SAA 737 pressurisation oops...
I'm hoping there is someone out there who can settle my curiosity...
I flew from Nairobi to Jo'burg on Monday this week on an SAA 737-800. The aircraft was only 1/3 full, and everything was absolutely normal until we were top of climb. Then I got a few 'ear pops' which was the first clue something odd was up. Then there was a substantial power reduction, power back up, power reduction and the aircraft was fairly steeply descended. I'm not a big jet pilot but from experience flying a corporate jet it all seemed rather odd. Eventually we leveled out somewhat lower than original, but there was a serious out of sync vibration in the cabin. This vibration continued on and off for the next hour at least, with various power changes as the crew tried to sort something out. The engines stabilised for 15 minutes at a time, then went out of sync again etc. After sometime the flight deck explained that they had had a problem with pressurisation at 38,000' so had come back down to 28,000' and were continuing onto Jo'burg as scheduled. The rest of the flight was normal, except we seemed to have several large changes of heading which I don't recall from past flights on the same route.
Lastly, there was a few minutes when the cockpit door was ajar and we could see a bank of annunciators in the centre panel that seemed to have at least 3 amber and 1 red lights showing on the top row?. Again I know nothing about the 737 but small jets normally operate with a black/clear annunciator panel.
As a postscript to the above, by coincidence a friend was travelling the reverse route the very next day on SAA, and shortly out of Jo'burg the crew on the 737-800 announced they had a pressurisation problem and turned back to Jo'burg at FL080' all the way back in. He waited a while and got put on another aircraft to Nairobi a few hours later.
So, can anyone out there shed any light on what was happening, what went wrong or why?? I'm just curious more than anything else. I'm also guessing that there are very different SOP's for pressurisation issues when heading inbound to home-base than when outbound. But I can't help wonder if it was the same aircraft and the problem hadn't been rectified satisfactorily after the inbound flight....