5 hours ago, jarmstro said:

Yes but shouldn't TOD be at a point where the plane descends to the first constraint at throttle idle without the need for constant speed brakes or any thrust?

Much more likely for the descent to be slippery if you have a tailwind. In these situations inputting the descent forecast is very important for a more accurate profile. But alas will still not always be perfect, but on my end, it does the job great.

I did a push, start, take off and climb out the other day before I then realized the fuel tanks were still off. 

 

 

Edited July 31, 20223 yr by flyhalf

59 minutes ago, flyhalf said:

I did a push, start, take off and climb out the other day before I then realized the fuel tanks were still off. 

 

 

I believe you mean the electric fuel pumps. A 737 can be operated perfectly well without electric fuel pumps, the engines are gravity fed.

Edited July 31, 20223 yr by psychedelic_tortilla

Yup and even without the eng driven pumps, the engines will suction feed... up to a certain altitude. 

Re using spoilers in descent, a lot of STARS are constructed more for the convenience of ATC than the aircraft flying them. I had a conversation with a Virgin 787 Captain, he was saying inbound to LAX the spoilers were used for almost the whole descent.

Eugene

Anyone notice the 737 is having problems with banking? I put in a hold in my flight plan and the plane was unable to turn sharp enough to stay in the turn, it was like the bank angle was set to 10 even though it was set to 30. Really strange and haven’t seen that before.

Flying the PMDG 737 Kord to Klga the other day with about a 100 knot tailwind. Watching a real flight on the PFD about 10 miles in front of me (I use psxt, aig, real traffic) it descended in front of me way earlier than I would have thought, my TOD wasn't even in the 40 mile range, it leveled off at 12 thousand for a few minutes probably to stay above the 250 kts. My wife and daughter were on the real flight so I was watching their flight on flight radar 24 and listening to live atc on a tablet which I thought was pretty cool.

More details on VNAV from Emi. 

3 hours ago, bugbee said:

it descended in front of me way earlier than I would have thought, my TOD wasn't even in the 40 mile range, it leveled off at 12 thousand for a few minutes probably to stay above the 250 kts.

Lots of folks on the forums misunderstand the significance of the TOD computed by airliner FMCs. It serves only as an pilot advisory, not as the point to start one's descent. That is determined by enroute/center ATC. Of course, if flying a simulator offline, you can use the TOD to help set where you want to start your descent but when I do so, I always enter the "EXPECT" altitudes into the CDU so as to achieve a reasonably realistic flight path.

In this case, the real world traffic was probably flying the Milton 4 STAR into KLGA.

https://skyvector.com/files/tpp/2207/pdf/00289MILTON.PDF

As noted on the chart, there are several step down fixes at which the flight can "EXPECT" to find itself on the way down. These are set in this case, probably much more by the need to be clear of north-south traffic into and out of KPHL, KIAD, KDCA, and KBWI than it is by the desire to optimize fuel efficiency.

Note that that the MIP4 STAR is not an RNAV STAR for which a "Descend via" clearance will be given. Separate "Descend and Maintain" clearances are required for each of the stepdown fixes at MARRC, BILEY, and BEUTY.

1 hour ago, jrw4 said:

Lots of folks on the forums misunderstand the significance of the TOD computed by airliner FMCs. It serves only as an pilot advisory, not as the point to start one's descent. That is determined by enroute/center ATC. Of course, if flying a simulator offline, you can use the TOD to help set where you want to start your descent but when I do so, I always enter the "EXPECT" altitudes into the CDU so as to achieve a reasonably realistic flight path.

In this case, the real world traffic was probably flying the Milton 4 STAR into KLGA.

https://skyvector.com/files/tpp/2207/pdf/00289MILTON.PDF

As noted on the chart, there are several step down fixes at which the flight can "EXPECT" to find itself on the way down. These are set in this case, probably much more by the need to be clear of north-south traffic into and out of KPHL, KIAD, KDCA, and KBWI than it is by the desire to optimize fuel efficiency.

Note that that the MIP4 STAR is not an RNAV STAR for which a "Descend via" clearance will be given. Separate "Descend and Maintain" clearances are required for each of the stepdown fixes at MARRC, BILEY, and BEUTY.

What's the point of VNAV then? From what you say it's of no practical use? Do RW pilots actually bother with it?

Edited July 31, 20223 yr by jarmstro

6 minutes ago, jarmstro said:

What's the point of VNAV then? From what you say it's of no practical use? Do RW pilots actually bother with it?

They do.  On approach , it's all about energy management and VNAV is a useful reference.  

17 minutes ago, jarmstro said:

From what you say it's of no practical use? Do RW pilots actually bother with it?

It can be useful, both on approach as has been discussed immediately above, and also for those RNAV approaches that permit "Descend via" clearances, where energy management does come in. However, pilots generally do not have discretion to undertake that descent until cleared to do so, and then must begin the maneuver without undue delay. It's also very handy on some SIDs, of course.

The DES NOW button on the Descent page plays a role here as does the dreaded speed brake. Try undertaking early and late descents sometimes, just to see how these things actually work.

30 minutes ago, jrw4 said:

It can be useful, both on approach as has been discussed immediately above, and also for those RNAV approaches that permit "Descend via" clearances, where energy management does come in. However, pilots generally do not have discretion to undertake that descent until cleared to do so, and then must begin the maneuver without undue delay. It's also very handy on some SIDs, of course.

53 minutes ago, jarmstro said:

What's the point of VNAV then? From what you say it's of no practical use? Do RW pilots actually bother with it?

To add to this, VNAV can also be used if you're not flying a SID or a STAR but only following vectors. In this case, VNAV will still guide you through things like initial climb and acceleration height, command FMC speeds like manually entered speeds and econ speeds, max angle etc., the 250 kts restriction below 10000 (or any other entered restriction) and also automatically command flap maneuvering speeds as soon as you retract or extend flaps, etc. Its usage is not limited to set vertical paths like SIDs or STARs with restrictions or even having any lateral route loaded at all. Many airlines have VNAV set as their preferred method for takeoff, regardless of whether an RNAV SID is flown or just vectors to the first fix with no restrictions.

Edited July 31, 20223 yr by threegreen

It seems to me that speedbrake usage is also an airline specific thing. 
I fly Lufthansa and TAROM quite often and they rarely use the speedbrake. 
Could be related to CI also.

But every single Emirates flight I had until now - they dive down like crazy and apply speedbrake almost all the time. Had 6 flights until now with them, A380 and 777-300ER. And it’s always the same. 🙂

Edited July 31, 20223 yr by MySound

18 minutes ago, threegreen said:

automatically command flap maneuvering speeds as soon as you retract or extend flaps

I'm used to this on the Airbus, being in managed speed mode and at the "green dot" speed before going flaps 1. But what about on the -700? If you're in VNAV SPD mode below 10,000, I guess the usual speed is 250 or 240. But you can't go flaps one from that speed? Or, how do you do this in practice?