After a fairly uneventful flight from Oakland to Atlanta in P3D, we reached the T/D @ FL423. I had already reset the altitude, autobrake set to 2, checked the landing data flaps 30/142 and gone thru the before descent checklists....... And in disbelief I watch as she reached T/D and kept going in level flight. No engines back to idle, no descending, nothing. Having untold hours in PMDG aircraft, this was mind boggling and I don't understand why she missed it. I heard of someone else in another VA in smartCARS chat had the same issue. Is there a bug that somehow made it through in testing or did I miss something?

 

 

Is there a bug that somehow made it through in testing or did I miss something?

 

Sounds like you missed something. Why were you at FL423? You should be at whatever value is in your CRZ ALT, which should be even thousands (and nobody cruises at 420 - RVSM ends at 410, so the next avail are 430 West and 450 East).

Joseph,

 

The airplane will only descend upon reaching T/D if you have told it that you want it to do so.

 

You do this by being in VNAV as a pitch mode, and having the altitude selector set for a lower altitude.

 

Either way- there is never a reason to "sit in disbelief."  Be the pilot, man!  Take control of the situation and either use the autopilot or the controls themselves and fly that airplane!

 

 

Either way- there is never a reason to "sit in disbelief."  Be the pilot, man!  Take control of the situation and either use the autopilot or the controls themselves and fly that airplane!

 

Lol, epic!

 

 

 

T/D @ FL423

 

Agree with Kyle here - it is a very weird flight level that one.   Also, are you sure you were in VNAV mode as opposed to HOLD mode for the altitude?

 

Regards

what you may have experienced is the fact that at a slower speed the T/D moves towards your dest airport. On the ND there should be a magenta indication wether you're on your VNAV path or above/below. Yesterday I did a flight with the F-Version into Vienna and the 747 also passed the T/D and didn't decent immediately. But the VNAV path was hit so I knew that it would follow this path. Of course the green T/D on the ND didn't show up anymore as it was overflown. But she started her decent, later, but did it. And it was just fine, I came down to 5000 ft (from FL310) where I was supposed to. 

 

ATM I'm getting close to my T/D with the KLM 747 into SXM and she i just starting to deaccelerate down to 250kts indicated.

 

oh and to complete Robert's advice to be the pilot: A friend of mine is Cpt on the 737. She sais: "I would never ever trust my autopilot. It's just an assistance but it's not my boss. And it would fail at just that moment when you're giving up your responsibility".

 

(...)

 

Either way- there is never a reason to "sit in disbelief."  Be the pilot, man!  Take control of the situation and either use the autopilot or the controls themselves and fly that airplane!

 

 

Reminds me of an old controversial AVSIM topic: "Basic airmanship is sorely needed in the flightsim community".  

 

BTW, aren't all PMDG customers "Pay-to-Fly" pilots?  

Sounds like you missed something. Why were you at FL423? You should be at whatever value is in your CRZ ALT, which should be even thousands (and nobody cruises at 420 - RVSM ends at 410, so the next avail are 430 West and 450 East).

I was at FL423 b/c PFPX flight plan had me at FL423 for my altitude, which is what I had entered. And yes I know odd goes west and even goes east. Also to others, yes the LNAV and VNAV buttons were lit. No the HOLD button was not selected. The new altitude was 2700 and it was correct on the selector. T/D came and went, and the magenta indication was on the bottom with 7000+ below and still going. 747 never idled back and started to descend. I still don't know what I missed. Ephedrin yes everything was set like you said, I eventually took A/P off and hand flew her down, having to do some circuits until I was down 4000. 

And yes I know odd goes west and even goes east.

 

Really?  I always thought it was established as default worldwide semi-circular rule, the East/West orientation of the flight level parity:

 

If your aircraft has track between 0° and 179°, your flight level or altitude must be odd (easterly).

If your aircraft has track between 180° and 359°, your flight level or altitude must be even (westerly).

 

I seem to recall a slight however with a North/South track that may slightly alter in certain instances.

 

Perhaps they changed it and caught me unaware?

Just because LNAV and VNAV buttons are lit does it mean the plane will follow the profile.. READ THE FMA!! Make sure you're in VNAV PTH and not VNAV ALT.

