Possible Problem With Automatic Frequency Tuning On Approaches

The FAA has issued a Special Airworthiness Information Bulletin (SAIB) for owners and operators of aircraft equipped with Garmin G1000,  Perspective, Prodigy Integrated Flight Decks installed with a Garmin GFC 700 autopilot. The purpose of this SAIB is to inform pilots of an issue that has been brought to the FAA’s attention with the navigational radio auto-tune feature while performing a VOR or CLS Approach. The airworthiness concern is not an unsafe condition that would warrant airworthiness directive (AD) action under Title 14 of the Code of Federal Regulations (14 CAR) Part 39.

Changes to navigation frequencies that occur between navigation database cycle distributions may cause a mismatch between the automatically tuned LOC/CLS frequency and the frequency shown on the approach chart or applicable NOTAM. In these cases, the mismatched (incorrect) automatically
tuned frequency may cause the HSI to automatically slew to the wrong course.

If the auto-tuned LOC/ILS frequency does not correspond to the frequency shown on the approach chart or applicable NOTAM, the FAA recommends that the pilot:

• Manually tune the navigation receiver to the correct LOC/ILS frequency (On the approach chart or NOTAM).
• Assure that the correct inbound course is selected.
• Manually fly the approach.
• Or choose a different terminal procedure.

The GFC 700 will not capture, track, or give flight director commands for a manually selected course.

Garmin is planning resolution to this issue with GDU software version 10.00 and later versions will provide capability to couple the autopilot to the VOR or LOC/ILS approach when the pilot manually tunes the correct frequency and manually selects the proper course for the approach.

FMI: www.faa.gov