9.5 Flight Plan Filing: Domestic and International (ICAO) Flight Plans
Key Takeaways
- Three separate documents govern a Part 121 flight: the company computerized flight plan, the ATC flight plan filed with air traffic control, and the dispatch release required by 14 CFR § 121.687 — and an amendment to one does not amend the others.
- The ICAO format on FAA Form 7233-4 is the standard flight plan format for filing in the National Airspace System, with narrow remaining exceptions such as Department of Defense and civilian stereo route flight plans that still use the FAA Form 7233-1 format.
- Item 10 equipment and capability codes and the Item 18 PBN descriptor are what actually authorize an aircraft onto an RNAV route, an oceanic track, or a reduced-separation airspace; an equipment downgrade changes the eligible routing and therefore changes the fuel.
- Item 19 supplementary information — endurance, persons on board, emergency radio, and survival equipment — is not transmitted with the flight plan but is retained for search and rescue, which is why it must be accurate before departure.
- The AIM advises filing an IFR flight plan at least 30 minutes before the proposed departure time, and a filed flight plan is purged from the ATC computer roughly 2 hours after the proposed departure time unless a revised time is supplied.
9.5 Flight Plan Filing: Domestic and International (ICAO) Flight Plans
Part 65 Appendix A, section VI.D lists Flight Plans (Domestic, International) as a required element of the Air Traffic Control curriculum. It belongs there because the flight plan is the dispatcher's formal request to the air traffic system: it declares what the aircraft is, what it can do, where it is going, and what it will need if something goes wrong.
1. Three Documents That Are Not the Same Document
This distinction is tested and is operationally consequential.
| Document | Who produces it | What it governs | Governing rule |
|---|---|---|---|
| Company (computerized) flight plan | The carrier's flight planning system, authorized by the dispatcher | Route, altitudes, winds, waypoint-by-waypoint fuel and time, payload, performance | Company procedures / GOM |
| ATC flight plan | Filed with air traffic control, normally in ICAO format | How ATC will handle the aircraft: route clearance, separation, strip data, equipment eligibility | FAA flight plan filing procedures / AIM |
| Dispatch release | The dispatcher, with PIC concurrence | The legal authorization to operate: flight number, aircraft, airports, alternates, minimum fuel, weather reports and forecasts | 14 CFR § 121.687 (domestic and flag); § 121.689 (supplemental flight release) |
[!WARNING] Exam trap: refiling or amending an ATC flight plan does not amend the dispatch release. A route, destination, alternate, or fuel change requires an amended release under 14 CFR § 121.631, agreed by the dispatcher and the PIC. Likewise, amending the release does not by itself tell ATC anything — the flight plan must be refiled or amended separately.
2. Which Form: 7233-1 or 7233-4
The FAA has consolidated flight plan filing onto the international (ICAO) format, FAA Form 7233-4, which is now the standard format for filing in the National Airspace System. The older FAA Form 7233-1 domestic format survives only for narrow cases such as Department of Defense flight plans and civilian stereo route flight plans. Any flight departing U.S. domestic airspace files in ICAO format. For a Part 121 dispatcher this means the ICAO form is the working document for essentially every release.
3. The ICAO Flight Plan, Item by Item
| Item | Content | What a dispatcher must get right |
|---|---|---|
| 7 | Aircraft identification | The ATC call sign — the flight number for an airline, not the registration |
| 8 | Flight rules (I, V, Y, Z) and type of flight (S scheduled, N non-scheduled, G general, M military, X other) | Y = IFR first then VFR; Z = VFR first then IFR. Part 121 scheduled service files I and S |
| 9 | Number of aircraft, aircraft type designator, and wake turbulence category | L (light), M (medium), H (heavy), J (super). The category drives ATC separation behind the aircraft |
| 10 | 10a communication, navigation and approach aid equipment and capabilities; 10b surveillance equipment | This is the aircraft's résumé. It determines eligibility for RNAV routes, RVSM airspace, oceanic tracks, CPDLC, and ADS-C/ADS-B services |
| 13 | Departure aerodrome and estimated off-block time (UTC) | The reference time for the purge clock and for slot and EDCT coordination |
| 15 | Cruising speed, requested cruising level, and route | Must use valid route syntax, published fixes and airways, and reflect any organized track system assignment |
| 16 | Destination aerodrome, total estimated elapsed time, and destination alternate(s) | The alternates here are the ATC-facing declaration; the legally required alternates live on the release |
| 18 | Other information: PBN/, DOF/ (date of flight), REG/, EET/, SEL/ (SELCAL code), CODE/, RMK/, RVR/, OPR/ | PBN/ is where navigation specifications are declared; DOF/ is the date-of-flight trap on a UTC date rollover |
