The TARDIS materialises at modern-day Heathrow Airport, where a Concorde airplane has just vanished from the skies. The Doctor, Nyssa and Tegan offer to help, and they board a second Concorde which follows the same flight path as the first. They discover a time corridor which propels them back to the Pleistocene Era. There they find that the first Concorde's crew and passengers have been enslaved by the sinister sorcerer Kalid, who is forcing them to excavate a sanctum within a mysterious citadel. An alien intelligence takes possession of Nyssa, warning the Doctor of the great peril that awaits him within.

Peter Grimwade's first experience with Doctor Who came in 1970, as a production assistant on Spearhead From Space. He returned in this capacity intermittently over the next decade, during which he also began developing story ideas for the show. One proposal concerned an evil force which took control of a rogue element amongst an alien species; it was submitted to script editor Douglas Adams in 1979, but was rejected. In 1980, Grimwade resubmitted the concept to Adams' successor, Christopher H Bidmead, who felt that the notion was worth pursuing.

Bidmead and Grimwade were soon engaged in further discussions. An errand at London's Heathrow Airport during one of their meetings inspired the involvement of Concorde -- the world's first commercial supersonic aircraft, which had only been in service for four years. In addition to being a timely and impressive element of the narrative, Bidmead thought that it would help ground the fantastical plot in reality. Soon thereafter, on March 14th, Grimwade was commissioned to produce a storyline under the title “Zanadin” -- a name which had been conceived by Grimwade, Bidmead and producer John Nathan-Turner to be intentionally bizarre. The production team liked this style of title, which they felt was more intriguing for viewers than the standard Doctor Who approach.

Consideration was given to positioning “Xeraphin” as the final adventure of Season 18

Grimwade worked quickly on his outline, and consideration was given to positioning the story -- now renamed “Xeraphin” -- as the final adventure of Doctor Who's eighteenth season. At about this time, however, Nathan-Turner hired Grimwade to direct another Doctor Who serial, Full Circle, which meant delaying work on “Xeraphin”. It was subsequently agreed that Grimwade would revisit his adventure at the end of the summer -- after completing Full Circle and before directing the eventual Season Eighteen finale, Logopolis -- with a view to making “Xeraphin” as part of Doctor Who's nineteenth season.

The postponement of “Xeraphin” was beneficial in at least one respect, as it gave Nathan-Turner more time to negotiate access to Heathrow Airport and a British Airways Concorde for filming -- both firsts for a television drama. Aided by specious insinuations that the Doctor Who production office was in discussions with Air France for similar accommodations, Nathan-Turner scored a major coup when he was able to obtain the necessary permissions. This development would later come as a surprise to David Reid, the new Head of Series and Serials, after he warned Nathan-Turner about the unfeasibility of a Doctor Who story based around Concorde.

As 1980 wore on, it became clear that Grimwade would have to make several changes to his storyline. Tom Baker had now decided to leave Doctor Who, and so “Xeraphin” would feature a very different TARDIS crew. In addition, Nathan-Turner and Bidmead had reintroduced the Doctor's Time Lord arch-nemesis, the Master, and the producer was eager to feature the character in two stories every year. It was planned that the Master would appear in Season Nineteen's debut serial (eventually Castrovalva), and Nathan-Turner asked Grimwade to incorporate the character into “Xeraphin” as well. With the storyline duly amended, Grimwade was formally commissioned to script his adventure on September 22nd. The contract was issued under the title “Zanadin”, but the story reverted back to “Xeraphin” soon thereafter.

More alterations became necessary over the course of 1981. It had been decided that Adric would be dropped as a companion in the story preceding “Xeraphin”, and so he would have to be removed from the action. Furthermore, since “Xeraphin” was now intended to be the last serial of Season Nineteen, Nathan-Turner wanted to end the year on a moment of suspense, akin to the Doctor's regeneration in Logopolis. It was agreed that “Xeraphin” should culminate in Tegan's apparent abandonment as the Doctor and Nyssa departed in the TARDIS. There were no plans to write Janet Fielding out of Doctor Who, but this development would also give Nathan-Turner the flexibility to change his mind about retaining Tegan, if necessary. Meanwhile, new script editor Eric Saward felt that the Master had worn out his welcome. He championed the idea of killing off the villain in “Xeraphin”, but Nathan-Turner was adamant that he wanted the Master to be a recurring foe for the foreseeable future.

At one point, Peter Grimwade hoped to direct his own scripts

At one point, Grimwade hoped to direct his own scripts, but this was made impossible when he was assigned to Earthshock, the previous serial in production. Over the summer, Andrew Morgan was instead recruited for “Xeraphin”. However, he was unimpressed by Grimwade's scripts, and was then offered another opportunity he found more enticing. As a result, Morgan turned down the Doctor Who job at the last minute; he would eventually make his debut on the show with Time And The Rani in 1987. Now left with little time to find a replacement, Nathan-Turner turned to Ron Jones, a neophyte director who was just completing Black Orchid. Jones agreed to move straight onto “Xeraphin”.

