FPL Validation — Design Document

EventFplSvc — ICAO Flight Plan Validation Engine
Based on source analysis of EventFplSvc (.NET/C#) and ICAO PANS-ATM Appendix 2
R-SYS s.r.o. — Author: Peter Kotian

1. System Overview

2. Architecture

Key Components

Data Models

3. Validation Flow

Component	File	Responsibility
`FplValidateJob`	Jobs/FplValidateJob.cs	Main validation orchestrator — coordinates all field checks
`RegexChecker`	Validation/RegexChecker.cs	Centralized regex pattern matching with timeout protection
`OtherInfoChecker`	Validation/OtherInfoChecker.cs	F18 indicator parsing and validation
`FlightRouteChecker`	Validation/FlightRouteChecker.cs	Route string parsing and validation (F15e)
`SupplementaryInfoChecker`	Validation/SupplementaryInfoChecker.cs	F19 supplementary data validation
`ValidationConfig`	Validation/ValidationConfig.cs	Configuration: project variant, limits, feature flags
`ValidationSelection`	Validation/ValidationSelection.cs	Selective validation — choose which fields to validate
`AisGisClient`	Validation/AisGisClient.cs	External AIS/GIS interface for aerodrome and route verification
`PatternChecker`	(Comm library)	Shared ASCII pattern checking, enum parsing utilities

Model	Purpose
`FplValidate`	Strongly-typed FPL model (uses enums — throws on invalid values)
`FplValidateWeak`	Weakly-typed model (uses strings instead of enums — allows meaningful error messages for invalid values)
`Equipment`	COM/NAV (F10a), SSR (F10b), ADS (F10c) equipment
`CruisingSpeed`	Speed unit + value (F15a/b)
`FlightLevel`	Level unit + value (F15c/d)
`SupplementaryInfo`	F19 endurance, persons, survival, dinghies, PIC, etc.
`AdditionalInfo`	Pilot/sender contact details
`ListMessages`	Collects errors and warnings with message codes

FplValidateJob.Validate(fpl, customSelection, ct) │ ├─ Clear() — reset state │ ├─ Pre-parse F18 — OtherInfoChecker.Check() │ Parse indicators from F18 other info text │ Store in dictIndicators for cross-checks later │ ├─ F7 Aircraft ID ─── ^[A-Z0-9]{1,7}$ ├─ F8a Flight Rules ─── I | V | Y | Z ├─ F8b Flight Type ─── S | N | G | M | X ├─ F9a Number of Aircraft ─── 2–99 (if present) ├─ F9b Aircraft Type ─── ^[A-Z][A-Z0-9]{1,3}$ │ ├─ ZZZZ → must have TYP/ in F18 │ ├─ not ZZZZ → must NOT have TYP/ in F18 │ └─ not special → DB lookup for WTC verification ├─ F9c Wake Turbulence ─── L | M | H | J (+ DB cross-check) │ ├─ F10a COM/NAV Equipment ─── regex + Y/Z cross-checks ├─ F10b SSR Equipment ─── regex + mutual exclusion (I,P,X) ├─ F10c ADS Equipment ─── regex (if SSR has ADS indicators) │ ├─ F13b EOBT ─── time window: [latestEobt, earliestEobt] ├─ F15a Speed Unit ─── K | N | M ├─ F15b Speed Value ─── 3 or 4 digits (M=3, K/N=4) ├─ F15c Flight Level Unit ─── F | A | S | M | VFR ├─ F15d Flight Level Value ─── 3 digits (F/A) or 4 digits (S/M) │ ├─ F15e Route ─── full or basic check │ ├─ HU variant: basic check only │ ├─ AIS/GIS route validation (if enabled) │ └─ Local regex-based route parsing (fallback) │ ├─ F13a ADEP ─── 4-char ICAO code or ZZZZ/AFIL ├─ F16a ADES ─── 4-char ICAO code or ZZZZ ├─ F16b Total EET ─── must be > 0 ├─ F16c ALT Aerodrome ─── 4-char ICAO code or ZZZZ ├─ F16d 2nd ALT Aerodrome ─── 4-char ICAO code or ZZZZ │ ├─ F18 Other Info ─── indicator validation + cross-checks │ ├─ PBN vs F10a cross-check │ ├─ EET required if crossing FIR boundaries │ ├─ STAYINFO required if route has STAY markers │ ├─ RMK/PHONE mandatory (configurable) │ └─ OPR mandatory (configurable) │ ├─ F19 Supplementary Info ─── endurance, persons, PIC, survival, etc. │ └─ Additional Info ─── pilot/sender contact validation Result: errors.Count == 0 → valid Result: errors.Count > 0 → invalid (errors + warnings returned)

4. Field-by-Field Validations

Aircraft Identification

Max 7 alphanumeric characters
Pattern: ^[A-Z0-9]{1,7}$
No hyphens or symbols
Examples: KLM511, EIAKO, N2567GA

