LPV approach

[jtsjc1]

First Hardy THANK YOU! You and the team have created the most amazing piece of software I've ever used. I am referencing every book on the 744 that I have and am amazed at the detail. I'm also amazed at how much I never knew about the Queen. To you and your team Salute!  Now to my question, is the 744 equipped to fly LPV approaches?  I understand its an RNAV approach but with lower minima?  I believe the a/c must also have  WAAS capable GPS.  I'm no expert in IFR flying so if I sound stupid I apologize in advance.

[Hardy Heinlin]

Thanks.

I don't know.


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[Jeroen Hoppenbrouwers]

http://en.wikipedia.org/wiki/Localizer_performance_with_vertical_guidance

I don't think the 744 is equipped for this, as the vertical component of the GPS+WAAS isn't integrated in the system at all (as far as I know).


Hoppie

[Hardy Heinlin]

I read some stuff about it, also on Wikipedia.

I just don't know if any 744 is prepared for it.

GPS is integrated in two of the 744's MMRs which provide the deviation values for ILS, MLS, and ... maybe WAAS. That would be a 2-channel approach, theoretically.


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[DougSnow]

Commercial airliners aren't WAAS equipped, except in some unique circumstances.

[jtsjc1]

Thanks for the replies everyone.  I didn't think WAAS was on commercial airliners GPS I mostly see it on G/A aircraft.

[Jeroen Hoppenbrouwers]

It's the typical stuff. Airliners are equipped with the absolute minimum of boxes to legally fly the routes they commercially fly. Everything on top of that is considered expensive (weight!) luxury. GA (and especially the flexible business aircraft) is an entirely different market.


Hoppie

[Vnav]

Hi,

From the current B737 FCTM - p 5.61 (my edition of the B744 FCTM is outdated and makes no reference to LPV):
Boeing airplanes are not equipped to utilize LPV minimums.

Happy landings.

[jtsjc1]

Interesting. I guess flying the approach in LNAV/VNAV is good enough for the airlines. The minimums aren't much different. Or just fly the ILS.

[Jeroen Hoppenbrouwers]

The big thing about LPV is that it opens up a large amount of airfields that do not have ILS. These are typically not the large airports that the commercial airliners visit, but the smaller regional fields where GA is the norm. An ILS CAT I isn't much more than a let-down to safely drop out of the clouds, followed by a manual landing. This can safely be replaced by a well-monitored GPS guidance.

You did not ever let the aircraft autoland on an ILS that wasn't certified and protected in CAT III, right?     :twisted:


Hoppie

[DougSnow]

The only us airline that I'm aware of that has WAAS is Horizon Airlines, from the US Pacific Northwest, due to some of the unique approaches they fly.

[jtsjc1]

The big thing about LPV is that it opens up a large amount of airfields that do not have ILS. These are typically not the large airports that the commercial airliners visit, but the smaller regional fields where GA is the norm. An ILS CAT I isn't much more than a let-down to safely drop out of the clouds, followed by a manual landing. This can safely be replaced by a well-monitored GPS guidance.

You did not ever let the aircraft autoland on an ILS that wasn't certified and protected in CAT III, right?     :twisted:


Hoppie

True Hoppie.  I like the 744 flying the "old school" ILS.

[Balt]

WAAS, as others have said, is not used by any RPT operations to my knowledge.

But there is of course the newer (and better) GLS approach that's been trialled for (I think) a couple of years in Sydney (and some other airports in Europe/US) which is based on the Honeywell GBAS SLS-4000 system which transmits (in real time) correction data for a selected runway/approach. This in principle is just a differential GPS system, and is a fully GNSS based system, i.e. can use not just GPS, but also is capable of integrating GLONASS/Galileo/Beidou satellite information. I don't think GLONASS or Beidou are being used at this stage though (Galileo is not yet fully deployed).

The accuracy of the glide path information is to within a couple of meters, laterally much better than that. Check this link for more information:

http://www.afceaboston.com/documents/events/cnsatm2007/presentations/2007%20CNSATM%20Presentations/04-26-2007%20Thursday/Session%20Rm%203/1-%20GLS_RNP%20AFCEA%20CNS%20ATM%20Conf%204_25_07%20Imrich.pdf


Qantas has been running these trials with parts of their B738 and A388 fleet. I seem to recall they're now using GLS approaches in Sydney on a regular and operational basis.

Cheers

- Balt

[jtsjc1]

Hi Balt they are also using GLS approaches here in NJ (EWR) due to some obstructions to the ILS on some approaches. Thanks for the link btw.  Joe

[IefCooreman]

Wasn't WAAS developed in times when gps data was deliberately made less accurate by the military guys? (forgot the word for that)

[Phil Bunch]

Wasn't WAAS developed in times when gps data was deliberately made less accurate by the military guys? (forgot the word for that)

Wikipedia has a section on the history of WAAS:


https://en.wikipedia.org/wiki/Wide_Area_Augmentation_System

History section is here:

https://en.wikipedia.org/wiki/Wide_Area_Augmentation_System#History_and_development

[Magoo]

Autolands can be done regardless of whether or not the runway is Cat III or not, ILS protected or not.

[Jeroen Hoppenbrouwers]

Magoo, are you sure? How can you allow a plane to hit concrete hands off without calibration and protection? Only in good vis or so?

Serious question, really.


Hoppie

[Magoo]

Because you keep your hands on, just in case😄.  If the runway has been approved as an auto land runway it doesn't matter if the ils is protected or not,so long as you have a valid ils signal and no " no auto land " eicas message, you are good to go.

[IefCooreman]

I confirm, autoland capability only requires a "normal" ILS. For a normal ILS, the pilot can monitor the reliability by looking outside. In low vis, there isn't enough time below minimums for this, so the ILS gets more protection from the ground.

Situations where this might happen: practice low vis approaches to maintain low vis qualification of both aircraft and crew, or pretty much any failure not leading to a loss of the autoland functionality. Simple example: pilot incapacitation :-).