<?php

  $locations = array ( 
    'phone' => array ( 
      0 => '555-123-1234', 
      1 => '555-456-4321',
      2 => '555-789-1122',
      3 => '555-321-1111'
    ),
    'address' => array ( 
      0 => '123 Main Street BigCity, NY 12345',
      1 => '456 Maple Street Somewhere, UT 87654',
      2 => '999 1st Ave MyTown, VA 23456',
      3 => '321 2nd Ave MyTown, VA 23456'
    ),
    'distance' => array ( 
      0 => 24.56,
      1 => 13.05,
      2 => 23.99,
      3 => 1.75
    ), 
    'name' => array ( 
      0 => 'First Location',
      1 => 'Second Location',
      2 => 'Third Location',
      3 => 'Fourth Location'
    ) 
  );

  $locationsAsRows = array();
  for ($i = 0; isset($locations['phone'][$i]); $i++) {
    $locationsAsRows[$i] = array (
      'phone' => $locations['phone'][$i],
      'address' => $locations['address'][$i],
      'distance' => $locations['distance'][$i],
      'name' => $locations['name'][$i]
    );
  }

  echo "Before sorting:\n";
  print_r($locationsAsRows);

  array_multisort($locations['distance'], SORT_NUMERIC, $locationsAsRows);

  echo "\n\nAfter sorting:\n";
  print_r($locationsAsRows);

Before sorting:
Array
(
    [0] => Array
        (
            [phone] => 555-123-1234
            [address] => 123 Main Street BigCity, NY 12345
            [distance] => 24.56
            [name] => First Location
        )

    [1] => Array
        (
            [phone] => 555-456-4321
            [address] => 456 Maple Street Somewhere, UT 87654
            [distance] => 13.05
            [name] => Second Location
        )

    [2] => Array
        (
            [phone] => 555-789-1122
            [address] => 999 1st Ave MyTown, VA 23456
            [distance] => 23.99
            [name] => Third Location
        )

    [3] => Array
        (
            [phone] => 555-321-1111
            [address] => 321 2nd Ave MyTown, VA 23456
            [distance] => 1.75
            [name] => Fourth Location
        )

)


After sorting:
Array
(
    [0] => Array
        (
            [phone] => 555-321-1111
            [address] => 321 2nd Ave MyTown, VA 23456
            [distance] => 1.75
            [name] => Fourth Location
        )

    [1] => Array
        (
            [phone] => 555-456-4321
            [address] => 456 Maple Street Somewhere, UT 87654
            [distance] => 13.05
            [name] => Second Location
        )

    [2] => Array
        (
            [phone] => 555-789-1122
            [address] => 999 1st Ave MyTown, VA 23456
            [distance] => 23.99
            [name] => Third Location
        )

    [3] => Array
        (
            [phone] => 555-123-1234
            [address] => 123 Main Street BigCity, NY 12345
            [distance] => 24.56
            [name] => First Location
        )

)