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MarkW

Aerosoft CRJ 500/700 Update 1.0.5.0 LNAV

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I know the other thread was locked, just wanted to continue hopefully on a more constructive basis.

I flew the CRJ with 1.0.5.0 update last night.  For me I noticed the LNAV was very solid, made correct turns with no hunting or S-turns that I noticed.  All was good until I reached the initial fix for the RNAV approach to runway 16 at YMML.  The aircraft just flew right past it in the current heading and I had to use HDG mode to continue with the approach and landing.  Is there something I need to do to engage the RNAV approach?


Mark W   CYYZ      

My Simhttps://goo.gl/photos/oic45LSoaHKEgU8E9

My Concorde Tutorial Videos available here:  https://www.youtube.com/user/UPS1000
 

 

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"RNAV capability" means at the most basic level the capability to navigate on a given RNAV route segment, whether in the enroute structure or terminal area. The CRJ is thus most definitely RNAV capable, although most CRJs lack the coupled VNAV mode that @Andreas Stangenesis referring to.

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40 minutes ago, Andreas Stangenes said:

AFAIK the CRJ isnt rnav capable. You can fly rnav approach, but you do that in lnav mode with the vs speed selected. 

It can do standard RNAV approaches to LNAV minimums using VS for the descent. “Plain” RNAV does not require VNAV, and it still “counts” as an RNAV approach. Coupled VNAV is an option in the real CRJ, and that option is selectable via the EFB setup menu in the Aerosoft version. It adds a VNAV button to the autopilot control panel.

With that option, the CRJ can do an regular RNAV approach to LNAV/VNAV minimums, which are usually lower than LNAV only. In both cases, the pilots need to closely monitor their descent to insure that the altitude at intermediate waypoints along the approach patch remain above any crossing restrictions shown on the approach plate. These approaches are flown in NAV mode.

There is an available STC developed by Rockwell Collins a few years ago that can give a CRJ the ability to perform a WAAS/LPV RNAV approach which uses a GPS-calculated glide path and is flown similar to an ILS in APP mode. This option is very uncommon in the airline CRJ fleets, as it quite expensive to add. I do not think there are any plans to add this feature to the Aerosoft version.

What a real CRJ cannot do is an RNP RNAV approach that uses curved RF legs. The main reason is that the autopilot does not have sufficient precision to fly the lateral path to within RNP limits. The real CRJ autopilot uses a fixed bank angle when turning, while RF legs require an autopilot that can use a variable bank angle. 

RNP/AR RNAV approaches do not appear in the nav database of a real CRJ. They do appear in the sim version because the Aerosoft and Navigraph add-on databases include every available approach at every airport. The sim version s unlikely to fly these procedures correctly, and trying to load them can cause graphics and performance problems.

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Jim Barrett

Licensed Airframe & Powerplant Mechanic, Avionics, Electrical & Air Data Systems Specialist. Qualified on: Falcon 900, CRJ-200, Dornier 328-100, Hawker 850XP and 1000, Lear 35, 45, 55 and 60, Gulfstream IV and 550, Embraer 135, Beech Premiere and 400A, MD-80.

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Ya they can fly RNAV appraoches IRL to LNAV mins so it technically should be able to so it. 

 

Its funny that the freeware CJ4 mod can do this (perfectly) but a $60 payware product from a development team with a ton of experience cannot.


Ron Hamilton

 

"95% is half the truth, but most of it is lies, but if you read half of what is written, you'll be okay." __ Honey Boo Boo's Mom

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Just now, fakeflyer737 said:

Ya they can fly RNAV appraoches IRL to LNAV mins so it technically should be able to so it. 

 

Its funny that the freeware CJ4 mod can do this (perfectly) but a $60 payware product from a development team with a ton of experience cannot.

The Aerosoft CRJ can do standard RNAV (non-RNP) approaches just fine. I have flown dozens of them during testing. You fly the lateral path in FMS-coupled NAV mode and the vertical descent in VS mode.


Jim Barrett

Licensed Airframe & Powerplant Mechanic, Avionics, Electrical & Air Data Systems Specialist. Qualified on: Falcon 900, CRJ-200, Dornier 328-100, Hawker 850XP and 1000, Lear 35, 45, 55 and 60, Gulfstream IV and 550, Embraer 135, Beech Premiere and 400A, MD-80.

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1 hour ago, MarkW said:

I know the other thread was locked, just wanted to continue hopefully on a more constructive basis.

