Operation Crash-Dive is the 8th produced, and the 12th broadcast, episode of the British television series Thunderbirds.
The Fireflash airliner - pride of the Air Terranean passenger fleet - is making news again and, alas, for the wrong reasons: they're mysteriously disappearing! Speculation is rife, as to why: some internal failing of the aircraft itself? Or is it sabotage - again?
International Rescue offers its expertise to the authorities, to help solve the mystery - and finds its hands full, as Thunderbirds 1, 2 and 4 team up to locate one Fireflash that's crashed into the sea - and rescue its trapped crew from the sea-bottom...
To track down why the pilots misreported their positions - inadvertently misdirecting those trying to find them - Scott and Fireflash veteran Captain Hanson take another Fireflash out on a test flight. They're backed up by Virgil and Gordon, aboard Thunderbird 2, and Alan, coordinating communications between them and London International Airport from his orbital post aboard Thunderbird 5.
But when communications suddenly fail, and Fireflash's controls freeze up - sending the massive craft plummeting uncontrollably towards the sea - the odds change, for the worse!
- Team Fireflash: this episode reunites Scott and Captain Hanson, who was piloting a London-to-Tokyo AT flight discovered to have a bomb aboard, preventing it from landing - leading to the public debut of International Rescue (Trapped In The Sky).
Operation Crash-Dive on Thunderbirds Wiki: