flightxml SEARCH occasionally returns Internal Server Error

FlightAware AeroAPI
1

My server does a SEARCH once every five minutes. Usually it works. But occasionally my PHP SOAPclient returns an Internal Server Error. That is an error returned by flightaware’s servers, I presume. Just wondered if it can be fixed.
Example:-


[28-Sep-2015 00:00:40 UTC] fagrab: no SearchResult: SoapFault::__set_state(array(
   'message' => 'Internal Server Error',
   'string' => '',
   'code' => 0,
   'file' => '<my program>',
   'line' => 39,
   'trace' => 
  array (
    0 => 
    array (
      'function' => '__doRequest',
      'class' => 'SoapClient',
      'type' => '->',
      'args' => 
      array (
        0 => '<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns1="http://flightxml.flightaware.com/soap/FlightXML2"><SOAP-ENV:Body><ns1:SearchRequest><ns1:query>-latlong "50.53 -2.15 51.15 -1.0"</ns1:query><ns1:howMany>15</ns1:howMany><ns1:offset>0</ns1:offset></ns1:SearchRequest></SOAP-ENV:Body></SOAP-ENV:Envelope>
',
        1 => 'http://flightxml.flightaware.com/soap/FlightXML2/op',
        2 => 'FlightXML2:Search',
        3 => 1,
        4 => 0,
      ),
    ),
    1 => 
    array (
      'file' => '<my program>',
      'line' => 39,
      'function' => '__call',
      'class' => 'SoapClient',
      'type' => '->',
      'args' => 
      array (
        0 => 'Search',
        1 => 
        array (
          0 => 
          array (
            'query' => '-latlong "50.53 -2.15 51.15 -1.0"',
            '-inAir' => 1,
            'howMany' => 15,
            'offset' => 0,
          ),
        ),
      ),
    ),
    2 => 
    array (
      'file' => '<my program>',
      'line' => 39,
      'function' => 'Search',
      'class' => 'SoapClient',
      'type' => '->',
      'args' => 
      array (
        0 => 
        array (
          'query' => '-latlong "50.53 -2.15 51.15 -1.0"',
          '-inAir' => 1,
          'howMany' => 15,
          'offset' => 0,
        ),
      ),
    ),
  ),
   'previous' => NULL,
   'faultstring' => 'Internal Server Error',
   'faultcode' => 'HTTP',
))