you will get a warning at 100' with a yellow AUTOPILOT on the PFD and auto-callout "AUTOPILOT". If you set up the system correctly (select the approach from the database, fill in the descend forecast page and press APP when cleared for it) it is a very nice and stable way to fly non precision approaches, besides it nearly removes the difference in SOPs and presentation between precision and non precision approaches.

Of course that could be seen as catering to reduced training and only the low hour pilots, however i do think it is a perfect way to make flying safer and reducing the risk of mishaps and CFITs.

IAN is standard for 737s since 2006, dunno if it is available yet on other boeing types allthough we do know it will be available on the 787 (and boeing promises that you can do operate 737 and 787 in MFF, but thats another thing).
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Old 8th Jan 2010, 22:25
  #66 (permalink)  
 
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Denti, what is MMF?
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Old 8th Jan 2010, 22:34
  #67 (permalink)  
 
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Further to GF and FE Hoppy's posts, the CitationJet 'plus' series has the same feature of VGP during an LNAV/VNAV approach with the altitude pre-select working in the same way as an ILS.

The whole aircraft probably costs the same as the stabiliser screw jack on the other type that I fly (744) but it has better displays and VNAV capabilities. I guess that's 20 years of progress for you.

I always teach guys to try and fly every instrument approach as much like an ILS as possible, so I'm firmly in the CDA camp (+50ft).
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Old 9th Jan 2010, 00:17
  #68 (permalink)  
 
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777AV8R

Check your PMs, please

GF
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Old 9th Jan 2010, 04:03
  #69 (permalink)  
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Superb 777av8r!

As the starter of this particular thread, I have read the various posts with interest.The posts from 411a, although highly predictable, and similar to my great-grandfathers, (he flew in the 40s and 50s), and are always good for a laugh.Thank you kindly 777av8r, your post is excellent, ive copied it and handed over to my FTM, if you dont mind by way of explanation of said add-on procedure.Pete.
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Old 9th Jan 2010, 05:07
  #70 (permalink)  
 
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@Spooky: MFF means Mixed Fleet Flying. Which means the ability to qualify your crews on two different types and fly them in a mixed operation. Most commonly that is currently done on Airbus types, for example A320 family with A330s, but we had the approval for MFF between 737/757 and 737/767 although we never actually did that.

Interesting to read though that Boeing doesn't offer IAN on the 747 yet, but would expect it on the -800.
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Old 9th Jan 2010, 05:50
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Something that hasn't been brought up is the engine response time. In a L1011 (I haven't flown one, but have a 747-200) the time to get the engines from a high power, high drag (and noise) situation is relatively low, with a GE 777 ( and other high bypass engines) it would be very significant and you would end up with a very destabilised approach unless you are both very good at it. With the 777 you can have FPA and track select and get a very accurate NPA, limited only by the accuracy of the charts.
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Old 9th Jan 2010, 08:03
  #72 (permalink)  
 
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In a L1011 (I haven't flown one, but have a 747-200) ...
Now there's an interesting response....
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Old 9th Jan 2010, 11:43
  #73 (permalink)  
 
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Denti, the 747-8 will have the IAN feature and I would expect to see it available in the 777 fairly soon as well. Thanks for the MFF explanation.
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Old 9th Jan 2010, 17:47
  #74 (permalink)  
 
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GALAXY...

Check PM and personal mail.

Rgds
777
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Old 10th Jan 2010, 08:29
  #75 (permalink)  

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Having a look at the Flight Safety Foundation for recommendations made by their Approach & Landing Accident Reduction campaign might be worthwhile for a few people on here.

Just because someone has done dive & drive and circle to land successfully, doesn't make those methods less of a CFIT risk than a CANPA.

And it's nothing to do with the perceived reduction in 'skill and ability' of 'younger generations'.

Even expert pilots crash aeroplanes.

Approach and Landing Accident Reduction (ALAR) | Flight Safety Foundation

or

SKYbrary - Flight Safety Foundation ALAR Toolkit
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Old 10th Jan 2010, 09:28
  #76 (permalink)  
 
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and therefore can be easily used flying "raw data", following the flight director or fully autocoupled.
The 737 FCTM recommends the autothrottle be switched off whenever manual flying is attempted unless it is climbing after takeoff. One assumes therefore during a CDA approach hand flown on the flight director as above, the pilot would also be using manual throttles. This usually causes some consternation in automated aircraft, as pilots are so ingrained in using full automatics which of course include autothrottle, that their manual throttle handling becomes a trifle hairy to say the least! In turn their speed control is rusty and inevitably approaches can become unstable. It depends largely on the currency of the pilot on manual flying. If not current or slightly nervous, stick to full automatics
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Old 10th Jan 2010, 11:16
  #77 (permalink)  
 
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Umm, the same is true for every single approach. But especially the 737 is a shorthaul aircraft on which a crew usually does 4 to 6 landings a day so that every flight crew member gets 2 or 3 landings. The use of autothrottle or not during approaches is something we discussed elsewhere indepth and this thread is mainly about non precision approaches.

The sentence you quote up there just states that it is nice to be able to fly a defacto raw data (non flight director of course) non precision approach much easier in IAN (which you should know and use as a current 737 pilot) than in LNAV/VNAV or heaven forbid LNAV/VS. Nothing in there is about autothrottle usage at all, any current pilot should be aware of how to fly according to his company SOPs and the use of autothrottle or not during manual flight, ours actually use the autothrottle ARM feature for the last 20 odd years without any problem so far.

As for manual flight recency, a lot of that depends on your company atttitude towards it, but i think the following from our SOPs gives me quite a bit of that if i want to:

Continuous use of automatic systems leads to loss of basic knowledge of power settings/pitch attitudes and reduces the ability to fly accurately with a low workload. Pilots should therefore regularly fly the aircraft manually, with emphasis on manual departures/ approaches with and without the flight director.
The problem with allways sticking to automatics if uncomfortable is something that can lead to serious problems with raw data flying when necessary and currently a bad trend in the industry, i would rather avoid an airline that doesn't train its pilots enough to be able to fly raw data at all times.
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Old 10th Jan 2010, 13:30
  #78 (permalink)  
 
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50 ft

The regulatory approvals for DA and MDA differ, in most of the countries the height lost in case of a goaround is not factored for a MDA. So if you have a chart that states DA for a LNAV/VNAV approach do not add 50 ft, otherwise you would have to add.


Happy Landings

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Old 10th Jan 2010, 20:08
  #79 (permalink)  
 
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Few years back I was very involved with the CDA topic.

At that time the 50 feet increment was just an arbitrary number that some operators used but in fact the requirement was just to establish an SOP with an increase to MDA to make sure this was not busted during the G/A.
Of course this depends on the altitude loss for each particular aircraft type.
The 50 feet number may be a good one size fits "all" but maybe not required as standard by most regulators.

No increase to minimums was only allowed *if* a DA was published *and* the operator had received authorization for such operations.

Something to keep in mind if you are using Baro VNAV is that most of the FMS's can not be compensated for temperature.
(An ILS GS is not affected by this.)

Operators have been using CDA for more than 25 years with excellent results.(Adding cushion to MDA) Published DA's for NPA's and authorizations for their use is not very old

As an active line pilot/Check Airman with some 32K hours and still a few years to go I celebrate the excellent posts provided here promoting the use of CDA.

Brgds.

Manuel

Last edited by manuel ortiz; 11th Jan 2010 at 01:34.
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