The One Where the Fireflash comes back for seconds.
A Fireflash aircraft crashes into the ocean, with the loss of all hands (not least because the position given by the flight crew is considerably inaccurate): the entire fleet is grounded, but repeated tests fail to identify the cause of the accident. Determined to track the problem, a test flight is made and an identical problem occurs. This time, International Rescue are on the scene and cut the massive engines away from the craft, allowing it to rise to the surface.
Continued, thorough tests fail to locate the problem and International Rescue are called to assist on a second test flight. With ace, veteran Fireflash pilot, Captain Hansen (from "Trapped In The Sky") as pilot and the highly-trained Scott Tracy as co-pilot (and with Thunderbird 2 flying alongside), the flight begins as normal. The same critical failures then occur, however this time Gordon Tracy is able to enter Fireflash's wing compartment and attempt repairs. There, he discovers the terrifying truth about the Fireflash crashes...
- A Day in the Limelight: Thunderbird 5 has a much bigger role in this episode than usual, since it is used to keep track of the Fireflash test flights.
- A Million Is a Statistic: This episode has a pretty high body count when you consider the first Fireflash (with hundreds of unseen people on board) goes down without IR around to help. IR does go out of its way to save the two pilots aboard the second one.
- Chekhov's Boomerang: A very big full circle example. After saving the original Fireflash along with all passengers and crew in "Trapped In The Sky", sadly in this episode, International Rescue were not around to save any of the 600 lives from the first Fireflash. However they saved the solitary 2 crew members from the second Fireflash, before its destruction, then saved the third Fireflash and solitary crew as well and finally solving the mystery of the recurring Fireflash disasters at the same time.
- Combat Pragmatist: Gordon tricks the saboteur into trying to parachute out of the Fireflash, then shoots him in the back.
- Continuity Nod: The episode constantly references the series premiere, Trapped in the Sky. Several characters from that episode return.
- Fridge Horror: We never actually see how the 600 passengers and crew on board the first Fireflash die and what became of that aircraft, however the ultimate fate of the second Fireflash strongly suggests they were either all burned to death or blown to pieces along with the aircraft after its damaged electrics and fuel systems caught fire.
- Take a Third Option: In the climax, the third Fireflash (with Scott and Gordon on board) is about to crash into the ocean and Gordon realizes there is no time to properly fix the cut cable of the Elevator Power Unit. His solution? Simply hold the two ends together with his bare hands. It works.
- Up to Eleven: Thunderbird 2, the largest Thunderbird (that doesn't travel to or reside in Space), is utterly dwarfed next to the Fireflash.
- The Unfavorite: This episode makes it pretty clear Gerry Anderson didn't like John: Thunderbird 5 for once gets to do something other than relay the mission of the week and this Day in the Limelight for the space station coincides with Alan being on duty relieving John.
- Vehicular Sabotage: What happens to several Fireflash crafts.
- What the Hell, Hero?: Not only does International Rescue not launch to save the first Fireflash, they don't even bother to radio the search and rescue teams to let them know they're looking in the wrong place.