The F70 Professional and F100 Professional simulate dual Inertial Reference Systems (IRS), which must be aligned prior to flight. The IRS can be aligned by setting the IRS switches on the Mode Select Unit (MSU) to ALN or NAV, entering an initial position into the FMS INIT A page, and then selecting IRS ALIGN. 

The IRS alignment time varies from 3 to 15 minutes based on the aircraft’s latitudinal position. Alignment when the aircraft is close to the equator will be towards the lower end of that timeframe, and alignment with the aircraft at high latitudes will be towards the higher end of that time frame. 

As a quality of life feature, we have provided an IRS ALIGN SPEED option on the Aircraft page of the EFB tablet. This option provides two IRS alignment speeds: 

• REAL: using the aforementioned logic with an alignment time of between 3 and 15 minutes.
• FAST: IRS alignment will occur within 10 seconds of the IRS alignment conditions being met. 

The time-to-go during IRS alignment can be viewed on the ISDU by selecting HDG/STS mode.