IATA Flight Number Validation in Python — Airline Lookup & Parsing

1. What is an IATA flight number?

An IATA flight number (also called a flight designator) is a code assigned to a scheduled airline service. It consists of a 2-character airline code followed by a 1- to 4-digit number and an optional single-letter suffix. These identifiers appear on boarding passes, airport departure boards, flight-tracking apps, and GDS booking systems.

Some well-known examples: AA100 (American Airlines), LH438 (Lufthansa), BA15 (British Airways), EK1 (Emirates).

2. Structure breakdown

An IATA flight number has three parts. Understanding this structure helps when parsing user input, validating API payloads, or building flight search interfaces.

Combined, a flight number like LH438B breaks down as: airline code LH (Lufthansa), flight number 438, suffix B.

3. Why flight number validation matters

4. The right solution: one API call

The IsValid IATA Flight API validates the flight number format, parses it into its component parts, and enriches it with airline metadata — airline name, country, ICAO callsign, and more — all from a single GET request.

Get your free API key at isvalid.dev — 100 calls per day, no credit card required.

Full parameter reference and response schema: IATA Flight Validation API docs →

5. Python code example

Using the isvalid SDK package or the requests library.

# flight_validator.py
import os
from isvalid import IsValid

iv = IsValid(api_key=os.environ["ISVALID_API_KEY"])

# ── Example usage ────────────────────────────────────────────────────────────

result = iv.iata.flight("AA100")

print(result["valid"])        # True
print(result["airlineCode"])  # 'AA'
print(result["flightNumber"]) # 100
print(result["airlineName"])  # 'American Airlines'
print(result["suffix"])       # None

if result["valid"]:
    print(f"Flight {result['airlineCode']}{result['flightNumber']} — {result['airlineName']}")
    # → Flight AA100 — American Airlines

# flight_batch.py — validate multiple flight numbers
from typing import Any


def validate_flights(flight_list: list[str]) -> list[dict[str, Any]]:
    """Validate a list of IATA flight numbers and return enriched results."""
    results = []

    for flight in flight_list:
        try:
            data = validate_flight(flight)
            results.append({"flight": flight, **data})
        except Exception as exc:
            results.append({"flight": flight, "valid": False, "error": str(exc)})

    return results


# ── Example ──────────────────────────────────────────────────────────────────

flights = ["AA100", "LH438B", "BA15", "INVALID", "123"]
results = validate_flights(flights)

for r in results:
    status = "✓" if r.get("valid") else "✗"
    airline = r.get("airlineName", "unknown")
    print(f"  {status}  {r['flight']:<10}  {airline}")

6. cURL example

American Airlines flight 100:

curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://api.isvalid.dev/v0/iata/flight?value=AA100"

Lufthansa flight with suffix:

curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://api.isvalid.dev/v0/iata/flight?value=LH438B"

Invalid format:

curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://api.isvalid.dev/v0/iata/flight?value=INVALID"

7. Understanding the response

Response for AA100 (American Airlines):

{
  "valid": true,
  "airlineCode": "AA",
  "flightNumber": 100,
  "suffix": null,
  "airlineName": "American Airlines",
  "countryCode": "US",
  "countryName": "United States",
  "callsign": "AMERICAN",
  "icao": "AAL"
}

Response for an invalid flight number:

{
  "valid": false
}

8. Edge cases to handle

# Both codeshare partners have valid flight numbers
marketing = iv.iata.flight("BA1525")
operating = iv.iata.flight("AA100")

print(marketing["valid"])       # True
print(marketing["airlineName"]) # 'British Airways'
print(operating["airlineName"]) # 'American Airlines'

result = iv.iata.flight("LH438B")

print(result["airlineCode"])  # 'LH'
print(result["flightNumber"]) # 438
print(result["suffix"])       # 'B'
print(result["airlineName"])  # 'Lufthansa'

r1 = iv.iata.flight("AA0100")
r2 = iv.iata.flight("AA100")

print(r1["flightNumber"])  # 100
print(r2["flightNumber"])  # 100

r1 = iv.iata.flight("aa100")
r2 = iv.iata.flight("AA100")

print(r1["airlineCode"])  # 'AA'
print(r2["airlineCode"])  # 'AA'