4-Axis A109
The A109LUH has a 4-axis AFCS. We use ALTA and IAS for a non-precision approach (along with either HDG or LNAV). The ALTA mode uses VS, which can be trimmed to a desired value, but still provides altitude protection. In the LUH, ALT is maintained on the pitch channel above 60KIAS unless IAS is also engaged, in which case it automatically changes to the collective channel. If the IAS drops below 60KIAS with only ALT engaged, ALT will again chop to the collective channel.
Instrument flying - 4-axis is the way to go.