AIM ¶ 5-1-12 — Flight Plan Changes
AIM 5-1-12 explains when to notify ATC of flight plan changes, including the 5%/10-knot speed rule and the 46-minute revision cutoff for pilots.
In Plain English
AIM 5-1-12 tells you when and how to update an existing flight plan. A change isn't just a new destination or altitude — a speed change counts too.
Key points:
- Notify ATC any time your average true airspeed (TAS) at cruise between reporting points varies (or is expected to vary) from your filed value by ±5% or 10 knots, whichever is greater.
- Other changes that require updating the flight plan include altitude/flight level, destination, and route.
- Make changes more than 46 minutes before proposed departure through your initial flight plan service provider (e.g., the vendor you filed with).
- If that provider is unavailable, you may contact an ATC facility or FSS to revise the plan.
- Any revision made 46 minutes or less before proposed departure must be coordinated through an ATC facility or FSS — not the original filing vendor.
Why it matters: ATC uses your filed data for separation, search-and-rescue timing, and traffic flow. An accurate flight plan keeps controllers' expectations matched to your actual flight profile.
AIM Source Text
FAA AIM ¶ 5-1-125-1-12. 5-1-12. Change in Flight Plan
In addition to altitude or flight level, destination and/or route changes, increasing or decreasing the speed of an aircraft constitutes a change in a flight plan. Therefore, at any time the average true airspeed at cruising altitude between reporting points varies or is expected to vary from that given in the flight plan by plus or minus 5 percent, or 10 knots, whichever is greater, ATC should be advised. All changes to existing flight plans should be completed more than 46 minutes prior to the proposed departure time. Changes must be made with the initial flight plan service provider. If the initial flight plan's service provider is unavailable, filers may contact an ATC facility or FSS to make the necessary revisions. Any revision 46 minutes or less from the proposed departure time must be coordinated through an ATC facility or FSS.
Oral Exam Questions a DPE Might Ask
Q1Besides altitude, destination, or route, what else constitutes a change to a flight plan?
Per AIM 5-1-12, increasing or decreasing the aircraft's speed also constitutes a flight plan change. ATC should be advised any time the average true airspeed at cruising altitude between reporting points varies, or is expected to vary, from the filed value by ±5% or 10 knots, whichever is greater.
Q2When and how should you make changes to an existing flight plan before departure?
Per AIM 5-1-12, all changes should be completed more than 46 minutes prior to the proposed departure time, and must be made with the initial flight plan service provider. If that provider is unavailable, the filer may contact an ATC facility or FSS to make the revisions.
Q3What if you need to revise your flight plan within 46 minutes of departure?
Per AIM 5-1-12, any revision made 46 minutes or less prior to the proposed departure time must be coordinated through an ATC facility or FSS, rather than through the original flight plan service provider.
Related Paragraphs in AIM Chapter 5