Decoding the ICAO flight plan

A filed flight plan tells air traffic control not just where you are going but what your aircraft can do, and most of that capability is packed into two fields that reward learning to read.

This is general educational information, not operational, legal, or regulatory advice. Rules differ by authority and change over time. Always verify against current official sources and follow your operator's approved procedures.

The ICAO flight plan form

The flight plan filed with air traffic services follows the ICAO model form, defined in ICAO Doc 4444 (PANS-ATM), Appendix 2. Its numbered items run from the aircraft identification (Item 7) through the route and times to the supplementary information, and the same form is filed worldwide. In Europe it is processed by the EUROCONTROL Integrated Initial Flight Plan Processing System, whose rules are set out in the IFPS Users Manual; in the United States the same ICAO form is filed as FAA Form 7233-4, with guidance in the FAA AIM, Appendix 4. Two items carry most of the capability information, and they are the ones worth decoding in detail: Item 10 and Item 18.

Item 10: equipment and capabilities

Item 10 describes what the aircraft is fitted with and approved for. It splits at an oblique stroke into two halves.

Item 10a lists communication, navigation, and approach-aid equipment. The EUROCONTROL Flight Plan Guide and FAA Appendix 4 give the letters; the common ones are:

• N no equipment, or it is unserviceable.
• S the standard fit (VHF radiotelephony, VOR, and ILS).
• D DME, G GNSS, F ADF, O VOR.
• R PBN approved, with the specific navigation specifications given in Item 18 under PBN/.

Item 10b lists surveillance equipment, mainly the transponder and any ADS-B. Reading these precisely matters:

• N none; A Mode A transponder; C Mode A and Mode C.
• S Mode S transmitting pressure altitude and aircraft identification; E Mode S with the same plus extended squitter (you file the letter that matches the unit, not several at once).
• B1 ADS-B "out", B2 ADS-B "out" and "in".

Item 18: other information

Item 18 carries everything that does not fit the earlier boxes, written as keyword indicators, each a label followed by an oblique stroke and run together with spaces between. They are entered in the sequence shown in ICAO Doc 4444, and the common indicators are DOF/ (date of flight), PBN/ (the navigation specifications), NAV/, COM/, DAT/, SUR/ (further equipment notes), DEP/ and DEST/, REG/ (registration), EET/ (estimated elapsed times to points or boundaries), SEL/ (SELCAL code), and RMK/ (plain-language remarks).

A worked example

Take an aircraft filing:

Item 10: SDFGR/S

• S standard fit, D DME, F ADF, G GNSS, R PBN approved, all in 10a;
• after the stroke, S in 10b: a Mode S transponder reporting pressure altitude and aircraft identification. An aircraft with ADS-B out would add B1.

Item 18: PBN/B2D2 DOF/260605 REG/GABCD EET/LFFF0035 SEL/ABCD RMK/NIL

• PBN/B2D2 gives the performance-based navigation capabilities (here RNAV using GNSS); the exact two-character codes are defined in ICAO Doc 4444, and PBN/ is required whenever R appears in Item 10a.
• DOF/260605 is the date of flight, 5 June 2026, in year-month-day form.
• REG/GABCD is the aircraft registration, G-ABCD.
• EET/LFFF0035 is an estimated elapsed time of 35 minutes to the Paris flight information region boundary.
• SEL/ABCD is the SELCAL code.
• RMK/NIL is the remarks field, here empty.

Why the codes matter

The equipment and capability codes are not box-ticking. Air traffic systems read Item 10 and Item 18 to decide what an aircraft is eligible for: a performance-based-navigation route or an RNP approach is open only to an aircraft whose filed capability supports it, so under-declaring can cost you a route you could have flown, while claiming a capability the aircraft does not have, or one that is unserviceable, is a misdeclaration. The EUROCONTROL IFPS validates these fields against the requested route at the moment of filing, which is why an Item 10 that disagrees with Item 18, or with the route, is one of the most common reasons a plan is bounced back for correction.

Common pitfalls

• Item 10 and Item 18 must agree. An R in 10a without PBN/ codes in Item 18, or a Z anywhere in Item 10 without the matching NAV/, COM/, or DAT/ detail in Item 18, is a common rejection.
• Surveillance letters are not additive in the old way. File the single letter that matches the transponder fitted (for example S or E), not a string of overlapping codes.
• DOF/ is year-month-day, so 260605 is 5 June 2026, not 6 May.
• The form is the same, the validation is not. EUROCONTROL's IFPS and the FAA apply their own checks, so a plan accepted in one region can be queried in another.

In Pilot EFB

Pilot EFB is a study and planning aid that keeps your weather, NOTAMs, flight time, and logbook in one offline-first place. It does not file flight plans and is not a flight-planning or dispatch system, nor a certified Electronic Flight Bag, so build and file your flight plan through your approved flight-planning provider or the official channel, and use this article to understand what the codes mean rather than as a filing tool. Saved briefings stay readable offline; pulling fresh data needs a connection.