Definition
An FAA Advisory Circular that establishes the criteria and process by which the FAA approves Aviation Training Devices (ATDs), and that defines how time and tasks performed in approved ATDs may be credited toward pilot training, certification, and recent flight experience requirements under 14 CFR Part 61.
Plain English
An FAA guidance document that says how ground-based training devices (the simulator-style trainers that aren't full simulators) get approved, and how time you log in them counts toward your training and currency.
Context Anchor
Seen in discussions of flight simulation training devices, especially when an instructor or school needs to know what simulator or training-device time can be credited.
Derivation
Advisory Circulars are numbered by FAA subject area. The '61' refers to 14 CFR Part 61, the regulations covering pilot certification. The '136' is the sequential number within that subject series. Knowing this tells you immediately that the document deals with pilot certification rules rather than aircraft, airspace, or operations.
Why Pilots Care
If a pilot wants logged ATD time to count toward a rating or toward instrument currency, the device must be FAA-approved under this AC and the time must be logged according to its rules. Using a non-approved device, or logging incorrectly, means the time does not count.
Intuition Check
“Advisory” does not mean “ignore it.” An Advisory Circular is not a regulation by itself, but it is official FAA guidance on how the FAA expects the related rules to be understood and applied.
Example Sentence 1
The flight school's basic aviation training device is approved under AC 61-136, so students can log up to 10 hours of instrument training time in it toward the instrument rating.
Example Sentence 2
Training providers follow AC 61-136 when qualifying devices for instrument or commercial pilot courses.