F8a

Flight Rules

I — entire flight IFR
V — entire flight VFR
Y — initially IFR, then changes
Z — initially VFR, then changes
Cross-checked with flight level (VFR cannot use IFR level)

F8b

Type of Flight

S — scheduled air service
N — non-scheduled air transport
G — general aviation
M — military
X — other

F9a

Number of Aircraft

Range: 2–99 (if present)
Omitted for single aircraft

F9b

Type of Aircraft

Pattern: ^[A-Z][A-Z0-9]{1,3}$
ZZZZ → requires TYP/ in F18
Non-ZZZZ → must NOT have TYP/ in F18
Non-special types verified against IBAF database
Special designators: GLID, balloons, etc. (configurable)

F9c

Wake Turbulence Category

L — Light (≤7000kg)
M — Medium (7000–136000kg)
H — Heavy (≥136000kg)
J — Super (A380-800, AN-225)
Cross-checked with database WTC for aircraft type

F10a

COM/NAV Equipment

Validated by regex (complex pattern)
R → must have PBN/ in F18
Z → must have COM/, DAT/, or NAV/ in F18
Y (8.33 kHz) — mandatory based on config
EXM833 exemption: Z required, Y forbidden

F10b/c

SSR & ADS Equipment

N — no SSR transponder (standalone, no ADS)
I, P, X — mutually exclusive modes
I/P/X excludes E, H, L, S
ADS validated separately if present

F13a

Departure Aerodrome

4-character ICAO code
ZZZZ → requires DEP/ in F18 with coordinates
AFIL → airfiled flight plan (special handling)
Non-special codes validated against AIS/GIS (if enabled)

F13b

EOBT (Estimated Off-Block Time)

Must be in the future
IFR: between [latestIfrEobt, earliestIfrEobt] from now
VFR: between [latestVfrEobt, earliestVfrEobt] from now
SK/PL/NL: warning if filed too close to EOBT
Default: earliest=5 days, latest=1 hour

F15a/b

Cruising Speed

Unit: K (km/h), N (knots), M (Mach)
Value: 4 digits for K/N, 3 digits for M
Examples: N0450, K0830, M082

F15c/d

Cruising Level

F (flight level): 3 digits (F350)
A (altitude): 3 digits (A045)
S (metric level): 4 digits (S1130)
M (metric altitude): 4 digits (M0840)
VFR — no value (cannot be used with IFR/Y flight rules)

F15e

Route

Length: 2–1000 characters
Parsed for waypoints, routes, speed/level changes
Y rules: must contain VFR indicator
Z rules: must contain IFR indicator
VFR: DCT first and last (configurable)
AIS/GIS validation when available

F16a

Destination Aerodrome

4-character ICAO code
ZZZZ → requires DEST/ in F18 with coordinates
Validated against AIS/GIS if enabled

F16b

Total Estimated Elapsed Time

Must be greater than 0
4-figure format (HHMM)

F16c/d

Alternate Aerodromes

4-character ICAO code (optional)
ZZZZ → requires ALTN/ in F18 with coordinates
Count of ZZZZ aerodromes must match LAT/LON entries in ALTN/
Validated against AIS/GIS if enabled

F19

Supplementary Information

Endurance: HHMM format, must ≥ Total EET (except GLID)
Persons on Board: 1–999 or "TBN"
Aircraft Colour: uppercase, max 300 chars
PIC: uppercase, max 50 chars, phone optional
Emergency Radio: U/V/E combinations
Survival: P/D/M/J combinations
Jackets: L/F/U/V combinations
Dinghies: number, capacity, colour (all mandatory if present)

