IATA Airline Code Validation in Python — Lookup, ICAO & Callsign

1. What are IATA airline codes?

An IATA airline designator is a two-character code assigned by the International Air Transport Association to airlines operating scheduled and charter services. These codes are the backbone of commercial aviation — they appear on flight numbers, booking references, e-tickets, baggage tags, and interline agreements.

IATA designators consist of two alphanumeric characters. Most are two letters, but some include a digit — for example, 2K (Avianca Ecuador). The codes are unique to each operating airline and are essential for ticketing, baggage handling, and revenue accounting between carriers.

Some well-known examples: AA (American Airlines), BA (British Airways), LH (Lufthansa), LO (LOT Polish Airlines).

2. IATA vs ICAO airline codes

Two coding systems exist for airlines. IATA designators are two-character codes used in commercial aviation — ticketing, passenger-facing systems, GDS platforms, and baggage routing. ICAO designators are three-letter codes used in air traffic control, flight plans, and operational communications between ATC and pilots.

Passengers see IATA codes on boarding passes and flight displays (e.g. AA 100), while pilots and ATC use ICAO codes and callsigns on the radio (e.g. "American One Hundred" with ICAO prefix AAL). The two systems do not follow a predictable mapping — you need a lookup to convert between them.

3. The right solution: one API call

The IsValid IATA Airline API validates the format, looks up the airline in a comprehensive directory, and returns name, ICAO code, callsign, and country — 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 Airline Validation API docs →

4. Python code example

Using the isvalid SDK package or the requests library.

# airline_validator.py
import os
from isvalid import IsValid

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

# ── Validate a single airline ───────────────────────────────────────────────

result = iv.iata.airline("AA")
print(result["valid"])        # True
print(result["found"])        # True
print(result["name"])         # 'American Airlines'
print(result["icao"])         # 'AAL'
print(result["callsign"])     # 'AMERICAN'
print(result["countryCode"])  # 'US'

# ── List all airlines ───────────────────────────────────────────────────────

airlines = iv.iata.airline_list()
print(f"Total airlines: {len(airlines)}")

# airline_batch.py — validate multiple IATA airline codes
from typing import Any


def validate_airlines(code_list: list[str]) -> list[dict[str, Any]]:
    """Validate a list of IATA airline codes and return enriched results."""
    results = []

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

    return results


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

codes = ["AA", "BA", "LH", "XX", "00"]
results = validate_airlines(codes)

for r in results:
    if r.get("valid") and r.get("found"):
        status = "✓"
    elif r.get("valid"):
        status = "?"
    else:
        status = "✗"
    name = r.get("name", "not found")
    print(f"  {status}  {r['code']:<5}  {name}")

5. cURL example

American Airlines:

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

Valid format but not found in directory:

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

List all airlines:

curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://api.isvalid.dev/v0/iata/airline/list"

6. Understanding the response

Response for AA (American Airlines):

{
  "valid": true,
  "found": true,
  "iata": "AA",
  "name": "American Airlines",
  "icao": "AAL",
  "callsign": "AMERICAN",
  "countryCode": "US",
  "countryName": "United States"
}

Response for a valid format that is not in the directory:

{
  "valid": true,
  "found": false
}

Response for an invalid code:

{
  "valid": false
}

7. Edge cases to handle

# These are all valid IATA airline codes
codes = ["AA", "2K", "3K", "9W", "U2"]

for code in codes:
    result = iv.iata.airline(code)
    name = result["name"] if result["found"] else "not found"
    print(f"{code}: {name}")

# All of these return the same result
r1 = iv.iata.airline("aa")
r2 = iv.iata.airline("Aa")
r3 = iv.iata.airline("AA")

print(r1["iata"])  # → "AA"
print(r2["iata"])  # → "AA"
print(r3["iata"])  # → "AA"