Anthony Ainley was contracted to play the Master on October 1st. It was agreed that he would be credited as “Leon Ny Taiy” (an anagram of “Tony Ainley”) at the end of Episode One, in order to preserve the surprise of Kalid's unmasking in the second installment. It was also observed that Adric's death at the climax of Earthshock might be spoiled if advance cast listings for the season finale omitted Matthew Waterhouse's name. Consequently, a brief appearance by an illusory Adric was added to Episode Two. Meanwhile, both of Grimwade's Concorde captains had to be renamed to avoid confusion with real individuals: Irving became Markham and then Urquhart, while Rathbone became Stapley. Flight Engineer Tulley was subsequently rechristened Scobie. In mid-December, the story was renamed Time-Flight. Other options such as “Flight Into Time” had also been considered, and there was some discussion as to whether or not Time-Flight should be hyphenated.

It was originally hoped that filming for Time-Flight at Heathrow Airport would take place before Christmas. In the event, however, work there began on January 6th, 1982; as a result, more than a month had elapsed since the end of recording on Earthshock. The first day at Heathrow was spent on the concourse in Terminal One. On the 7th, the production shifted to the roof of the Terminal Three car park. Work on this day included Tegan's apparent departure, although Fielding had been reassured as far back as September that Tegan was returning for Season Twenty. The Heathrow shoot was intended to conclude on January 8th, but the Concorde which British Airways had planned to provide had to be pressed into service that day. As a result, scenes inside the aircraft and on the tarmac were postponed to the 11th, when they were recorded at the British Airways Maintenance Area. Unfortunately, a scratch was subsequently discovered on some of the Concorde footage. Since there was no way to re-record the material, judicious edits were required.

In addition to the work at Heathrow, Jones had hoped that some of the scenes on the prehistoric heath might also be filmed on location or, alternatively, at the BBC Television Film Studios in Ealing, London. He was disappointed to learn that the budget for Time-Flight would not permit this. In the event, the heath was the focus of the serial's first studio block, on January 19th and 20th at BBC Television Centre Studio 8 in White City, London. Originally, this work was intended to be confined to the first day, but technical problems pushed some scenes back. This resulted in a race against time to complete the other planned shots -- in and around the Heathrow offices, as well as various special effects -- on what remained of the second day. Nathan-Turner was dissatisfied with the results, and some of the material was remounted in TC8 on January 24th.

By this stage, there was considerable unhappiness regarding the Plasmaton costumes, which had been constructed by the freelance firm Imagineering of Witney, Oxfordshire. The intent had been to create something inhuman, but insufficient thought had been given to the eyesight of those wearing the outfits. Unable to see, the Plasmaton performers had to remain virtually immobile, and were scarcely able to generate a sense of menace. Meanwhile, it had been discovered that the script for Episode Three was drastically short; on January 25th, Saward asked Grimwade to develop a further seven minutes of action. Later that week, Grimwade provided various new and extended scenes, including more material involving Bilton and Stapley spying on the Master and later trying to pilot the TARDIS, and additional exposition about the Xeraphin.

The second studio block -- again in TC8 -- spanned February 1st to 3rd. The initial day concentrated on TARDIS material. The middle day was devoted to scenes in the Concorde hold, the area outside the sanctum, and the various corridors of the citadel. Waterhouse returned to finish out his tenure on Doctor Who, more than two months after recording his farewell adventure. February 3rd was the final day of production for both Time-Flight and Season Nineteen as a whole. The material that remained to be taped included the sequences in Kalid's chamber and the Xeraphin sanctum, plus some further modelwork.

The transmission of Time-Flight Episode Four brought Doctor Who's nineteenth season to a close on March 30th. It aired fifteen minutes earlier than usual, at 6.50pm, because the animated short which usually preceded Doctor Who had been dropped from the schedule. The next programme to occupy the Monday and Tuesday timeslots on a regular basis was another twice-weekly series: the soap opera Triangle, which was entering its second season.

• Doctor Who Magazine #294, 23rd August 2000, “Archive: Time-Flight” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who Magazine Special Edition #1, 2001, “Prince Charming” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Complete History #35, 2018, “Story 122: Time-Flight”, edited by John Ainsworth, Hachette Partworks Ltd.
• Doctor Who: The Eighties by David J Howe, Mark Stammers and Stephen James Walker (1996), Virgin Publishing.
• Doctor Who: The Handbook: The Fifth Doctor by David J Howe and Stephen James Walker (1995), Virgin Publishing.
• In·Vision #61, November 1995, “Production” edited by Anthony Brown, Cybermark Services.