5. Cross-Field Checks

Check	Fields	Rule
CROSS PBN ↔ Equipment	F10a ↔ F18	If `R` in F10a → must have `PBN/` in F18 (max 8 items). Each PBN marker (B1–T2) requires specific F10a indicators (D, G, I, O, S).
CROSS Type ↔ TYP/	F9b ↔ F18	If F9b = `ZZZZ` → must have `TYP/` in F18. If F9b ≠ `ZZZZ` → must NOT have `TYP/`.
CROSS ADEP ↔ DEP/	F13a ↔ F18	If ADEP = `ZZZZ`/`AFIL` → must have `DEP/` in F18 with LAT/LON coordinates. If normal ICAO code → must NOT have `DEP/`.
CROSS ADES ↔ DEST/	F16a ↔ F18	If ADES = `ZZZZ` → must have `DEST/` in F18 with LAT/LON coordinates. If normal ICAO code → must NOT have `DEST/`.
CROSS ALTN ↔ ALTN/	F16c/d ↔ F18	Each `ZZZZ` alternate requires a corresponding LAT/LON coordinate pair in F18 `ALTN/`.
CROSS Z ↔ COM/DAT/NAV	F10a ↔ F18	If `Z` in F10a → must have `COM/`, `DAT/`, or `NAV/` in F18.
CROSS EXM833 ↔ Equipment	F18 ↔ F10a	If `COM/EXM833` in F18 → `Z` required in F10a, `Y` forbidden.
CROSS Flight Rules ↔ Level	F8a ↔ F15c	IFR or Y flight rules cannot use `VFR` flight level.
CROSS Flight Rules ↔ Route	F8a ↔ F15e	Y rules → route must contain `VFR`. Z rules → route must contain `IFR`.
CROSS EET ↔ FIR crossing	F18 ↔ F13a/F16a	If VFR and ADEP/ADES in different countries (first 2 chars differ) → `EET/` required in F18.
CROSS Endurance ↔ EET	F19a ↔ F16b	Endurance must be ≥ Total EET (except for GLID aircraft type).
CROSS WTC ↔ Database	F9c ↔ IBAF DB	Wake turbulence category cross-checked with aircraft type database lookup.
CROSS STAYINFO	F15e ↔ F18	If route contains STAY markers → `STAYINFO` required in F18.

6. F18 Other Information Indicators

F18 is a free-text field containing structured indicators in the format INDICATOR/value. The system parses these indicators and validates both their syntax and cross-references with other fields.

Indicator	Description	Validation
STS/	Flight status (FFR, HOSP, MEDEVAC, SAR, STATE, etc.)	Valid status values, affects Y-mandatory exemption
PBN/	PBN capabilities	Max 8 items, cross-checked with F10a equipment
NAV/	Navigation equipment details	Required if Z in F10a
COM/	Communication equipment details	Required if Z in F10a, EXM833 special handling
DAT/	Data link equipment	Required if Z in F10a
TYP/	Aircraft type (for ZZZZ)	Required iff F9b = ZZZZ
DEP/	Departure aerodrome (for ZZZZ/AFIL)	Required iff F13a = ZZZZ/AFIL, must have LAT/LON
DEST/	Destination aerodrome (for ZZZZ)	Required iff F16a = ZZZZ, must have LAT/LON
ALTN/	Alternate aerodromes (for ZZZZ)	LAT/LON count must match ZZZZ alternates count
EET/	Estimated elapsed time at FIR boundaries	Required if VFR crossing FIR boundaries
RMK/	Remarks	PHONE mandatory (configurable)
OPR/	Operator	Mandatory (configurable)
DOF/	Date of flight	NOT allowed (rejected)
EUR/	European indicator	PROTECTED value handling
ORGN/	Originator	Syntax check
REG/	Registration	Syntax check
SEL/	SELCAL code	Syntax check
RALT/	En-route alternate	Aerodrome code syntax
TALT/	Take-off alternate	Aerodrome code syntax
RIF/	Reclearance in flight	Syntax check
RVR/	RVR value	Numeric
CODE/	Mode S code	Hex format
DLE/	Delay en-route	Syntax check
STAYINFO	Stay information	Required if route has STAY markers

Indicator Parsing Rules

Indicators separated by spaces
Format: INDICATOR/value (no space between indicator and slash)
Only AFTN-safe characters allowed in entire F18 text
No duplicate indicators (each may appear only once)
Unknown indicators are flagged as errors

7. External Validation (AIS/GIS)

8. Configuration

Parameter	Default	Description
ProjectVersion	—	Country variant: SK, HU, PL, NL
F10_Y_Mandatory	—	8.33 kHz equipment: NO / IFR / YES
OherInfoOprMandatory	false	F18 OPR/ indicator mandatory
OherInfoRmkPhoneMandatory	false	F18 RMK/ must contain phone number
PicPhoneMandatory	false	F19 PIC must contain phone number
AddInfoPilotTelMandatory	false	Additional info pilot telephone mandatory
AisGisAdValidation	false	Enable AIS/GIS aerodrome validation
AisGisRouteValidation	false	Enable AIS/GIS route validation
VfrRouteFirstLastDCT	false	VFR routes must start and end with DCT
SpecialArcTypes	—	CSV list of special aircraft types (GLID, balloons, etc.)
LATEST_IFR_EOBT	1H	Latest time to file before IFR EOBT
LATEST_VFR_EOBT	1H	Latest time to file before VFR EOBT
EARLIEST_IFR_EOBT	120H	Earliest time to file before IFR EOBT
EARLIEST_VFR_EOBT	120H	Earliest time to file before VFR EOBT
Email	—	Regex for email validation
PhoneNr	—	Regex for phone number validation
ConnStringIbaf	—	SQL Server connection for aircraft type DB
AisGISInterfaceURL	—	SOAP endpoint for AIS/GIS service

EOBT Time Format

Uses PHP DateInterval-like syntax: 30M = 30 min, 1H = 1 hour, 1H30M = 90 min.

