Airbus A310 VNAV and FMS

[SPLKA]

Using a Simbrief flightplan and a fully configured loadsheet and FMS, I can't get the plane to use VNAV, that is automaticaly following the different altitudes in the plan. I have to set the altitude via the knob and initiate that via the LVL/CH button on the FCU. My knowledge is still to short to know if this is a normal procedure or that I am missing somewhere?

I know there is no VNAV for CLIMB mode but is it suppose to work during CRUISE flight?

AP, AT/THR, PROFILE and NAV modes are activated. Using latest version of the A310 with only the recommended pushback and radar plugin installed.

Thanks for any advise on this.

 

[AntonBunk]

3 hours ago, SPLKA said:

AP, AT/THR, PROFILE and NAV modes are activated.

If that is the case you should be in VNAV/LNAV. Could you please specify, with "automatically following" do you refer to the aircraft automatically initiating climbs and descends based on what you entered in the FMS?

[SPLKA]

7 hours ago, AntonBunk said:

If that is the case you should be in VNAV/LNAV. Could you please specify, with "automatically following" do you refer to the aircraft automatically initiating climbs and descends based on what you entered in the FMS?

Yes, if my flightplan has differeng altitudes in a leg, I was hoping the aircraft's autopilot system would follow that with climbs or descends. However in my flight the plane will remain on the same altitude as iniitialy set with the ALT knob, eventhough the PROFILE button is activated. 

[iniBuilds]

The A310 has no VNAV on the climb 

[AntonBunk]

12 hours ago, SPLKA said:

Yes, if my flightplan has differeng altitudes in a leg, I was hoping the aircraft's autopilot system would follow that with climbs or descends. However in my flight the plane will remain on the same altitude as iniitialy set with the ALT knob, eventhough the PROFILE button is activated. 

That doesn't work on any aircraft to my knowledge, at leased I don't think it's the encouraged way of operating airliners.* Regardless whether you planned and filed step climbs these will always be requested and approved / disapproved by ATC, so in real life you never want the aircraft to start climbing and descending on its own. Entering step climbs in the FMS allows for a more accurate fuel prediction, but the pilots still have to dial in the new altitude and commence the climb. There are slight differences depending on aircraft type (e.g. the 737 will descend at TOD if you dialed in a lower altitude, *after* having been cleared by atc to descend at pilots discretion; other aircraft in the Airbus Family calculate and alert you for the optimum step climb position..), but the logic is basically the same for all airliners. So you're not doing anything wrong :-) 

While were at it, does any airliner have VNAV in climb and if yes what does that mean? To my knowledge managed climb in all aircraft I know only refers to target airspeed, and the climb rate then is a function of speed and calculated thrust. True?

*if real world pilots would care to elaborate I'd be interested

[SPLKA]

On 8/12/2021 at 10:26 AM, AntonBunk said:

That doesn't work on any aircraft to my knowledge, at leased I don't think it's the encouraged way of operating airliners.* Regardless whether you planned and filed step climbs these will always be requested and approved / disapproved by ATC, so in real life you never want the aircraft to start climbing and descending on its own. Entering step climbs in the FMS allows for a more accurate fuel prediction, but the pilots still have to dial in the new altitude and commence the climb. There are slight differences depending on aircraft type (e.g. the 737 will descend at TOD if you dialed in a lower altitude, *after* having been cleared by atc to descend at pilots discretion; other aircraft in the Airbus Family calculate and alert you for the optimum step climb position..), but the logic is basically the same for all airliners. So you're not doing anything wrong 🙂

While were at it, does any airliner have VNAV in climb and if yes what does that mean? To my knowledge managed climb in all aircraft I know only refers to target airspeed, and the climb rate then is a function of speed and calculated thrust. True?

*if real world pilots would care to elaborate I'd be interested

True, as far as I know. Makes sense about ATC requesting and approving VNAV. However, X-Planes ATC sometimes just doesn't work..😒

I had many issues with the A310 climbing and pitching up way to much. Using the correct loadsheet and aircraft data from the Inibuild manual to calculate the T.O in FLEX mode and accordingly the correct inputs for the FMC.  Plane is correctly trimmed (sometimes values of 1.6 nose down are suggested?) but even then already on the runway wants to pitch up, making it very difficult to follow the center line). And in cruise flight, the speed is controlled by the FMC but any ALT change is manual (which means I have to practice a lot what V/S to set in order to reach the target ALT at the right moment)

But guessing I just have to practice a lot with the A310..

 

[AntonBunk]

14 hours ago, SPLKA said:

X-Planes ATC sometimes just doesn't work

There is no such thing as "ATC" on any standard sim.. Flight Unlimited 2 was an exception, the older ones will remember 😉 I was talking about either flying online on VATSIM or IVAO or maybe using Radar Contact (freeware now, still the best ATC addon in my opinion) or Pilot2ATC. 

As to the trim issues: as soon as you initiate the autopilot trim should be handled by the automation. So when changing altitude in cruise that should not be an issue and level change should do the trick. But I agree, V/S can be better for step climbs, especially if it's only 2000 feet or so. There's a simple rule of thumb: 3000 feet below target altitude it's 3000 feet per minute vertical speed, 2000 when 2 below, 1000 when 1 below. Helps not overshooting the runway and, if step climbing, doesn't call for excessive trust for only half a minute or so. 

[Aleks]

On 8/12/2021 at 4:26 AM, AntonBunk said:

 

 .....does any airliner have VNAV in climb and if yes what does that mean? To my knowledge managed climb in all aircraft I know only refers to target airspeed, and the climb rate then is a function of speed and calculated thrust. True?

*if real world pilots would care to elaborate I'd be interested

VNAV climb does exist.  Eg: 737 LNAV/VNAV buttons on MCP.  However, there are different levels of this.  As an example, in the CRJ or Citation where equipped all that VNAV will do is ensure altitude constraints are met during the climb but thrust management is still up to the pilot.