Mach speed not selectable

[adiole757]

In FL 340 and cruising I would like to switch to Mach instead of IAS.

Switching from AT to MACH doenst work. Switching from TM to MACH neither works.

Please see Video. Or did I something wrong?

[iniSteven]

Mach is a pitch mode, not an autothrottle mode. You can only hold a mach speed in cruise with the autothrottle by using "TM" mode through the PMS. The standard AT mode can only hold an indicated airspeed.

[zbrainlezz]

3 minutes ago, iniSteven said:

You can only hold a mach speed in cruise with the autothrottle by using "TM" mode through the PMS.

So then, is it not possible to change the cruise Mach when in TM if needed? For example, if you're on VATSIM and given a cruise speed restriction?

The ability to change the cruise Mach in this mode would be preferable to having to try to use IAS mode to hold a Mach.

[iniSteven]

38 minutes ago, zbrainlezz said:

So then, is it not possible to change the cruise Mach when in TM if needed? For example, if you're on VATSIM and given a cruise speed restriction?

The ability to change the cruise Mach in this mode would be preferable to having to try to use IAS mode to hold a Mach.

As per the real aircraft, the IAS and MACH modes on the MCP are Pitch modes - they will pitch the aircraft to hold a selected IAS or MACH speed while the throttles are operated manually to adjust climb/descent rate.

Again as per the real aircraft, AT mode can only hold an IAS dialed into the window, and TM mode can only hold the Mach value calculated by the PMS. If you want to hold a specific mach value, you have to do it via entering the corresponding IAS in AT mode.