9. Project Variants

10. Error Message Catalog

Variant	Differences
`SK` (Slovakia)	EOBT warning if filed too close (instead of error) Full route validation with AIS/GIS
`HU` (Hungary)	Basic route checks only (no full parsing) Simplified Y/Z flight rules check on route
`PL` (Poland)	EOBT warning if filed too close (same as SK) Full route validation
`NL` (Netherlands)	EOBT warning if filed too close (same as SK/PL) Full route validation

Code	Field	Message	Type
`FplFormErr_arcid`	F7	Invalid Aircraft Identification	ERROR
`FplFormErr_fr`	F8a	Invalid Flight Rules	ERROR
`FplFormErr_fr_flvlv`	F8a	Flight Rules not compliant with VFR Flight Level	ERROR
`FplFormErr_fltype`	F8b	Invalid Type of Flight	ERROR
`FplFormErr_numberAcs`	F9a	Invalid Number of Aircrafts	ERROR
`FplFormErr_atype`	F9b	Invalid Type of Aircraft	ERROR
`FplFormErr_wtc`	F9c	Invalid Wake Turbulence Category	ERROR
`FplFormErr_equip1`	F10a	Invalid Equipment	ERROR
`FplFormErr_equip1_ZReq`	F10a	Z is required	ERROR
`FplFormErr_equip1_YReq`	F10a	Y is required	ERROR
`FplFormErr_equip1_exm833`	F10a	EXM833 exemption: Y not allowed	ERROR
`FplFormErr_equip2`	F10b	Invalid SSR Equipment	ERROR
`FplFormErr_equip2_IPX`	F10b	I, P, X mutually exclusive	ERROR
`FplFormErr_equip2_EHLS`	F10b	I/P/X excludes E,H,L,S	ERROR
`FplFormErr_equip3`	F10c	Invalid ADS Equipment	ERROR
`FplFormErr_adep_invalid`	F13a	Invalid Departure Aerodrome	ERROR
`FplFormErr_eobdt_invalid`	F13b	Invalid EOBT	ERROR
`FplFormErr_eobdt_between`	F13b	EOBT must be between {0}, {1}	ERROR
`FplFormErr_eobdt_least`	F13b	FPL should be filed at least {0} before EOBT	WARN
`FplFormErr_speedm_invalid`	F15a	Invalid Cruising Speed Type	ERROR
`FplFormErr_speedv_invalid`	F15b	Invalid Cruising Speed Value	ERROR
`FplFormErr_flvlm_invalid`	F15c	Invalid Flight Level Type	ERROR
`FplFormErr_flvlv_invalid`	F15d	Invalid Flight Level Value	ERROR
`FplFormErr_routeTxt_*`	F15e	Various route errors	ERROR
`FplFormErr_ades_invalid`	F16a	Invalid Destination Aerodrome	ERROR
`FplFormErr_teet_invalid`	F16b	Invalid Total EET	ERROR
`FplFormErr_altad_invalid`	F16c	Invalid 1st Alternate Aerodrome	ERROR
`FplFormErr_alt2ad_invalid`	F16d	Invalid 2nd Alternate Aerodrome	ERROR
`FplFormErr_otherTxt_*`	F18	Various F18 indicator errors	ERROR
`FplFormErr_supl*`	F19	Various supplementary info errors	ERROR
`FplFormErr_addInfo*`	Add	Various additional info errors	ERROR
`FplFormWarn_adep_NoGisVal`	F13a	ADEP cannot be validated to GIS	WARN
`FplFormWarn_ades_NoGisVal`	F16a	ADES cannot be validated to GIS	WARN
`FplFormWarn_altAd_NoGisVal`	F16c/d	Alternate cannot be validated to GIS	WARN

✈️ FPL Validation Design Document

1. System Overview

2. Architecture

Key Components

Data Models

3. Validation Flow

4. Field-by-Field Validations

5. Cross-Field Checks

6. F18 Other Information Indicators

Indicator Parsing Rules

7. External Validation (AIS/GIS)

Aerodrome Validation (`AisGisAdValidation`)

Route Validation (`AisGisRouteValidation`)

8. Configuration

EOBT Time Format

9. Project Variants

10. Error Message Catalog

✈️ FPL Validation Design Document

1. System Overview

2. Architecture

Key Components

Data Models

3. Validation Flow

4. Field-by-Field Validations

5. Cross-Field Checks

6. F18 Other Information Indicators

Indicator Parsing Rules

7. External Validation (AIS/GIS)

Aerodrome Validation (AisGisAdValidation)

Route Validation (AisGisRouteValidation)

8. Configuration

EOBT Time Format

9. Project Variants

10. Error Message Catalog

Aerodrome Validation (`AisGisAdValidation`)

Route Validation (`AisGisRouteValidation`)