def to_pilot_alpha(word):
    """Returns a list of pilot alpha codes corresponding to the input word

    >>> to_pilot_alpha('Smrz')
    ['Sierra', 'Mike', 'Romeo', 'Zulu']
    """

    pilot_alpha = ['Alfa', 'Bravo', 'Charlie', 'Delta', 'Echo', 'Foxtrot',
        'Golf', 'Hotel', 'India', 'Juliett', 'Kilo', 'Lima', 'Mike',
        'November', 'Oscar', 'Papa', 'Quebec', 'Romeo', 'Sierra', 'Tango',
        'Uniform', 'Victor', 'Whiskey', 'Xray', 'Yankee', 'Zulu']

    pilot_alpha_list = []
    
    word = word.upper()
    for c in word:
        index = ord(c) - 65
        pilot_alpha_list.append(pilot_alpha[index])

    return pilot_alpha_list