Flew out of KDTW. The first two waypoints on the KAYLN3 SID required you stay below 7,000 and 9,000 respectively. In my case, for the first waypoint, the jet maintained a high rate of climb and then leveled out at 7,000 5 miles before the way point. Did the same for the next one.

Is that the way VNAV works in RL? I would have thought it was supposed to calculate a gradual climb instead of leveling off miles before the crossing points.

Yes, this is how the real airplane works.

Jets are more efficient the higher they fly, so you want to get as high as possible as soon as possible. So it's better to climb with a high rate, then level off, rather than climbing with a lower rate.

11 hours ago, 11bee said:

Flew out of KDTW. The first two waypoints on the KAYLN3 SID required you stay below 7,000 and 9,000 respectively. In my case, for the first waypoint, the jet maintained a high rate of climb and then leveled out at 7,000 5 miles before the way point. Did the same for the next one.

Is that the way VNAV works in RL? I would have thought it was supposed to calculate a gradual climb instead of leveling off miles before the crossing points.

In the real world you would switch over to VS mode once reaching 7000 in order to not climb with full power for 5 more seconds and then level off at 9000, which would feel kind of stupid and also can potentially cause fear with passengers ("Oh my god the engines have failed!").

The A320 shows you where you level off with the current climb rate, so you can perfectly dial in the VS to reach 9000 right at the restriction.

👍

As Graeme of Reflected Reality Simulations likes to say: "VS is for finesse."

Out of LGIR>LIRN today managed flight would not happen I had to use VS mode in the A320CFM, and this is the first time this has happened out of hundreds of flights. Why might that have been?

Cheers

Edited Sunday at 04:16 PM4 days by Noel

6 minutes ago, Noel said:

Out of LGIR>LIRN today managed flight would not happen I had to use VS mode in the A320CFM, and this is the first time this has happened out of hundreds of flights. Why might that have been?

Cheers

The most common reason is not being in NAV mode laterally.

Failing that, here is the complete set of managed CLB engagement criteria (source):

The CLB mode can be engaged when:

• the aircraft has been in flight for more than 5 seconds

• the altitude selected in the FCU is above the current altitude

• not in descent, approach, or go-around phase

• Lateral navigation (NAV) is engaged

• Not in G/S mode

Interesting thanks. Was in NAV mode and everything else seems compliant with those criteria. Perhaps just a bogus initialization.

I think the VNAV still needs some adjustments, especially when reaching the Deceleration Point: the aircraft starts reducing speed but at the same time stops descending and loses the descent path completely, whereas the Ini A350 stays on the descent path while slowing down.

1 minute ago, Ricardo Andrada said:

I think the VNAV still needs some adjustments, especially when reaching the Deceleration Point: the aircraft starts reducing speed but at the same time stops descending and loses the descent path completely, whereas the Ini A350 stays on the descent path while slowing down.

And I think you need to review the way you operate the aircraft. ;)

If it asks for speed brakes it is not optional and you are expected to extend them to half.

I have never once had a problem with the new VNAV keeping me on path.

47 minutes ago, Farlis said:

And I think you need to review the way you operate the aircraft. ;)

If it asks for speed brakes it is not optional and you are expected to extend them to half.

I have never once had a problem with the new VNAV keeping me on path.

Only try out the A350’s VNAV

1 hour ago, Ricardo Andrada said:

I think the VNAV still needs some adjustments, especially when reaching the Deceleration Point: the aircraft starts reducing speed but at the same time stops descending and loses the descent path completely, whereas the Ini A350 stays on the descent path while slowing down.

This is what the narrow body does. Correct behaviour. Comparing to an A350 which is more upgraded.

41 minutes ago, carlanthony24 said:

This is what the narrow body does. Correct behaviour. Comparing to an A350 which is more upgraded.

Could you point to the technical source that supports this conclusion? Is there any official documentation, such as the FCOM, FCTM, or manufacturer training material, showing that this behavior is expected for narrow-body aircraft? And, considering that the A350 incorporates more modern automation technologies and logic, what technical parameters justify this difference in behavior between the aircraft?

35 minutes ago, Ricardo Andrada said:

Could you point to the technical source that supports this conclusion? Is there any official documentation, such as the FCOM, FCTM, or manufacturer training material, showing that this behavior is expected for narrow-body aircraft? And, considering that the A350 incorporates more modern automation technologies and logic, what technical parameters justify this difference in behavior between the aircraft?

FCOM DSC-22-30-50: Profile / Speed Conflict Logic

The aircraft leaves the geometric profile to maintain the speed limit.

As a consequence, the aircraft tends to fly above the vertical profile.

The V/DEV (Vertical Deviation) symbol on the PFD will drift from the center, and the advisory message MORE DRAG appears on the PFD.

A321 Auto Flight Guidance Manual | PDF | Flight | Takeoff

You can find more information on this fcom won't let me copy extracts without making an account.

You can also watch the Video that Fenix released before V3 came out and go the VNAV portion. Amir explains the different ways Thales and Honeywell equipped Airbus aircraft behave.

Edited Monday at 11:02 PM3 days by Farlis

15 hours ago, Ricardo Andrada said:

I think the VNAV still needs some adjustments, especially when reaching the Deceleration Point: the aircraft starts reducing speed but at the same time stops descending and loses the descent path completely, whereas the Ini A350 stays on the descent path while slowing down.

There is a whole 45 minute section on VNAV in the video we released on the Fenix YouTube channel.

The A320 is not an A350. They do not do the same things in a managed descent. The model and equipment fitout on the A320 we have modelled could not be further from the behaviour on the real A350.

Levelling off at a deceleration point is a major feature of the A320's VNAV in the guise we have built it. You may be unfamiliar with it as afaik no one else simulating an A320 has gone this deep on their respective suites. I would highly recommend familiarising yourself with the aircraft before suggesting it needs to be adjusted :D