 

 

I was at FL423 b/c PFPX flight plan had me at FL423 for my altitude

 

Just because PFPX said you should doesn't mean you should. There's no way a controller would give you that altitude.

 

Where were your hardware throttles during all of this?

 

 

 

And yes I know odd goes west and even goes east.

 

That's not the point though. FL420 is not a valid altitude for flight. FL410 East. FL430 West. FL450 East. Anything in between is IAFDOF.

 

 

 

Perhaps they changed it and caught me unaware?

 

Kinda. You probably just never noticed it. RVSM came into effect as early as 1997. Before that, it was all odd altitudes above FL290 (E): 310 (W), 330 (E), 350 (W), 370 (E), 390 (W), etc. RVSM extended the 1000 foot separation from below FL290 all the way up to FL410, so it became FL290 (E), 300 (W), 310 (E), etc. Above FL410, it's still the old style.

PFPX gives sometimes very weird altitudes to follow and that doesn't mean you have to follow it (sometimes they are wrong). And make sure you use the appropriate 747 profile. The max ceiling for the 747 is FL410. If the PFPX gave you FL423, something is wrong.

 

Same applies to the payload. Pfpx uses specific passenger weight that only with luck will be the same as used in PMDG or another aircraft developer. The correct thing to do about this is: enter your ZFW in the ZFW field in PFPX and the fields needed and you're good to go

I think the question is already nicely answered by my Marc. But just for future plannings a bit of information:

 

First of all, PFPX gives you sometimes really weird things. May it be FL423 as optimum which is not a valid level, or Meters instead of Flightlevels in some places in Asia. There are several different systems in use (Russia uses meters below Transition Altitude, Flightlevel above / China uses Meters, but you fly in Flightlevels like FL391). You always need to double check these things. These are the parts that make flying interesting and the planning somehow really tricky.

 

The next thing is the east/west flight level allocation system (FLAS). It is correct in let's say 90% of the world. Some countries like France and Switzerland however use a north/south FLAS. There you fly even northbound, and odd southbound.

 

Kyle mentioned correctly, that FL420 is not a valid Flightlevel. This however only applies to the planning of it. We use FL420 almost daily. The most common customer at that Flightlevel is Emirates with their A388 inbound EGLL. They are just not able for FL430, but instead of planning them at FL400 they get FL420 very often. It needs to be coordinated, but it is a normal level for us. Just bare in mind that FL420 is outside RVSM airspace, so you need to keep 2000ft separation (FL400/FL440).

 

@ Jason As far as i am aware - and what i had to learn as ATC, a 744 is able to fly at FL450 (max ceiling FL451 i think). I've seen several 744 coming in my sector at FL430 and FL450. But these have always been cargo variants (probably almost empty), so it might be that the Pax version is limited to FL430 or FL410 due to the pressuration system. That's something a pilot has to answer

 

 

 

Be the pilot, man! Take control of the situation and either use the autopilot or the controls themselves and fly that airplane!

 

I fully agree with that. My years in ATC so far have told me that there is a new generation of Pilots that simply loose the ability to be in command. They trust the AP way too much and only believe in their best friend, the magenta dot/line. It is nice to have features today that help a lot with calculation a TOD etc, but it is just simple math to double check it. Takes around 5 seconds and can be done in cruise where you might be bored anyhow. The TOD is anyhow just an indication for you, where you really should start your descend. In the real business, ATC will - except at night - anyway descent you earlier due to agreements with adjacent sectors that need to be met and are based on the daily flow, not on a single aircraft inbound to an airport.

 

And btw...thanks for the great aircraft. It is simply amazing to fly and makes me smile everytime. Keep it up. Everybody really appreciates the work you did and will do.

 

Cheers,

 

 

Volker Goemmel

 

 

Kyle mentioned correctly, that FL420 is not a valid Flightlevel. This however only applies to the planning of it.

 

True. Coordination can make just about anything possible, provided there's no conflict.

After setting the altitude with the rotary on the MCP, do I need to push it in for it to prompt the VNAV descent?

After setting the altitude with the rotary on the MCP, do I need to push it in for it to prompt the VNAV descent?

 

Nope. Simply pass T/D at the CRZ ALT in the MCP with the MCP ALT below that altitude.