I flew the CRJ with 1.0.5.0 update last night.  For me I noticed the LNAV was very solid, made correct turns with no hunting or S-turns that I noticed.  All was good until I reached the initial fix for the RNAV approach to runway 16 at YMML.  The aircraft just flew right past it in the current heading and I had to use HDG mode to continue with the approach and landing.  Is there something I need to do to engage the RNAV approach?

There are 3 RNAV approaches for runway 16 at YMML. The only one that the (real) CRJ can fly is the RNAV-Z which is a standard GPS-based RNAV. The initial approach fix for the RNAV-Z is BELTA.

The RNAV-M approach (initial fix LUVKA) and the RNAV-P (initial fix EMSEK) are both RNP approaches. These two approaches will not appear in the FMS or a real CRJ. They do appear in the FMS of the sim version, but the autopilot will not fly the lateral path correctly. The real CRJ would not be able to fly these two approaches correctly either if, (due to an error in the database) the RNP approaches were selectable in the FMS ARR page.

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Jim Barrett

Licensed Airframe & Powerplant Mechanic, Avionics, Electrical & Air Data Systems Specialist. Qualified on: Falcon 900, CRJ-200, Dornier 328-100, Hawker 850XP and 1000, Lear 35, 45, 55 and 60, Gulfstream IV and 550, Embraer 135, Beech Premiere and 400A, MD-80.

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23 minutes ago, fakeflyer737 said:

Its funny that the freeware CJ4 mod can do this (perfectly) but a $60 payware product from a development team with a ton of experience cannot.

I guess this has nothing to do with the addon price but rather with the goal to replicate a RW CRJ as precisely as possible. BTW, the P3D version of this CRJ has the same limitation.

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Felix

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2 hours ago, JRBarrett said:

There are 3 RNAV approaches for runway 16 at YMML. The only one that the (real) CRJ can fly is the RNAV-Z which is a standard GPS-based RNAV. The initial approach fix for the RNAV-Z is BELTA.

The RNAV-M approach (initial fix LUVKA) and the RNAV-P (initial fix EMSEK) are both RNP approaches. These two approaches will not appear in the FMS or a real CRJ. They do appear in the FMS of the sim version, but the autopilot will not fly the lateral path correctly. The real CRJ would not be able to fly these two approaches correctly either if, (due to an error in the database) the RNP approaches were selectable in the FMS ARR page.

Thanks Jim.  I was flying the RNAV-Z approach and it did show up correctly in the FMS and the line on the map was connected all the way.  No explanation why it missed the turn....which by the way is very sharp at 90 degrees from the STAR.


Mark W   CYYZ      

My Simhttps://goo.gl/photos/oic45LSoaHKEgU8E9

My Concorde Tutorial Videos available here:  https://www.youtube.com/user/UPS1000
 

 

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On 6/9/2021 at 1:53 PM, JRBarrett said:

With that option, the CRJ can do an regular RNAV approach to LNAV/VNAV minimums, which are usually lower than LNAV only. In both cases, the pilots need to closely monitor their descent to insure that the altitude at intermediate waypoints along the approach patch remain above any crossing restrictions shown on the approach plate. These approaches are flown in NAV mode.

Depending on the FMS software version, you can also use LNAV/VNAV minimums without having coupled VNAV, as long as atmospheric conditions are ISA or above (mainly temperature related for altitude compensation). At least, over here in EASA land this is the case.

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1 hour ago, Prpn said:

Depending on the FMS software version, you can also use LNAV/VNAV minimums without having coupled VNAV, as long as atmospheric conditions are ISA or above (mainly temperature related for altitude compensation). At least, over here in EASA land this is the case.

I believe it is also the case here. Also, last year we were required to remove the FMS temperature compensation menu option in compliance with an FAA Airworthiness Directive. It was found that both Proline 4 and Proline 21 FMS systems had a bug where a missed approach procedure could potentially be displayed (and flown by the autopilot) with a turn opposite to the correct published direction if barometric temperature compensation was enabled in the FMS. That option is no longer available.


Jim Barrett

Licensed Airframe & Powerplant Mechanic, Avionics, Electrical & Air Data Systems Specialist. Qualified on: Falcon 900, CRJ-200, Dornier 328-100, Hawker 850XP and 1000, Lear 35, 45, 55 and 60, Gulfstream IV and 550, Embraer 135, Beech Premiere and 400A, MD-80.

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