#! perl -slw
use strict;

my %in;
while( <DATA> ) {
     if( m[(\S+) (\d\d):\d\d (.+)$] ) {
        push @{ $in{ $1 }{ $2 } }, $3;
     }
     else {
        die 'Bad data';
     }
}


for my $airport ( sort keys %in ) {
    for my $hr ( sort{ $a <=> $b } keys %{ $in{ $airport } } ) {
        my $n = $#{ $in{ $airport }{ $hr } };
        my $step = 60 / $n;
        my $min = 0;
        for my $flight ( @{ $in{ $airport }{ $hr } } ) {
            printf( "%s %02d:%02d %s\n", $airport, $hr, int( $min ), $flight );
            $min += $step;
            $min = 59 if $min > 59;
        }
    }
}
__DATA__
...