I’m familiar enough with the a/p modes for Airbus, Boeing, and the CRJ to know what most do. But I’m curious what SOPs / rules folks use in deciding which modes to use and when for climbs and descents?
Obviously, it depends on the a/c, the add-on / mod and it’s current capabilities, procedures, atc instructions, etc. But I’m wondering if folks follow any particular rules when deciding between vnav (if available), level change/open climb/descent, v/s, etc
Generally, I’ll use vnav if possible, if not then level change/open climb/descent, and if that’s not cutting it, go to v/s.
Otherwise, climb with FLC at 250 below 10000, then switch to VS and dial it back 1/3 to 1/2 to allow speed to pick up, and at climb speed switch back to FLC.
Decent on VS to have a smooth profile down as pressure changes back and can do weird things at FLC
Usually VNAV in real life if / when available whole flight from acceleration altitude to glide slope intercept. Otherwise FLCH during climb and FPA or FLCH or VS during descent.
In order to not exceed 2000 fpm when within 2000 ft from level-off and 1000 fpm when within 1000 ft from level-off its common to select VS. I believe ICAO and Eurocontrol specify 1500 fpm when within 1500 ft during climb and descent to prevent TCAS RAs caused by high vertical rates. Most airlines I’ve worked for use 2000/2000, 1000/1000.
On some turboprops without autothrottle I have flown, FLCH works rubbish during descent as the FD tries to chase airspeed when changing throttle settings. We often used VS instead as a standard and controlled speed with throttle. You could use any other mode during climb or descent, although during climb anything other than speed based (FLCH or VNAV) is not recommended, especially in icing conditions.
I like using FPA on descent, using the A32NX mod, I use the EFB to calculate where my TOD is based on a 3 degree descent angle. Let it sync with the aircraft Ground Speed, and current Altitude, and set my target altitude with the runway elevation. Then it’ll tell me at which distance when I should start my descent.
Then I switch to FPA/TRK mode, and I set to descent at -3.0º and it manages its V/S variably as long as it’s in a -3º descent angle.
There is not much to calculate though, 3 nm per 1000 ft + 2 nm per 10 kts (1 nm per 10 kts in level flight) for deceleration from 250 kts to 180 / 160 kts and done. Works fine in real life as well.
Climb:
VFLC at 250 below 10000, and then VFLC at 290 until cruise. Then let VNAV do the rest for descent
If no VNAV then same FLC for climb and v/s for descent adjusting speed as necessary. NAV/LNAV mode on the whole flight unless ATC gives you vectors, then heading mode until directed to resume own navigation/direct to/intercept localizer.
VNAV can accomplish exactly this when FMS is properly programmed before flight, including adhering to 250 kts below 10.000 ft and transition to MACH at crossover altitude. No need to use FLCH during climb.
Edit: I see you wrote VFLCH, which is a VNAV submode, I guess we mean the same.
Do you really need to switch to VS in order to increase speed during climb or is this a MSFS workaround? In real life there is no need for this, could just select the new speed and AP should do the rest.
On a jet with autothrottle FLCH should work fine during descent, even without autothrottle idle descent should work fine. On turboprops without autothrottle FLCH often works rubbish during descent, its often better to use VS instead.
On the CRJ and CJ4, when you do that, it will first go back to a vs of 0, let speed pick up and then pitches up to keep speed. Kinda aggressive coming from a 2500-3000ft climb
Yeah doubt it would do that in real life, never flew the CRJ or CJ4, I have flown aircraft with similar avionics though and it was no problem with those. Really basic autopilot systems have that kind of behaviour, the ATR -500 for example has the same problem upon speed changes.
What is the difference between VNAV and FLCHG? I know what VNAV is for IRL but I just have major issue translating that to MSF lol. So I have always used FLCHG, looking to be enlightened!
The most important benefit during both VNAV climb and descent and the main reason for using VNAV whenever possible is that it will automatically adhere to all altitude and speed constraint in departure and arrival procedures. Whereas FLCH will maintain whatever speed is set by the pilot and will only level off at the preselected altitude.
During climb VNAV is basically the same as FLCH, difference would be that it automatically changes speed in accordance with what is programmed in the FMS. So automatically maintaining 250 kts below 10.000 ft, increasing above until crossover altitude at which automatic changeover to MACH occurs.
During descent it has more options, idle descent while maintaining speed (basically the same as FLCH) or path descent during which the AP maintains a particular descent path (3 degrees for example), depending on what is programmed or required to fly a particular procedure.
Yea I have never had luck with it in MSF but having read what you wrote, I am guessing is cause I still don’t know how to do much in the Flight computer yet lol.
.