General (ICAO)

ICAO Annex 2 §3.3 and ICAO Doc 4444 PANS-ATM Appendix 2 govern the Flight Plan (FPL).

A flight plan is specified information provided to ATS units regarding an intended flight or portion of a flight. It serves:

traffic management in controlled airspace,
SAR alerting in case of missing or distressed aircraft,
border control (customs/immigration),
central flow management in Europe (via IFPS at EUROCONTROL).

Europe (EASA / EU)

SERA.4001 (Submission of a flight plan) sets out when a flight plan is mandatory:

FPL submission required (SERA.4001(b)):

Every IFR flight,
VFR flights crossing international borders,
VFR flights at night outside the aerodrome traffic pattern,
VFR flights in airspace where a flight plan is required by the competent authority (e.g. Class C, certain TMAs),
VFR flights for which national rules require a FPL.

Submission timing (SERA.4001(c)):

Before departure to an ATS reporting office,
at least 60 minutes before EOBT (Estimated Off-Block Time),
for flights over ocean/remote areas: 3 hours before EOBT.

Through IFPS (EUROCONTROL) the FPL is electronically forwarded to all relevant ATS units along the route.

FPL content (Doc 4444 Appendix 2, fields 7–19):

Field 7: Aircraft Identification (callsign or registration),
Field 8: Flight Rules (I/V/Y/Z) and Type of Flight (G/S/N/M/X),
Field 9: Number, Type, Wake Turbulence Category (e.g. 1/C172/L),
Field 10: Equipment and Capabilities (e.g. SDFGRY/S),
Field 13: Departure Aerodrome and EOBT,
Field 15: Cruising Speed, Level, Route,
Field 16: Destination Aerodrome, Total EET, Alternates,
Field 18: Other Information (e.g. PBN, DOF, EET, OPR, RMK),
Field 19: Supplementary Information (endurance, POB, survival/emergency equipment, PIC name).

Changes/delays (SERA.4010): Delays exceeding 30 minutes must be communicated to the ATS unit (DLA message); route changes via CHG message.

Closing the FPL (SERA.4020):

IFR: automatically closed by ATC on landing.
VFR at an aerodrome with ATS: automatic.
VFR at an aerodrome without ATS: the pilot must actively close the FPL (e.g. by phone with the nearest ARO/AIS unit); otherwise the SAR mechanism is activated 30 min after ETA (INCERFA → ALERFA → DETRESFA).

Germany (national)

ATS reporting offices: DFS-AIS-C in Frankfurt; FPL submission via online portal (Homebriefing) or phone. The FPL obligation in Germany fully meets the EU requirements; Night VFR and international VFR always require an FPL.

Key rule: A pilot who has filed a VFR FPL and does not reach the destination without ATS must close the FPL — otherwise unnecessary SAR launches occur (the cost may be recovered).