'Jump Complete' queried the current status of Thomas Cook's AOC. I can't answer that but I can offer some information as to how the CAA might manage this aspect of the demise of this air operator, for some 20+ years ago I was Head of the Flight Operations Inspectorate (Aeroplanes) and encountered a handful of similar situations. The process I describe below may not be followed exactly with TCX as there are several variables to be considered - but this is how it might proceed.
Because an AOC is valid on a Sunday (for example) it doesn't mean that it must be suspended on the Monday, for if an airline was considered by the CAA to have been safe to operate commercial air transport yesterday it is unlikely to have suddenly become unsafe overnight. Essentially, what needs to remain in place are the previously existing required post holders (and crews) and support from the approved maintenance organisation (MO). Therefore, provided the Authority receives assurances from the AOC holder that these remain in place, commercial air transport safety will probably not be considered at risk - for a time.
This means that the air operator may continue to fly his aircraft with his crews, maintained by the approved MO, with the aim of at least returning the aircraft to where he wants them to be and to carry passengers whilst doing so. The AOC is all about safety, and for as long as the CAA retains confidence that safety will not be compromised then the AOC can remain active. [This has nothing to do with the practicalities of flying away from home or maintenance base, for after landing at other airfields it is quite possible that the airport authorities may 'clamp' the aeroplane for as long as it takes them to be paid any dues outstanding, such as handling fees and air navigation service charges.]
What then happens, when all the aircraft are back where the administrators want them to be is that the Authority will in discussion with them learn what future the operator has (if any). Often, the administrator will express a desire not to forgo the AOC believing that it has some value: it doesn't! Within a few days of the collapse of the airline, and if there is little or no chance that it will be able to return to operations in the short term, the administrators will be invited to surrender the AOC voluntarily, asking that the Authority should place it in Suspension and learn from the latter what would be required for this to be lifted. This serves the interests of both parties: the administrators as it relieves them of certain charges, and the Authority because it saves them the paperwork exercise of giving 'Notice to Suspend' (or even 'Provisional Suspension' which is immediate but must still be accompanied by the aforementioned 'Notice'.) Once the AOC has been received by the Authority and the Suspension letter received by the administrators, the Authority can cease having to provide safety oversight. The final stage, 'Revocation', doesn't have to be done in a hurry but can follow following further discussions with the administrators when it is absolutely clear that the operator will not be able to ask that the Suspension be lifted.
Please believe me when I say that the Authority will endeavour to handle this whole process with sympathy and understanding. Before joining the UK CAA in 1982 I was a BAC 1-11 Captain with Laker Airways and so understand completely many of the emotions that must be assailing all those who find that their employer has suddenly ceased training. To those who were employed as aircrew with Thomas Cook I can only say that, bleak though the picture might seem right now, your experience as flight or cabin crew should stand you in good stead for new employment with another operator, quite possibly sooner than you might think. If your experience mirrors mine, you will find those in the industry to whom you come into contact sympathetic to the situation you are in and willing to help you if they possibly can. Take heart!