VNAV during descent

[evaamo]

Hello all! New owner of the IXEG. Loving this bird so far! Nice job.

I have a problem tho':

 I've had to intervene  with lvl change during my descent two or three times in my last flight (which is the first full automated flight... I've been doing circuits to get a 'feel' of the aircraft). 

The vertical deviation was inside the correct range during the first few minutes after capturing ToD, then it started to shallow the descent until it was no longer descending and basically the auto-throttles had to wake up to maintain the speed. At that time I just pressed level change and everything continued as normal. This kept happening multiple times on different stages of the descent. Winds aloft were mostly calm. The route was SVMI-TNCA.

This is mostly a default XP11 11.41 install with ActiveSky and AviTab. FlywithLua is enabled with just xvisibility script. No other addons or plugins.

I am familiar with the 737 (Zibo in XP or NGX in FSX/NGXu in P3D) so I don't think I did anything to screw up the vertical profile.

Please let me know if you need additional information.  

Thank you!

-E

Enrique Vaamonde

[Litjan]

Hi Enrique,

VNAV descents are really quirky, still. We are working on that - it is not your fault!

You did the correct thing - intervene with FL CHG or V/S when things don´t go well.

Cheers, Jan

 

[evaamo]

Hi Jan! Thanks for the prompt reply. Roger that on the VNAV quirkinesses ;-)

I'm not a professional aviator in real life, however one of the the things that I've learned over the years from my buddies who do fly heavies - 744F, 767F, A300F, A330F, 77F  (do you see a pattern here? hehe)  - is that no aircraft is free of bugs and that there have been moments in which they've had to resort to the "basic" modes in order to comply with ATC or keep the aircraft from doing something stupid that might result in a tea & no biscuits visit to the higher ups in their companies

Thanks again! Looking forward to keep flying the IXEG... it's been fun so far.

-E

 

[Litjan]

Hi Enrique,

please don´t take this as an excuse that our VNAV is not working very well - it should be and we have full intent on fixing it. But I flew the 737 for 10 years, another 6 years of 747-400 and too many years A320... it is a very rare circumstance that I have descended (or seen my FO/CPT use it) using VNAV. Most of the time your routing is not predetermined (vectors, shortcuts) or you are subject to ATC limitations (early/late descent, advised rates of descent). So for me (and many of my fellow pilots) VNAV is a gadget that serves very little practical purpose.

I think VNAV is so important to many flight-simulator pilots because they lack the ability to make accurate descent calculations in their head and they also think that it is "cool" to watch the plane glide down all by itself (and then autoland!). I think that is about as cool as using a Tesla´s autopilot when playing a car racing game .

Oh and yes - we do eventually plan on making a cargo variant for the 737 (I see the pattern!)

Cheers, Jan

 

[evaamo]

Hi Jan!

Thanks for your reply! Your stories about VNAV are 100% similar to what I've heard from my friends. Of all the aircraft you flew (or fly?) I wonder if the A320 was the one who had the most "bugs" that required workaround by the crew?. I've heard some interesting stories about it. On the other hand, as an Aerowinx PSX user, I'm jealous you got to fly in the Queen!.

>>I think that is about as cool as using a Tesla´s autopilot when playing a car racing game .

Haha!!! That's a fantastic analogy!!! I'm more fond of virtual flying more classic stuff (such as the IXEG, the 727, MD-80, A300, Etc.) because it definitely poses more challenges... don't find much joy on more automated stuff such as an A320 or a 787. But then again... to each their own.

Anyway, thanks so much for you replies again and I'll be definitely be looking forward to the cargo variant!!! Like a good friend of mine uses to say (and believe me, it sounds more hilarious in spanish): "cargo don't squeal!" (la carga no chilla!).

Cheers!

-E

 

 

[rcahill]

Myself, I will rarely use VNAV during descent.  Most of the time, I will initiate my descent using VS and reference the green arc on the ND.  I try to avoid the initial abrupt descent profiles to make the ride easier on the passengers, also trying to avoid big swings in VS as these can be uncomfortable.  I'll sometimes start the initial descent a little bit ahead of schedule (10-15 NM) out and ease it down around 1000fpm until picking up the profile.

I do use VNAV in climb, normally until I'm in a clean configuration and I'll hand-fly to around 10,000, then autopilot.

Robert

[Litjan]

1 hour ago, evaamo said:

la carga no chilla

We say "Cargo kotzt nicht, Cargo motzt nicht" (Cargo doesn´t puke, Cargo doesn´t complain) Or "Paletten statt Purseretten" (Pallets instead of Purserettes).

We sometimes used to fly cargo at night with our 737 Quick-Change versions...and we also had one D-ABWS that was actually a cargo aircraft.

We take pride in our ability to fly idle-power smooth descents (well, the Boeing pilots do) - the ideal way is when you don´t have to add power (or use the speedbrake) until 1000´ AAL. It takes a lot of experience, planning and some luck to work out - everyone has their own secret formulas and special way of doing the math. It usually involves aircraft and airport altitude, weight, speed, wind profile, expected remaining distance, ATC constraints, other traffic - and also strength of nerve, tide of the seas, phase of the moon, and the current position of the Dow Jones index .

Cheers, Jan

 

[evaamo]

21 hours ago, Litjan said:

We say "Cargo kotzt nicht, Cargo motzt nicht" (Cargo doesn´t puke, Cargo doesn´t complain) Or "Paletten statt Purseretten" (Pallets instead of Purserettes).

Haha!!! Ich verstehe genau!!!

That's just hilarious!

Have a great weekend, Jan. Thanks for the laugh.

-E 

[mcflyslim]

Hello friends!
I was already thinking that I was doing something wrong because VNAV really, if there is no interference from the pilot, it is not going well. Jan I am a big fan of CARGO and a variant of IXEG will be very welcome. I like the most classic aircraft like the 727, 737-200 and 737-300, 400 and 500. The NG family is cool, but it doesn't have the charm of a serious classic. The 737-200 is one of my favorites and here in my country, Brazil, it had an affectionate nickname of BREGUINHA something like "Tasteless" in English, that is, something out of fashion. This happened because when the 737-300 arrived, the pilots called it CHIQUE, something like FANCY in English (inside the fashion).

Sorry for my bad English, but I used the google translator to help.

[Litjan]

Hello mcflyslim,

Your english is very good, I understand perfectly! I think making a 737-200 will not be in our future, it is just too different from the "Classics", and there is already a very good model out there by FlyJsim (I envy those guys because they did not have to make the FMS ).

I like "Chique" for the Classics, and I can very well see ourselves make a -400/-500 DLC at some point in time. But let´s bring this one up to completion, first.

Cheers, Jan

 

[ArthurSG006]

15 hours ago, Litjan said:

Hello mcflyslim,

Your english is very good, I understand perfectly! I think making a 737-200 will not be in our future, it is just too different from the "Classics", and there is already a very good model out there by FlyJsim (I envy those guys because they did not have to make the FMS ).

I like "Chique" for the Classics, and I can very well see ourselves make a -400/-500 DLC at some point in time. But let´s bring this one up to completion, first.

Cheers, Jan

 

Maybe a cargo DLC for -300 would be awesome as well

Edited June 6, 2020 by ArthurSG006

[SWA4420]

Yes, VNAV descent is definitely still wonky....have had to use VS to get to/stay on glide.  I do hope this will be fixed when the FMC is updated.  Great plane overall though!  Thanks for your hard work on it, Dev Team!
Jim

[tkyler]