[singpilot]

Yep, that is the stink of it. Why would a competant crew take a plane with some sort of pressurization problem up to altitude. This is the typical foreign supplemental carrier. Experienced captain (usually from USA, or Common Market Country) from Germany, low time FO from flag of airline, Cypress in this case.

There are a couple of 'innocent' explanations as well. Technical, but relatively innocent. To enhance takeoff performance, there is a procedure to allow the APU to provide cabin pressurisation as well as heating and cooling in flight at low altitudes. So you take off using the APU to unload the engines, allowing them to have all available thrust for performance when needed. This was a short flight, long takeoff runway in Larnaca, sea level airport, not much fuel required (refuel planned in Athens for the continuing flight to Prague). I would have said it wasn't required that day, but then who knows what the captain wanted.

Normally, the transition back to engines for pressurisation would be after cleanup, say 6 to 7 thousand feet. Takes throttles to low power for a sec, three buttons pressed, then shut down the APU and continue. Maybe a minute, two if your new at it, or reading the checklist while doing it.

Lets speculate again for a sec (dangerous). If you forgot to do this, the climbing APU will have to work progressively harder and harder to accomplish the requested tasks. It is rated for 15000 feet under this kind of load. If they forgot or realized late, or had a weak APU, all of this would have come to head about that altitude. Perhaps explains the requested pause in the climb. Would also explain why they requested the continued climb in spite of the obvious result (after transitioning back to engines for pressurisation). The FDR (Flight Data Recorder) will shed light on this.

Interesting note here. Regs require enough fuel to destination, alternate and 45 more minutes. Alternate was probably back to Larnaca (45 minutes), plus 45 minutes actual reserve. Hold at Athens was 90 minutes, then flameout.


Will be interesting to see how it turns out.