| 19 | Supplementary information: endurance, persons on board, emergency radio, survival and life-saving equipment, aircraft color and markings, pilot in command | Not transmitted to ATC with the plan — it is retained by the filing facility for search and rescue (Section 16.5). It must still be accurate |
Wake Turbulence Categories
| Code | Category | Basis |
|---|---|---|
| L | Light | Maximum certificated takeoff mass of 7,000 kg (about 15,500 lb) or less |
| M | Medium | More than 7,000 kg and less than 136,000 kg |
| H | Heavy | 136,000 kg (about 300,000 lb) or more |
| J | Super | The A380 category, with its own increased separation standards |
Why Item 10 and the PBN Descriptor Matter to Fuel
Equipment declarations are not paperwork — they are authorizations. If an aircraft's Item 10 no longer supports the required navigation specification because an FMS, a GNSS receiver, an RVSM altimetry system, or a CPDLC/ADS-C system is deferred on the MEL, the aircraft loses eligibility for the routing that was planned. The consequences ripple straight into the release:
- Loss of RVSM eligibility forces the flight below FL290 or above FL410, raising burn substantially;
- Loss of oceanic data link capability can cost the organized track and force a fixed-track or a longer routing;
- Loss of RNAV capability can force conventional airway routing with a mileage penalty and higher terminal minimums.
A dispatcher who accepts an MEL deferral without asking what it does to Item 10 will discover the problem when ATC rejects the route.
4. Route Validation Before Filing
A legal route is not automatically an acceptable route. Before filing, a dispatcher validates against:
- Preferred IFR routes and Coded Departure Routes (CDRs) — pre-coordinated routings between city pairs that ATC will accept without negotiation.
- Active traffic management initiatives — Ground Delay Programs, Airspace Flow Programs, Ground Stops, reroutes, and "playbook" routes issued for severe weather (Section 9.3). A filed route that ignores an active reroute advisory will be amended by ATC, usually at a fuel cost the release did not plan for.
- Special use airspace and TFR status (Section 9.2).
- Altitude eligibility — RVSM, MEA/MOCA/MAA constraints, and the hemispheric cruising-level rules.
- Organized track system messages — the NAT track message and PACOTS assignments for the relevant crossing period (Section 16.2).
- Destination and alternate acceptance — slots, curfews, customs and immigration hours, and ARFF index.
5. Filing Timing, Amendment, and Purge
- The AIM advises filing an IFR flight plan at least 30 minutes before the proposed departure time so that the clearance is available without delay. International filing is typically done earlier to allow for foreign ATC coordination and slot allocation.
- A filed flight plan is held in the ATC computer and is purged roughly 2 hours after the proposed departure time unless a revised time is supplied. For a long ground delay, the dispatcher must update the proposed time rather than assume the plan is still active.
- Amendments are filed for route, altitude, time, or equipment changes. When the change is material to the operation, amend the release as well under § 121.631.
- Closing the plan matters. An IFR flight plan in controlled airspace is closed automatically on landing at a towered airport; at a non-towered field it must be closed explicitly. An unclosed plan starts the overdue aircraft sequence described in Section 16.5 — a real and avoidable false alarm.
Common ADX Exam Traps
- Treating the ATC flight plan as the dispatch release. Section 121.687 defines the release; the flight plan is an ATC document.
- Putting the legal alternate determination in Item 16. The alternate requirement comes from §§ 121.619, 121.621, or 121.623 and is carried on the release; Item 16 merely declares it to ATC.
- Assuming Item 19 reaches the controller. It does not; it is held for search and rescue.
- Ignoring an MEL's effect on Item 10. An equipment downgrade changes route eligibility and therefore changes fuel.
- Letting a plan purge during a long ground delay. Update the proposed departure time.
An en route flight accepts an ATC amendment that changes its routing and cruising altitude. The dispatcher refiles the ATC flight plan to match. What remains to be done before the flight may legally continue under the new profile?
Maintenance control advises the dispatcher that an aircraft's RVSM altimetry system has been deferred under the MEL for a transatlantic flight originally planned at FL350 on an organized track. What is the dispatcher's correct analysis?
Which statement correctly describes Item 19 of the ICAO flight plan and its operational significance for an aircraft dispatcher?
A flight's proposed departure time was 1400Z, but a lengthy mechanical delay means it will not depart until approximately 1700Z. What should the dispatcher do with respect to the filed ATC flight plan?