Now in my time (67-70) Tengah was a Mon-Fri operation, usually with Night Flying Mon-Thu. Thus weekends were leisure time... usually. Changi was the Master Airfield, open 24/7. However, it was not unusual for our OC Fg Wg (Wg Cdr M W P K) to open the airfield for the occasional weekend movement, such as a freight run. Why, you might ask, did that aircraft not go to Changi which was open anyway? Great careers are not built on saying "No", I suspect, and thus the assembly of ATC, Fire Section and a whole bunch of others would be required. These were almost exclusively shift workers, and thus would have to be 'invited' to attend their normal workplace on, say, Sunday morning. This obviously entailed a degree of phoning around to give out the good news. Now phone calls from work at the weekend only meant one thing ... and thus disguised voices would be used by the recipient to confound the caller, hopefully leading to a disconnected line. I never answered the phone in person at weekends, as a precaution!